2014 Ipvm Ip Camera Fundamentals

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Table Of Contents

CAMERA & VIDEO FUNDAMENTALS............................................................................................... 4

Resolution Tutorial.......................................................................5

Pixels Determine Potential, Not Quality ............................................ 12

Average Frame Rate Used for Recording ............................................ 17

Shutter Speed / Exposure Tutorial ................................................... 22

Testing: Gain / AGC Impact on Surveillance Video................................. 25

WDR Tutorial............................................................................ 37

LENSES........................................................................................................................................... 46

Lens Focal Length Tutorial ............................................................ 47

Field of View (FoV) Tutorial .......................................................... 51

Varifocal vs. Fixed Lens ............................................................... 57

Focusing Tutorial ....................................................................... 61

F-Stop Tutorial ......................................................................... 66

Shutter Speed / Exposure Tutorial ................................................... 70

Lens Iris Tutorial ....................................................................... 73

Depth of Field Tutorial ................................................................ 77

Lens Selection Recommendations .................................................... 82

CAMERA SELECTION...................................................................................................................... 87

IP Camera Form Factor Selection .................................................... 88

Minidomes vs. Full Size Domes....................................................... 102

IP Camera Specification Guide ...................................................... 106


CAMERA & VIDEO FUNDAMENTALS


Resolution Tutorial

Understanding video surveillance resolution is surprisingly difficultand complex. While the word 'resolution' seems self-explanatory,its use in surveillance is far from it. In this tutorial, we will explain 5critical elements:

What resolution traditionally means – seeing details - and theconstraints of this approach

What resolution usually means in surveillance – pixels – andthe limits of using this metric

How sensor and stream resolutions may vary How compression impacts resolution greatly What limits resolution's value

Resolution – Seeing DetailsIn normal English and general usage, resolution means the ability toresolve details – to see or make them out. For example, can youread the lowest line on an eye chart? Can the camera clearlydisplay multiple lines side by side on a monitor? Etc. It is aperformance metric focusing on results.

Historically, video surveillance used this approach. Analog cameraresolution was measured with line counts, literally the camera'sability to display more lines side by side in a given area on amonitor.


If you could see more lines, it meant you could see more real worlddetails – facial features, characters, license plates, etc.

The main limitation was that resolving power – lines counted – wasalways done in perfectly even lighting conditions. However, withdirect sunlight or low light, the resolving power would change,likely falling significantly. Even more challenging, some camerasfared far worse in these challenging lighting conditions than others.

While this approaches measures performance, it only does so inthe most ideal, and often unrepresentative, conditions.

Resolution – Pixel CountNow, with the shift to IP, manufacturers do not even attempt tomeasure performance. Instead, resolution has been redefined ascounting the number of physical pixels that an image sensor has.


Pixels Determine Potential, Not QualityPixels are a necessary, but not sufficient, factor for capturingdetails. Without a minimum number of pixels for a given area /target, it is impossible. See our tutorial on why Pixels DeterminePotential, Not Quality.

LimitationsThe presumption is that more pixels, much like higher line counts,delivers higher ‘quality’. However, this is far from certain.

Just like with classic resolution measurements that used only ideallighting conditions, measuring pixels alone ignores the impact ofcommon real world surveillance lighting challenges. Often, but notalways, having many more pixels can result in poorer resolvingpower in low light conditions. Plus, cameras with lower pixel countsbut superior image processing can deliver higher quality images inbright sunlight / WDR scenes.

http://ipvm.com/updates/2294



Nonetheless, pixels have become a cornerstone of specifying IPvideo surveillance. Despite its limitations, you should:

Recognize that when a surveillance professional is talkingabout resolution, they are almost certainly referring to pixelcount, not resolving power

Understand the different resolution options available

The table below summarizes the most common resolutions used inproduction video surveillance deployments today:

Everything else equal, you should expect to pay more for higherresolution (i.e. pixel count) cameras. While these cameras canoften deliver more details, keep in mind performance variances(low light, WDR).

Resolution – Sensor vs. StreamWhile manufacturers typically specify cameras based on theresolution (i.e. pixel count) of the sensor, sometimes, theresolution of the stream sent can be less. This happens in 2 cases:


The manufacturer uses a higher resolution sensor thanmaximum stream they support. One common example of thisis panoramic cameras where a 5MP sensor may be used butonly a 2MP max output stream is available.

The integrator explicitly or mistakenly sets a camera to alower resolution. Some times this is done to save bandwidthbut other times it is simply an error or glitch in the VMSdefault resolution configuration. Either way, many times anHD resolution may look ‘terrible’ but the issue is simply that itis not set to its max stream resolution (i.e., a 3MP camera setto 640 x 480).

Make sure to check not only the resolution of the sensor but thestream resolutions supported and used.

Don’t Forget CompressionSince resolution now measures physical pixels, it does not considerhow much the pixels are compressed. Each pixel is assigned a valueto represent its color, typically out of a range of ~16 million (24bits), creating a huge amount of data. For instance, a 1080p/30fpsuncompressed stream is over 1Gb/s. However, with digital videotoday, surveillance video is almost always compressed. That1080p/30fps stream would more typically be recorded at 1Mb/s to8Mb/s – 1/100th to 1/1000th less than the uncompressed stream.The only question – and it is a huge one – is how much does videoget compressed?

The positive side is the potential to massively reducebandwidth/storage without significantly impacting visible imagequality. That is why it is nearly universally done.


However, picking the right compression level can be tricky. Howmuch compression loss can be tolerated often depends onsubjective preferences of viewers or the details of the scene beingcaptured. Equally important, increasing compression can result ingreat cost saving on hard drive, switch and server reductions.

Just because two cameras have the same resolution (i.e. pixelcounts), the visible image quality could vary substantially becauseof differences in compression levels chosen. Read our video quality/ compression tutorial to dig into these details.

Limitations on Resolution ValueEven if quality increased exactly in proportion to pixel count (whichit obviously does not), two other important limits exist in practicalusage: angle of incident and resolution needed.

Angle of IncidentRegardless of how high quality an image is, it needs to be at aproper angle to 'see' details of a subject, as cameras cannot seethrough walls nor people. For instance:

Even if the image on the left had 10x the pixels as the one on theright, the left one is incapable of seeing the full facial details of the

http://ipvm.com/report/video_quality



subject. This is frequently a practical problem in trying to cover afull parking lot with a single super high resolution camera. Even ifyou can get the 'right' number of pixels, if a car is driving oppositeor perpendicular to the camera, you may not have any chance ofgetting its license plate (similarly for a person's face).

Resolution Needed / OverkillTypically and historically, surveillance has been starved forresolution, with almost always too little for its needs. However, asthe amount of pixels increases to 2MP and beyond, frequently thiscan be overkill. Once you have enough to capture facial and licenseplates details, most users get little practical benefit from morepixels. The image might look 'nicer' but the evidentiary qualityremains the same. This is a major consideration when looking atPPF calculations and ensuring that you do not 'waste' pixels.

Factors Impacting ResolutionUnfortunately, many factors impact surveillance resolution, farbeyond pixels, such as:

Low light performance WDR performance Compression settings Camera angle / downtilt Lens selection and focus

Do not accept specified resolution (i.e. pixel count) as the one andonly quality metric as it will result in great problems. Understandand factor in all of these drivers to obtain the highest quality foryour applications.

http://ipvm.com/report/definitive_guide_ppf




http://ipvm.com/report/testing_camera_height




Pixels Determine Potential, NotQuality

The most damaging misconception in surveillance is that pixels = resolution =

quality. In fact, pixels determine potential quality, limited by many other

important factors. In this note, we explain why you will make much clearer and

better decisions recognizing this.

Demonstrating This With Images

Here's a relatively high quality, high 'resolution' image:

It's 161 pixels wide across a small area of 1 - 2 feet, delivering a high ~100 PPF.

Now contrast this with this low quality, low resolution image:



This is 5 pixels wide and a total of 35 pixels covering the same exact area as the

image above (enlarged so you can see it). This is clearly low quality.

Why? The pixels are being forced to cover areas wider than the details desired.

You can see it the blockiness of the image. Those blocks are the limits of the pixel.

The image calls out 3 of the 35 pixels but you can make out pretty much all the

individual pixels.

Now let's increase the pixels / resolution for this image.


A lot more details are being revealed now, as the number of pixels increases from

35 total to 140 and each pixel now can cover a smaller area.

Let's compare the two images to see key details in the image improve:

In the former image, the eyes were bigger than the pixels and therefore could not

be captured. However, in the latter one, with pixels cover an area smaller than an

individual eye, allows the eyes to be captured as two black dots.

Let's increase the pixels for this scene, from 140 to 240:


As each pixel covers a smaller area, more features continue to emerge - lips, ears,

etc. and the eyes become more detailed (eyebrows, iris, etc.).

Finally, here's 4 samples ranging from 35 to 2120 pixels covering the same area:

Clearly, as we increased pixels allocated, the more fine details that can be

captured.

The smaller pixel count images, regardless of how 'good' the camera or encoder

was could not capture those details because the pixels were covering too large an

area for them. This is what we mean by pixels determine potential.

Pixels Limits on Quality


A 1MP camera will never capture the fine details of the face of a subject at a 50'

wideFoV. It simply lacks the potential, because the pixels will cover too large an

area relative (25ppf) to how small a face is at the same position.

However, a 5MP came covering that same 50' wide FoV may capture the fine

details. It has the potential, because the pixels will be covering small enough

areas (50ppf).

This potential, though, is a maximum theoretical limit bound by very important

factors like:

Ability to capture in low light scenes (which most 5MP+ cameras are

terrible at).

Ability to handle wide dynamic range scenes (see example).

Quality of lens, preciseness of focus and eliminating any DoF problems.

Minimizing compression artifacts / loss of quality (see tutorial).

Angle of incident of subject to camera (if the camera is too high or the

person is looking askew from the camera, more pixels will not help).

Quality vs Pixels

Ultimately, image quality is driven by a half dozen factors combined. While pixel

density / count determines the potential quality and the maximum achievable

details, those other factors, that are often overlooked and ignored in PPF

calculations, routinely and often dramatically constrain the actual image quality

achieved.





http://ipvm.com/report/testing_camera_height




Average Frame Rate Used forRecording

People are used to watching TV at about 30 frames per second,often called 'full' frame rate. In the video surveillance world, fullframe rate IP cameras are becoming more and more common.Indeed, today, most professional IP cameras are designed tostream up to 30 frames per second.

However, what frame rate is actually being used in the field today?In this note, we share the responses from over 80 integrators whodeploy 1000s of systems around the world. This shows what reallyis chosen and why it is.

Let's start with a table that breaks down integrator responses:


http://ipvm-uploads.s3.amazonaws.com/uploads/e374/b5ed/avg-frame-rate-recording.jpg


What stands out right away is how low the average frame rate usedfor video surveillance recording is. Nearly 70% record at 10fps orless, a level that is about 70% less than 'full' frame rate.

To better understand why integrators choose what they did, weasked them to explain their choices.

Integrators using an average of less than 5fps cited:

"Storage and network requirements" "Enhance the time stored on hard drives" "Cost of storage" "Most clients want to record at higher frame rate until you tell

them how much storage they will need. At that point, we tellthem how much storage their budget will allow and then weback into the frame rate."

"Storage may be cheaper but not so cheap to justify morethan 5FPS that often"

Not surprisingly, this group is motivated mostly by the cost ofstorage.

Let's compare to integrators using an average of 6 - 10 fps whorepresented the majority of respondents:

"Quality pics and small storage requirements -- a happymedium."

"I don't find any need to go higher than 10 FPS unless theyhave a LOT of additional storage that they don't require."

"A balance between storage and seeing all the event"


"This is all the operator needs to get a very good image" "We keep it at 8fps to get fluid video on playback" “6 to 10 fps is fast enough to provide adequate detail in a fast

action event (e.g. a running suspect, or an assault/batterytype of incident) and this is even more true if the LIGHTING ISADEQUATE AND PROPER. I'd rather have the customer spendmoney on good lighting and have medium frame rate videorather than a faster frame rate with crappy lighting."

The 6 - 10fps respondents are the 'balanced' group - use a highenough frame rate for an acceptably smooth video display but saveon storage costs.

Now let's compare to the 11 - 19 fps respondents:

"Customer requirement" "Detail and clear info required" "Getting play video close to real time is a big key. Sometimes

you might miss an event if you are doing anything less than 10fps. (i.e. someone stealing a can of beans)"

"Less than 11 FPS might yield erratic motion, but more than15 FPS consumes too much bandwidth/storage."

"Depending on the cameras location for more important areasor tight shots we run at 15fps. PTZs 15FPS. Large areas or lessimportant areas 5FPS or less"

The 11 - 19 fps group is more demanding and often driven bycustomer requirements. Equally important, this group is stronglycorrelated with larger camera count deployments (we crossreferenced this to average camera count deployed per integrator).


Finally, let's look at the smallest group - those choosing 20fps orgreater on average:

"Casino and cash counting require" "Unfortunately, although much less fps is enough to capture

all required information, it doesn't look "sexy" for most of ourcustomers. They want to be able to retrieve full motionvideo."

"Client defined"

The few votes and comments we received are consistent with nichedemands of specific applications or customers.

Is Megapixel Impacting Frame Rates?

Integrators who use more SD cameras than MP use a modestlyhigher average frame rate than integrators overall. For instance,while 70% of all integrators use less than 10fps, only 50% ofintegrators using primarily SD cameras record an average of 10fpsor less. Definitely, using MP cameras plays a role in limiting framerate but it is partial role. While the mid-point for all integrators forframe rate selection looks to be about 7-8fps, even for those whouse mostly SD, the midpoint is only modestly higher at 10fps.

Conclusion

6 - 10 fps is the average frame rate used for surveillance recording.It makes a lot of sense because it provides a fairly smooth playbackwhile minimizing storage costs which are still a real factor for theoverwhelming number of deployments.


To learn more and see examples of different frame rates in action,see our Frame Rate Training report and the 30 vs. 60 FPS shootout.

http://ipvm.com/report/training_frame_rates_for_ip_cameras

http://ipvm.com/report/testing_60_fps


Shutter Speed / Exposure Tutorial

Surveillance users do not need to be photography experts butunderstanding the basics of shutter speed is critical to avoidingmajor low light problems. Often, surveillance video will appearblurry and objects will look like ghosts - all due to issues withexposure. Here's an example:

In this tutorial, we explain the role of exposure and setting shutterspeed has in surveillance including a 5 minute video screencast toshow you the key issues in action.

Automatic vs. Manual Shutter SpeedSurveillance cameras almost universally default to automaticcontrol of the shutter speed, meaning that the camera willcontinue to adjust its speed without any intervention of the user. Ifit is really bright out, the shutter speed will be faster but if it isquite dark, the shutter speed will become slower. Normally, thisjust works and should be left alone.

http://ipvm.com/report/how_exposure_impacts_low_light_video_surveillance



Shutter Speed / ExposureShutter speed refers to how long the sensor is exposed to light.Exposure consists of shutter speed ('how long') and iris opening('how wide'). In this tutorial, we focus on shutter speed. In futuretutorials, we will examine iris controls and openings (F-stops).

Range of Shutter SpeedsShutter speeds can range from extremely fast (1/10,000 of asecond) to extremely slow (1/2 of a second). Since shutter speedsare almost always controlled automatically, the only part that iscommonly an issue is when the shutter is extremely slow.

Moving objects in a camera with a slow shutter (even 1/15 of asecond) can blur significantly, leaving the image useless. However,cameras will allow this because otherwise the image might be pitchblack, perhaps even more useless. See our report on "HowExposure Impacts Surveillance" for more examples and discussionhere.

Exposure in ActionWatch the 5 minute video below for demonstration of differentshutter speeds and dealing with slow shutter settings.

Setting Cap on Slowest Shutter SpeedThe most important thing you can do with shutter speed is todetermine what the slowest shutter speed you are willing to allowand then configure this as a 'cap'. You will need to experiment tofigure out what works in each specific application and based onyour quality needs (e.g., capturing license plates on a moving carmay need 1/100s but capturing the profile of a parked car could befine with 1/2s). Once you know what that slowest shutter speed is,




go into the camera's configuration and enter that in. This isimportant as many cameras default to very slow shutter speedsthat might result in unacceptable video for your specific scenario.

Options for Fixed Shutter SpeedProfessional cameras often allow advanced controls for fixing theshutter speed of a camera. Do not do this unless you havecontrolled, constant 24/7/365 lighting. In those circumstances,fixing the shutter speed can help ensure the video quality does notchange. However, if the lighting were to vary (darker or brighter),the image quality could become bad very quickly.

Advanced Tricks - Sens UpNow that you have gone through the fundamentals, see howshutter speeds can be gamed by manufacturers in our post - SensUp is for Suckers.




Testing: Gain / AGC Impact onSurveillance Video

Gain control is a critical, though often overlooked, factor in lowlight surveillance video. It is generally only noticed when thenegative side effective of aggressive gain levels are seen, namelynoise / snow on screen. The picture below, from one of our parkinglot tests, is a prime example of this problem:

Clearly, the noise is a problem and ideally you would want toremove it. This raises important questions about how to use gaincontrol effectively.

In the introductory video below, we provide a real timedemonstration of gain control:

http://ipvm-uploads.s3.amazonaws.com/uploads/b8c2/90b8/noise-sample.jpg


To learn more we conducted a series of experiments in a variety ofscenes. For each scene, we captured video, images and bandwidthconsumption. Here are the scenes we tested:

Black and White Mode .5 Lux (Dark) Black and White Mode 20 lux (Low Light) Color Mode 4 Lux (Moderately Dark) Color Mode 300 Lux (Daytime)

Our testing was done across 3 HD cameras from Avigilon, Axis andBosch to see a range of performances.

We share our results and answer the following key questions:

How significant does image quality vary with different gaincontrol settings?

Should you use gain control? What are the correct gain control settings to use? What alternatives should you seek to use gain control? How does manufacturers approach to gain control differ? How does gain control differ between Black & White and

Color modes? What is the bandwidth impact of different gain control

settings? What impact do light levels have on bandwidthimpact?

What impact do VBR and CBR streaming modes have on usinggain control?

Key FindingsLet's start with the key findings of our tests:


Gain Control Very Important: In almost any night time scenes,without gain control, surveillance video would be very dark andalmost practically useless. While gain control is generally ignored,its role is critical. In low light conditions, trying to turn it off toremove the grain/noise will only result in far worse video quality.

Gain Control is Automatic: As the name states, Automatic GainControl, is automatically controlled by almost every camera. Whileit can produce lots of noise, disabling it generally will make thingseven worse.

Aggressive AGC: Unlike in commercial videography where gaincontrol is used minimally and in moderation, surveillance cameramanufacturers tend to use massive amounts of gain control. This isnecessary because unlike in film shooting, it is very hard to controlscene lighting in surveillance.

Adjusting Gain Control: If you want to minimize the bandwidthimpact and visual noise inherent in gain control, the two gainadjustments possible are (1) fixing the gain or (2) capping the gain.The former is dangerous unlike you can guarantee constantlighting. The latter, assigning a cap, can be useful.

Gain for B&W and Color: Both B&W and Color modes use gain anddisplay similar characteristics - bandwidth spikes, visual noise, etc.The big difference is that cameras activate gain at much higher lightlevels for color than in black & white modes (color at ~50 lux, b&wat ~20 lux).

Gain and Bandwidth Increases Tightly Correlated: As gainincreases, bandwidth increases as well in a hockey stick curve.Interestingly, this appears to occur regardless of the light level ormode used.

Use CBR or VBR with a Cap: Since bandwidth is nearly guaranteedto spike as gain increases, consider using CBR or VBR with a

http://www.productionapprentice.com/featured/the-truth-about-video-gain-and-how-to-use-it-properly/

http://www.productionapprentice.com/featured/the-truth-about-video-gain-and-how-to-use-it-properly/


bandwidth cap to minimize the negative side effects of gaincontrol.

Below is a video that shows and explains our key findings withreferences to our test video and images:

Configuring and Optimizing GainGain is generally controlled by two modes:

Levels: For example, high, medium, low - this is a coarsegrained control.

dBs: For example, 0dB, 15dB, 30dB, etc. A fine gain control,the range tends to be from 0dB (off) to 30dB (very aggressive).In addition to these modes, two options are sometimesavailable:

Fixed: By default, most cameras automatically determinewhat level gain should be. As an alternative, a user can lockgain to a specific level (e.g., always 6 dB). This can bedangerous - if you do this at too low a level (like 6dB) and thescene becomes even moderately dark (say 5 lux), the imagequality is going to be quite poor. On the other hand, if you setit at a high level (say 27 lux) and the scene becomes bright,the image will be distorted by heavy grain / noise.

Cap: Some cameras allow the admin to cap the maximum gainthe camera can choose. This allows the camera the autonomyto fluctuate the gain but blocks it from going too high for anadmin's preference. This can be useful for reducing somevisual noise and reducing bandwidth spikes. However, of


course, keep in mind such caps will make the imager darkerthan possible with max gain.

The video below provides demonstrations on how to use andoptimize gain using Axis and Bosch cameras as an example:

Varying Gain Control DemonstrationsTo get a sense of how gain impacts overall video quality, the belowcomparisons show the same scene with the same lighting withdifferent gain levels. The top image has the maximum amount ofgain with each descending image at a lower gain level. Take a look:


http://ipvm-uploads.s3.amazonaws.com/uploads/33b6/7506/impact-varying-gain-half_Lux.jpg


In the above scene, almost anyone would agree that the top imageis the best. With this dark scene, high gain becomes critical to makeanything out. Indeed, even with 3dB of gain, the scene is pitchblack.

Let's contrast to another slide below with 40x the amount of light.Take a look:


http://ipvm-uploads.s3.amazonaws.com/uploads/a68f/9944/impact-varying-gain-20-lux.jpg


Which do you think is better? This one is certainly much morecomplex than the first slide with sub 1 lux lighting. In this scene,with 20 lux, the image with maximum gain is somewhat dark andsuffers from a lot of visual noise. The images actually look betterwith less gain; though one could debate which of the low gainimages were best. As a point of reference, we estimate thiscamera's automatic gain setting for this scene to be about 6 to 9dB.

Color Mode - Gain ImpactThe same tradeoffs with gain variance occur with color mode. Thebig difference, as the comparison below shows is that with color,gain is needed more even at higher light levels. By default, at 4 lux,all 3 cameras automatically adjusted their gain control to maximumlevels. You can see this with the clear visible noise across eachimage.

By contrast, with gain disabled, the images are significantly darkerand the colors are more subdued (Bosch), missing (Avigilon) oraltered (as in the case with the Axis camera).

http://ipvm-uploads.s3.amazonaws.com/uploads/1de8/b6eb/color mode-max-vs-disabled.jpg


Gain's Impact on BandwidthOne of the most oft cited problems of low light surveillance isincreased bandwidth consumption. Perhaps the most interestingfinding of this test is the strong correlation of gain levels andbandwidth, regardless of the mode of the camera or the light levelof the scene.

Below is a chart that depicts the relationship. The numbers arebased on .5 lux B&W mode for Axis though the same pattern wasdisplayed with higher light levels, color mode and the Avigiloncamera.

The bandwidth penalty becomes increasingly steep as gain levelsincrease. We have noticed some cameras with very high noise andvery high bandwidth consumption in low light. This looks to be anoutcome of manufacturer choosing aggressive maximums forautomatic gain control.

http://ipvm-uploads.s3.amazonaws.com/uploads/e9c1/d230/bandwidth-vs-gain-chart.png


Based on this, we recommend you check your low light bandwidthconsumption. If it is quite high, see if a gain control cap exists andtry lowering it from the manufacturer's default maximum.

The other option is to use CBR streaming or VBR with a cap ofmaximum bandwidth. The image below shows our test results oftaking a scene with maximum gain and limiting its bandwidth to 1Mb/s. The overall image quality is practically unchanged but at afraction of the bandwidth.

Gain's Impact Across CamerasFinally, here is a summary comparison of gain across light levels,gain settings and cameras tested. Take a look and compare thedifferences yourself. Perhaps the most interesting element we sawhere was that with bright light (300 lux at the bottom of thecomparison), the Avigilon appears to provide the sharpest imagedetails. However, with low gain, Avigilon's image essentiallydisappears.

http://ipvm-uploads.s3.amazonaws.com/uploads/711c/e22c/bandwidth-impact-max-gain.jpg


http://ipvm-uploads.s3.amazonaws.com/uploads/b5c4/c2e2/dollar-bill-comparison.jpg


WDR Tutorial

WDR is one of the most important and highly differentiatingcapabilities of surveillance cameras, critical to ensuring strongimage quality in many real world applications. However, anymanufacturer can claim WDR, and many do even if actualperformance is weak. In this tutorial, we break down WDR:

What is WDR? How Do You Measure WDR? Camera WDR Challenges WDR vs. Resolution WDR Implementations

Our TestsThis tutorial summarizes and explains key points on WDR. For thosethat want to see the testing and analysis in depth, see our WDRShootout and Megapixel WDR Shootout.

What is WDR?WDR is the ability to produce high quality image across a range oflight levels. The term stands for 'wide dynamic range' with the widereferring to the range of light levels. Alternatively, but less commonin surveillance, HDR or 'high dynamic range' is used. Both terms, insurveillance, essentially refer to the same ability.

WDR can make a big difference. Here's an example of a personwalking in a doorway:

http://ipvm.com/report/wdr_mega_shootout

http://ipvm.com/report/wdr_mega_shootout

http://ipvm.com/report/wdr_surveillance_test


Now, the image below demonstrates what we mean by light levels:

The single scene has a very bright middle and far less bright sides.

Measuring WDRIt is critical to know how wide the range of light levels a scene has.The generally accepted term in surveillance to measure this is thedecibel (e.g., 58dB, 113dB, etc.) with higher levels indicatingstronger WDR performance. Unfortunately, these measurementsare not standardized, at the discretion of each manufacturer andshould not be trusted upon.


While dB measurements alone are fairly critical (i.e., what does itmean physically?), they are grounded on a specific test scenario. Agrayscale chart is used with numerous shades from white to black.The more levels a camera can display/capture, the higher its dBrating and the better its WDR performance should be. Below is anexample image from Pixim's WDR measurement whitepaper:

Unfortunately, this does not translate well to read world scenes(i.e., what can I expect for my front door camera?) nor is thisapproach guaranteed to be used or measured fairly by allmanufacturers.

An Alternative ApproachIn our testing, we have developed an alternative real worldapproach to measuring how tough a WDR scene is. Using a luxmeter, we record the brightest and the darkest spots of eachscene. The ratio of the two provides a strong indicator of howchallenging the scene is.

http://ipvm-uploads.s3.amazonaws.com/uploads/6ba9/d5ea/pixim-wdr-paper.pdf


In a doorway opening outdoors, with a small opening to anenclosed area, the range is typically quite high, as shown below:

The WDR ratio is ~6.5x, with the open doorway at 1300 lux and theadjacent indoor sides at ~200 lux.

The closer one gets to a WDR ratio of 1, the less likely that WDRcapability is needed. Moreover, the lower ratio the less powerfulWDR functionality one needs.

Of course, even with our approach you will need to measure butthis can be done by a field tech with a $100-$150 lux meter.However, do make sure to do this when the sun is strongest as theWDR ratio will vary throughout the day as the sun moves.


Camera WDR ChallengesNormal cameras typically struggle with wide ranges of lightingbecause of their dependency on a single exposure. Cameras needlight to generate an image. However, too much light and the imageis washed out yet too little light and the image is too dark.

If you have a scene with even lighting, it is no problem. The camerawill simply adjust its iris opening size or its shutter speed to get theright amount of light. This is why manufacturers typically demotheir cameras in even lighting scenes.

However, if the scene has a wide range of lighting, the camera hasa tough challenge. If it restricts the amount of light it takes in tooptimize for the bright areas, the lower light areas will be too dark.However, if it chooses the opposite approach, optimizing for lowlight areas, the bright side will be washed out. The image belowshows this tough tradeoff:

Something, therefore, needs to be done to overcome this.

WDR vs. ResolutionInterestingly, it turns out that higher resolution improves WDR.This is NOT the best nor the most sophisticated approach (seemore below). However, increasing the number of pixels helpscapture finer details even in the darker / brighter areas. See anexample from our tests:


The worst is the SD, even though it is a true WDR. The 5MP nonWDR beats it simply because it captures more details. Finally, theHD camera with true WDR performs the best.

While more pixels can hurt night time imaging, it helps WDR. It isan important element in understanding today's top performingWDR cameras. However, he biggest one for 'true' WDR cameras ismultiple exposure functionality.

WDR Implementations - True vs. FakeSince the main challenge for WDR scenes is setting the exposureappropriately to capture both dark and bright areas, the mostcommon viable solution is to use multiple exposures and thencombine them to produce a better quality image. The shortexposure captures the bright areas, while the long exposurecaptures the dark areas. See representation below:


In our testing, this is the core strength of all top performing WDRcameras.

While we recommend looking for WDR cameras using multipleexposures, this is not sufficient. The number of exposures used andthe other image processing techniques implemented can also makea difference. However, none of these are typically revealed.

Multiple Exposure Issues in Low LightA common downside of multi-exposure WDR implementations isworse performance in low light. Using multiple exposures typicallyrestricts how slow a shutter can be set. However, when it is darkat, slower shutters bring in more light, producing a brighter image(though go too far and you have bad motion blur).

When using WDR cameras, make sure that WDR is disabled at nightfor maximum low light performance. Some cameras do thisautomatically, others allow for manual configuration and a fewhave no option. This is an important element to check if low light isa priority for the location deployed.

PiximPerhaps, the best known classical WDR cameras use a Pixim chip.Pixim says they set the exposure individually for each pixel, ratherthan just using 2 or 3 exposures for the whole scene. While thismany deliver better image quality in an SD only world, Pixim has noMP offerings. In our testing, true MP WDR cameras have surpassedPixim. [Note: In 2012, Sony acquired Pixim and there may be newPixim HD offerings in the future but nothing is announced.]

Other Pseudo-WDR Techniques



http://ipvm.com/report/sony_acquires_pixim


Two other pseudo-WDR techniques are often claimed bymanufacturers as being alternatives. However, they are weak onesat best:

BLC, or back light compensation, simply adjusts the (single)exposure of a camera. This is useful only when you want to capturejust the bright or dark areas of the scene but not both. By usingBLC, you will make one portion of the scene at the expense of theother worse.

eWDR, or electronic WDR, represents image processing attemptsthat do not come close to true WDR capabilities. Be careful if yousee claims of 'eWDR' or electronic based WDR.

Same Manufacturer - WDR vs. Non WDRWhen a manufacturer offers 'true' WDR, that version typicallyoffers substantially better performance in harsh lighting conditionsthan the non WDR version. On the other hand, it is often costs afew hundred dollars more than the non WDR version.

Here is a comparison of Axis WDR vs. non WDR:

And here is a comparison for Sony:


Note: Do not compare the Axis and Sony as these shots are fromdifferent tests/times. For head to head comparison, see the Axis1604 vs. Sony WDR results.

Even within a manufacturer line, be careful of how manufacturersuse the term 'WDR' to market their cameras. See this exampleof Axis WDR vs. WDR.

http://ipvm.com/report/axis_q1604_test_results

http://ipvm.com/report/axis_q1604_test_results



LENSES


Lens Focal Length Tutorial

Camera specifications often list lens length: 3mm, 6mm, 2.8 - 9mm,etc. These metrics are important in determining the correct cameracoverage and Field of View (FoV). In this tutorial, we look at:

What lens length impact The relationship of imager size Common lens length ranges and their uses Picking the right lens length

Lens Focal Length ImpactThe longer the lens, the narrower the Field of View / area captured;the shorter the lens, the wider. This is a physical principle derivingfrom the distance between the lens and the imager, as the imagebelow shows:

The longer the lens is, the farther it is away from the imager,resulting in a narrower FoV. Likewise, if the lens is very short, it willbe extremely close to the imager and capture the widest possiblearea.


The relationship between lens length and Field of View is linear. Ifyou double the lens, the Field of View will be cut in half, i.e., a 6mmlens will cover half the Field of View as a 3mm one.

However, it is somewhat confusing and unintuitive to measure thisin the millimeters of the lens length. It would make more sense toexpress it in angle (i.e., 80° instead of 3mm, 40° instead of 6mm).

Impact of Imager SizeThe size of imager used (i.e., ¼”, 1/3”, 1/2”, etc.) also impacts theField of View / area covered. Everything else equal, the larger theimager, a larger FoV / area can be captured.

This is not a huge factor as most professional surveillance camerasare 1/3” (or close – at 1/3.2” or 1/2.7”). However, it is enough thatexpressing the FoV of lens in degrees can be slightly inaccurate.This is a major reason why millimeters is used instead of degreesand is something that needs to be appreciated / factored in whenreviewing lenses.

Rule of ThumbUsing the most common 1/3” imager, here is the FoV in degrees forcommon lens length:

3mm - 85°6mm - 44°12mm - 23°20mm - 13.7°50mm - 5.5°


Try these calculations on your own using a lens calculator.

Common Lens Length RangesIn practice, surveillance cameras typically fall in one of 4 lens lengthranges:

Fisheye – Under 2mm provides super wide angle views butcomes with distortion, ergo the name ‘fisheye’. These lensestypically require dewarping software to provide a flat /corrected image. While it can provide panoramic images,implementation constraints remain. See our Guide toselecting Panoramic / 360 fisheye cameras.

‘Normal’ – 3mm – 10mm: The stock lenses of most camerasfall in this range (roughly 30 to 80 degrees FoV).

Telephoto – 10mm – 80mm: While most cameras do no comewith lenses in this range, lots of 3rd party C/CS lenses can bepurchased and connected to cameras (typically box formfactor)

Super Telephoto - 100mm+: Lenses in this range are specialistones used to see / monitor objects very far away (typically1km+ plus often 5kms or more)

Lens LimitationsThe longer the lens length, the more likely two limitations willarise:

Degraded low light performance: Very long lenses (as well asvery short ones) typically capture significantly less light thannormal lenses in the 3mm to 10mm range. Specifically,everything else being equal, the longer the lens the higher theF stop (Review our F stop tutorial for details).

http://ipvm.com/report/training_lens_calculators





Depth of Field Issues: Surveillance cameras very rarely havedepth of field issues where objects appear out of focus. This isbecause they usually use relatively short lenses and havesubjects that are more than 5 feet away from the camera.However, very long lens will cause problems that areespecially hard to resolve for night time imaging or with auto-iris lenses. Review our Depth.

Picking the Right Lens Length

The shorter the lens length, the more the camera can capture.Unfortunately, the wider the capture area, the less detailed is anyindividual object captured. This is why people often are stunnedwhen they look at a megapixel fisheye camera. Since it ismegapixel, the quality should be better but since the FoV is sohuge, all the objects look 'fuzzy' even if they are close to thecamera.

The easy rule of thumb is to make the FoV no wider than the areaof interest – i.e., just what you care to capture. However, this canbe tough as people want to capture a lot of things (i.e., I want thecars in the parking lot plus the license plates of the cars entering it).

To help solve this, Pixels Per Foot (PPF) is the metric used to helpdetermine how wide one can go without making the details in thearea captured so fuzzy that they have no value. Please read our PPFGuide to understand this.




Field of View (FoV) Tutorial

Field of View, or FoV, is deceptively complex. At its most basic, it issimply what the camera can 'see' and is, therefore, visually self-evident. However, when analyzing images, comparing cameras orprojecting quality, FoV subtleties can have a big impact. In thistutorial, we examine:

Calculating Field of View Measuring / Comparing the Right Field of View Field of View vs. Distance from Camera Field of View vs. Lens Length

Calculating Field of ViewThe first step is calculating a camera’s FoV. The key factor here islens length. The longer the lens, the narrower the FoV / area thecamera can see. One specifies the appropriate lens length for theFoV they desire.

To see what different FoVs with varying lens lengths 'look' like,use Supercircuit's FoV comparison tool. Here's a comparisonoverview:

http://www.supercircuits.com/resources/tools/fov-comparison-tool

http://www.supercircuits.com/resources/tools/fov-comparison-tool


For more, review our tutorial on lens length that explains this indepth. Once you understand lens length, you can calculate FoVusing a lens calculator. Review our tutorial.

However, knowing your FoV alone is insufficient as you need toappreciate how it relates to other cameras and objects within theFoV.

Measuring / Comparing FoVThe most common FoV problem we see is comparing cameras withdifferent FoVs. Even if the cameras are identical and are looking atthe same object, the camera with the wider FoV will always ‘look’worse than the other one. Likewise, if you want to unfairly make apreferred camera look better, show that camera in a narrower FoV(see the Arecont ad as an example).

The comparison below shows two different FoVs being swapped:

It does not need to be vendor manipulation. Often, people willsimply test two different cameras at two different times and notverify that the FoV of the cameras are the same.


http://ipvm.com/report/arecont_lies_now_threatens_lawsuit


A wider FoV can result from a shorter lens length or a subjectfurther from the camera. We now examine both.

Field of View vs. Distance from the CameraThe further a subject is from a camera, the wider the FoV is at thatpoint. This is essentially a mathematical law. You can see itphysically in the image below with:

Here's an overhead shot that demonstrates the same principle /scene:


Because of this, three important lessons must be remembered:

There is no single FoV width. While people often imply this, itis a dangerous assumption because you must know where inthe FoV a target is. Saying simply the "FoV width is X' ismisleading.

To define the FoV width, you must know the subject'sdistance from the camera. To properly define this, say "TheFoV width ix X at Y from the camera.'

Make sure you understand the farthest point away from thecamera one wants to monitor. By definition, this will be thewidest FoV and the most likely to have problems deliveringsufficient details. To determine if the FoV is too wide, use PPFas a guideline.

Field of View vs. Lens LengthNot only does a shorter lens length increase the FoV, it alsoaccelerates how much the FoV increases as the subject’s distance




from the camera increases. Let’s compare a fisheye/panoramic FoVwith a super telephoto one to show this principle in action:

For a 360 / fisheye camera, every 1 foot a subject is further fromthe camera, the FoV increases ~6 feet (as the FoV is the perimeterof a circle). In just 10 feet, the FoV is more than 60 feet wide.

By contrast, for a super telephoto lens, every 1 foot a subject isfurther from the camera, the FoV may only increase one half orquarter of a foot. Because of this, a subject who is 10 feet behindanother will have a very similar FoV with a super telephoto lensand likely similar detail captured. This is exact opposite of thefisheye / 360 camera.

Lessons to take away:

Be very careful with fisheye or super wide angle lenses as theFoV will expand rapidly, capturing limited details across theirwide range.

While super telephoto lenses deliver a FoV width thatexpands slowly, shallow depth of field becomes a big risk. This


lens type might deliver the necessary PPFs but still be out offocus. See our Depth of Field tutorial for details.

That noted; most cameras with ‘normal’ or common lenses (in the3mm to 8mm range) will have their FoV widen ~1 foot for every 1foot increase in subject distance from the camera. However, at theextremes, the difference in FoV expansion can vary dramatically(i.e., fisheye and super telephoto).



Varifocal vs. Fixed Lens

When selecting lenses for surveillance cameras, there are twofundamental options: varifocal and fixed focal length. Varifocallenses allow the field of view to be adjusted within a range (e.g. 3-8mm, 9-20mm, etc.) after the camera is installed, without changinglenses. Fixed focal length lenses are just that, offering only onefocal length. As part of our Fall 2011 integrator survey, we aimed tofind out which of these two options integrators were most ofteninstalling.

We asked the following question of 84 integrators:

The ResponsesThe vast majority of integrators (88%) preferred varifocal lenses tofixed focal length. Most commonly, flexibility and simplicity werecited as the reasons for this preference.


Flexibility of FOVThis was overwhelmingly cited as the number one reason forchoosing varifocal lenses. Unlike fixed focal length lenses, varifocallenses allow the field of view to be changed after the camera isinstalled, without changing the lens. This is often critical. Ifconditions on site differ even slightly from how they were when apre-installation site survey was performed, it may affect lensselection drastically. Varifocal lenses allow fine-tuning to accountfor these differences, as well as customers simply changing theirmind.

Here are some comments from integrators on the topic:

"We prefer the varifocal lens b/c it allows our customers to'change their minds' of what they want to look at vs. havethem pre-determine their shot before we complete the install.This gives everybody more lee-way."

"Allows flexibility to change view based on changes made atlocations after the initial installation."

"This type of lenses minimizes the time of site survey and alsoin the future we are able to change the camera viewaccording to any modifications to the site or the request fromthe client."

"Varifocal is easier to use as well as it doesn't lock you into aspecific field of view. Customers change their mind and salespeople don't always calculate the angles correctly."

"Flexibility. If you can move a camera to another positionwhen needed, that makes the equipment selection processless final. They know they can change their mind later, orrespond to an unexpected situation."


Ordering SimplicityIntegrators also cited simplicity in ordering and stocking as a reasonfor choosing varifocal. Instead of stocking simply a 3-8mm varifocallens, an integrator may instead need to stock 3mm, 4mm, 6mm,and 8mm fixed lenses. This is obviously more work in ordering andmaintaining inventory. In the same amount of space, an integratormay stock one or two varifocal lenses which cover nearly allapplications.

Integrators had the following to say:

"Easier to use to get the field-of-view that the customer isexpecting. It also reduces the complications associated withordering cameras."

"Gives our customers the option to zoom in or out after laterwithout replacing lenses. Standardized purchase orders frommanufacturers translate into less for work sales staff and lessequipment on our shelves and vehicles."

Proponents of Fixed LensesOf the integrators who preferred fixed focal length lenses (12%),most commonly they cited better performance as their reason forselecting fixed lenses.

Integrators preferring fixed focal length lenses had the following tosay:

"It depends on the application. I prefer fixed lenses becausethey are less costly and usually optically better than varifocal.They also theoretically should take less time to adjust since


there is no zoom adjustment to contend with. However, thevarifocal option is very handy when a customer is indecisiveabout the scene they want to see or is prone to relocatingcameras. WYSIWYG does not always sit well with customerswhen they are paying a premium for an IP system."

"These are much easier to focus while using manual-focuscameras. Varifocal are only used when no one can make uptheir mind ahead of time as to where the cameras should belocated or what they should see."

"Fixed focal lenses offer a much clearer view and with HDcameras the limitations of vari-focal can show up"

RecommendationsIn most cases, varifocal lenses are likely a better option. Theflexibility and simplicity they offer will almost always outweigh thepotential advantages of fixed focal length lenses. For one, fewoptions exist for various focal lengths in fixed lenses, especiallyunder 3MP. This greatly limits selection. Additionally, in preliminarytests of Tamron fixed and vari-focal lenses, we saw no clear opticaladvantages to using fixed focal length lenses.


Focusing Tutorial

This tutorial explains the fundamentals of focusing including:

The two fundamental controls - fine focus and zoom How and where to focus Field issues Options for auto focusing

We focus on varifocal lenses, the most popular and commonly usedtype for professional surveillance cameras.

Two Fundamental ControlsWhen manually controlling the focus, two common controls exist:

Fine Focus - which adjusts the focus itself Zoom - which indirectly impacts focus for lenses that allow the

Field of View to be adjusted (common in surveillance)

Typically those controls are placed next to each other, with the finefocus farther away from the camera and the zoom closer. Theimage below shows this:



Here's another view from the side:

On lenses that support manual adjustment of the iris, a thirdcontrol is available to adjust the opening of the iris, as shownbelow:


Since the iris controls how much light is let in, adjusting it will notaffect the focus. However, make sure you do not change this bymistake when you are focusing. Also, in most circumstances,manual iris lenses should be kept 90%+ open to maximize theamount of light captured at night or else you will have surprisinglybad low light images.

How to FocusAlways try to zoom before you fine focus. That said, it can be veryeasy to mistake them, especially if you reaching out or over in acramped place. Also, when adjusting the zoom, the image canbecome extremely blurry and you may not be able to determinethe zoom level. At that point, you may need to fine focussomewhat to get a sense of your current FoV and then continuingadjusting as needed.

Where to FocusIf you bench test your cameras, you should try to get them in roughfocus before you install them on site. While you will likely need to



adjust the zoom level in the field, having them somewhat focusedwhen installing, at least help you see how close the FoV is toneeded when you make on site adjustments.

Field IssuesThe biggest problem with focusing in the field is that cameras areoften installed in high, difficult to reach places often outside. Thecombination of these two makes focusing much harder than doingso on an office table. Plus, IP cameras, unlike analog, typically donot connect simply to cheap monitors. Review available IP camerainstallation tool options and issues.

Auto FocusingAn increasingly popular capability in IP cameras is the ability toautomatically fine focus the camera with a push of the button onthe camera or remotely via a web interface. The video below showshow to do it and the options available:



http://fast.wistia.com/embed/iframe/3k1nc1u2ba?autoPlay=true&popover=true&version=v1&videoHeight=480&videoWidth=640&volumeControl=true


Auto focusing is increasingly popular and we recommend it, bothfor simplifying installation and ensuring higher quality over the longterm. However, cameras with it are typically more expensive andgenerally available on higher end lines.

The feature is sometimes called auto focusing and other times autoback focusing. While a technical difference does exist, the corefunctionality and benefits are the same. Box cameras typicallyfocus by moving the imager back and forth (ergo'autoback focusing') while dome cameras usually do so byautomatically adjusting the lens. Most users can ignore thedifferences in implementation though domes often combine autofocusing with small range of zooming which can be useful foradjusting the FoV width remotely - a nice addition.



F-Stop Tutorial

To understand low light surveillance, appreciating the importanceand role of the f-stop metric is critical. In this tutorial, we explain:

Why minidomes and other small form factor cameras typicallyhave far worse f numbers

How the range of a PTZ impacts its f-stop / low lightperformance

Why adjusting f-stop to maximize depth of field is dangerousand unlikely to help much in surveillance

How f-stop can be confusing and counterintuitive

Key PointsF-stop measures the relative amount of light that a lens can pass.Understanding the number's significance can be tricky as the biggerthe F number (1, 2, 4, 8, etc.), the less amount of light will be pass(e.g., 8 is much worse than 4, 1.8 is worse than 1.2, etc.). Here's avisual illustration of lens openings vs. F numbers:

Technically, f stop contrasts the length of the lens and the diameterof the iris (i.e., L/D). The longer the lens (say 10mm instead of3mm), the less light passed and the higher the f number. Similarly,smaller lens diameter (such as found in miniature cameras)narrows the maximum iris, allowing less light to pass, resulting in


higher f numbers. Both of these elements impact practicalsurveillance selection, especially in PTZs and minidomes.

What F Numbers Mean on SpecificationsWhen lenses / cameras specify F numbers, they always provide thelowest F number that the lens supports when the iris is all the wayopen. Most lenses can adjust their iris opening. When narrowed,the F number will be higher. However, once the iris is opened allthe way, the physical limitation is the width of the lens itself. It isthis lowest F number, with the iris all the way open, which is mostcritical when assessing the low light capability of a lens.

Differences in F numbersThe difference between f numbers can be deceiving and muchbigger than if one assumes a straight line relationship. For instance:

f/2.8 takes in 75% less light than f/1.4 f/5.6 takes in only 1/16th the light as f/1.4

Use this f-stop calculator to try for yourself.See the calculator in action in this short video below:

RecommendationsWhile it is important to be aware of F-stop and the impact it canhave:

Small differences in F numbers (e.g., f/1.2 vs. f/1.4) generallydo not impact low light performance significantly, contrary towhat is commonly advocated. Automatic and other camera sideimage processing offset small f number differences.


http://imaginatorium.org/stuff/stops.htm


Most professional MP box cameras have F-stop numbers of1.2 or 1.4.

Just because cameras have similar F-stop numbers, does NOTmean their low light performance will be the same.Differences in imaging processing make a material differenceplus manufacturers often use slow shutter tricks.

However, F stop numbers of 2.0 or greater often indicate poorlow light performance.

Minidomes and other small form factor cameras typicallyuse small lens, with narrow lens diameters, that have high fnumbers and typically worse low light performance (f/2.0 orgreater). For instance, Axis full size domes (P33) have a f/1.2while their minidomes (M30) have a f/2.8, meaning theminidomes take in ~1/5th the amount of the full sized ones.

PTZs when zoomed to see far objects (i.e., long focal lengths)typically have high F numbers and poor low light performancesince zooming out requires a long focal length (often 80 or100mms) at a high F number (f/3.0 or greater is common).Beware many manufacturers do not list this but it is inherentwhen the diameter stays the same but the length of the lens isincreased.

Depth of Field ImpactWhile high F numbers are bad for low light, they can be helpful forincreasing the depth of field but not typically in surveillance (seeour depth of field tutorial). The higher the F number, typically thegreater the depth of field. The image below demonstrates potentialbenefits:


http://www.axis.com/files/datasheet/ds_p33_v_indoor_45847_en_1207_lo.pdf

http://www.axis.com/files/datasheet/ds_m30series_48295_en_1207_lo.pdf



While this may be helpful for photography, it typically does notmake a big difference in surveillance. Worse, it can destroy thecamera's low light performance. For example, compared to f/1.4common in surveillance cameras, f/8.0 takes in 32 times less light.If this was left on at night, in a dark environment, the camerawould literally capture nothing beyond pure blackness. Indeed, noauto iris camera would allow f/8.0 to be used in such conditions ascameras are programmed to open the iris as fully as possible whendark (i.e., to the lens min f number).

Our recommendation is to ignore depth of field optimization unlessyou have strong photography skills and are willing to risk negativeside effects for limited performance improvement (only during theday).

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm


Shutter Speed / Exposure Tutorial

Surveillance users do not need to be photography experts butunderstanding the basics of shutter speed is critical to avoidingmajor low light problems. Often, surveillance video will appearblurry and objects will look like ghosts - all due to issues withexposure. Here's an example:

In this tutorial, we explain the role of exposure and setting shutterspeed has in surveillance including a 5 minute video screencast toshow you the key issues in action.

Automatic vs. Manual Shutter SpeedSurveillance cameras almost universally default to automaticcontrol of the shutter speed, meaning that the camera willcontinue to adjust its speed without any intervention of the user. Ifit is really bright out, the shutter speed will be faster but if it isquite dark, the shutter speed will become slower. Normally, thisjust works and should be left alone.




Shutter Speed / ExposureShutter speed refers to how long the sensor is exposed to light.Exposure consists of shutter speed ('how long') and iris opening('how wide'). In this tutorial, we focus on shutter speed. In futuretutorials, we will examine iris controls and openings (F-stops).

Range of Shutter SpeedsShutter speeds can range from extremely fast (1/10,000 of asecond) to extremely slow (1/2 of a second). Since shutter speedsare almost always controlled automatically, the only part that iscommonly an issue is when the shutter is extremely slow.

Moving objects in a camera with a slow shutter (even 1/15 of asecond) can blur significantly, leaving the image useless. However,cameras will allow this because otherwise the image might be pitchblack, perhaps even more useless. See our report on "HowExposure Impacts Surveillance" for more examples and discussionhere.

Exposure in ActionWatch the 5 minute video below for demonstration of differentshutter speeds and dealing with slow shutter settings.

Setting Cap on Slowest Shutter SpeedThe most important thing you can do with shutter speed is todetermine what the slowest shutter speed you are willing to allowand then configure this as a 'cap'. You will need to experiment tofigure out what works in each specific application and based onyour quality needs (e.g., capturing license plates on a moving carmay need 1/100s but capturing the profile of a parked car could befine with 1/2s). Once you know what that slowest shutter speed is,




go into the camera's configuration and enter that in. This isimportant as many cameras default to very slow shutter speedsthat might result in unacceptable video for your specific scenario.

Options for Fixed Shutter SpeedProfessional cameras often allow advanced controls for fixing theshutter speed of a camera. Do not do this unless you havecontrolled, constant 24/7/365 lighting. In those circumstances,fixing the shutter speed can help ensure the video quality does notchange. However, if the lighting were to vary (darker or brighter),the image quality could quickly degrade.

Advanced Tricks - Sens UpNow that you have gone through the fundamentals, see howshutter speeds can be gamed by manufacturers in our post - SensUp is for Suckers.




Lens Iris Tutorial

Cameras, like humans, have irises. However, cameras have fourtypes of iris options - fixed, manual, auto and P iris. In this tutorial,we explain the tradeoffs of each, how irises work and how theyrelate to shutter speed.

Controlling LightCameras control light received by either adjusting the width of theopening (iris) or the length of time the opening is open (shutter).When the width of the opening (iris) is adjusted, its F numberchanges, reflecting that more (or less) light enters.

Here's what a lens iris looks like mostly open vs. mostly closed:

And here's a visual showing the process of adjusting:





If you let in too much light, the image will be washed out but toowith too little light, the image will be dark. Since light levels changeover time, the camera has to be able to adjust how much lightenters to match the current conditions. Irises are one way to dothis.

Comparing the Four Types of IrisesThe first two irises - fixed and manual - cannot be controlled by thecamera. Indeed, fixed iris, as the name implies cannot be adjustedat all. It is set at the factory, typically all the way open to its lowestF stop. By contrast a manual iris lens can be adjusted but only by aperson 'manually'. That noted, most manufacturers generallyrecommend setting manual iris lenses all the way open or 90%+open. Otherwise, low light performance is compromised.

The second two irises - automatic and P iris - can be controlled bythe camera. The key difference is how precisely the camera cancontrol the iris. P iris lenses can be controlled / set to specific F stoplevels while auto iris lenses are less granular.




Automatic and P iris lenses require cameras to support a physicalinterface / connector. Additionally, P iris lenses require specificsoftware driver support for the particular model being used.Combine this with P iris lens far lower availability and usinganything but the manufacturer provided P iris lens can causeproblems.

That noted, the two most common irises used in professionalsurveillance are manual and auto irises. The image below showsthe main visual differences between the two:

Auto and P irises look similar from the outside as both need a cableand connector to connect to the camera.

What To Use?In IPVM's tests, we have not found a major difference in imagequality between iris types. Higher end cameras tend to have eitherauto or P iris lenses so it may signal overall higher quality but we donot believe this is significantly driven by the lens type itself. Forinstance, see our P iris vs. auto vs. manual iris shootout.

The reality is that IP cameras today typically adjust the shutterspeed dynamically and automatically, allowing them to handle

http://ipvm.com/report/p-iris_lens_test




super strong sun light (fast shutter) to pitch darkness (slowshutter).

The key exception and the main benefit why photographer’s desireiris control is for optimizing the depth of field. However, depth offield is rarely a practical issue in surveillance.

If your camera supports P or auto iris, great. It might have somebenefit in some scenes. However, we do not recommend rejectingcameras with fixed or manual iris simply because of the iris choice.



Depth of Field Tutorial

Ignore depth of field concerns for 95%+ of surveillanceapplications, despite what you hear. While this is a commonconsideration in digital photography, its goals and logistics differ. Inthis note, we explain the drivers, why it is generally not asurveillance concern and the exceptional application where it isplus what can be done.

Photographers Often Prefer Shallow Fields of ViewPhotographers often want to emphasize a particular subject in thefield of view while essentially blurring out the background. To dothis, they reduce the depth of field. Take a look at the image below.A photographer would most likely prefer the one of the right if theywere showcasing the figurines:

However, in surveillance, it is the opposite. One almost alwayswants a very wide depth of field so that you do not lose details thatmight prove important for later investigations.


Drivers of Wide Depth of FieldThe closer a subject is to the front of the FoV the shallower thedepth of field will be. This can happen either because the subject isphysically quite close to the camera or a long lens used. Here's anexample from a YouTube tutorial when the subject is very close:

Notice at 3 foot, depth of field is poor but at 9 foot, it is muchbetter.

Now, here's an example where the subject is far away but the lensis long and the subject is the front of the FoV:

In Surveillance, Not a Common Issue95%+ of real world surveillance consists of:

https://www.youtube.com/watch?v=OUYuUs1aaCU




Wide angle shots (e.g., 3 - 8mm) With subjects 5 or more feet away from the camera

Because of this, shallow depth of field is simply not a common fieldproblem. Trying to deepen the FoV in these conditions will do littleto no good but can cause big problems in low light.

Calculate For YourselfDepth of Field size can be calculated mathematically. Here is anice Depth of Field calculator we recommend.

Below is a short 3 minute video showing you the drivers and thecalculator in action:

The Surveillance ExceptionThe most common, though still infrequent exception, is when asurveillance camera uses a long lens to observe far from thecamera. Below is an example looking down a 200 foot hallway.

http://www.dofmaster.com/dofjs.html


To eliminate the shallow depth of field above, increase the F-stop to reduce the iris opening.

However, two important conditions need to be met:

Use a manual iris lens to close down the iris and keep it fixedthere. An auto iris lens may automatically adjust the irisopening creating depth of field problems.

Ensure that you have lots of light 24/7 or whenever you wantimages. Closing down the iris will create terrible image qualitywith even moderate low light.




All in all, do not worry about depth of field but if you have a rarecase where it is an issue, think carefully about the tradeoffs andissues involved.


Lens Selection Recommendations

Selecting the right lens can be confusing and tough, especiallybecause lenses are often integrated into cameras, severelyrestricting flexibility to mix and match the right lens feature sets. Inthis tutorial, we examine 7 key criteria in selecting the appropriatelens. They are:

Lens Length / FoV Width Varifocal or Fixed Focal F-Stop Iris Type Shutter Speed Color vs. D/N Lenses Lens 'Resolution'

Lens Length / FoV WidthYou need to know what lens length you need, because thisdetermines how wide (or narrow) a Field of View (FoV) you can see.Do you want a 3mm, 8mm, 12mm, and 50mm lens? The longer thelens, the more narrow the FoV. See our lens length and tutorials for

details.

Typically in surveillance, 10mm or less is used because wide FoVsare most common. But there are many applications where oneneeds to see far away, requiring longer lenses. To determineexactly the lens length needed, use a lens calculator. For anexample of what you need to see miles away, see this super longlens discussion.



http://ipvm.com/forums/forums/video-surveillance/topics/view-a-person-s-face-3000-meters-away

http://ipvm.com/forums/forums/video-surveillance/topics/view-a-person-s-face-3000-meters-away


Varifocal or Fixed FocalLens length is either fixed or adjustable. For instance, the lens maybe 3mm with no other options (that's fixed) or adjustable between3mm - 10mm (that's varifocal). Overwhelmingly, surveillance usersprefer varifocal (see our survey results on varifocal vs. fixed formore). However, fixed focal lenses are less expensive and typicallyfound on lower cost cameras, so are often used to reduce costs.

If you use varifocal, you have more flexibility adjusting the FoV. Ifyou used fixed, the only choice to do the same is move the cameracloser or farther away from the subject.

F-StopF-Stop is a strong indicator and determiner of low lightperformance. The higher the F number, the less light the lens willpass and the more likely the camera will have problems in low light.For instance, an f/1.4 lens takes in a lot more light than a f/2.8 one(actually 4x). See our F-stop tutorial.

Always check the lens F-stop, especially if comparing different formfactors or wide price ranges, as the differences can be extreme andhave a huge practical impact

Iris Control TypeThe iris is the opening that allows light to pass through the lens andto the camera. The four common choices are fixed, manual, autoand P iris. While higher end cameras typically use auto or P iris, ourtesting does not show much benefits for iris choice. For more onthe differences between these controls, see our Iris tutorial.







Shutter SpeedThe shutter is NOT part of the lens but is related because itsignificantly impacts the sensor's exposure to light. Many camerasuse both iris and shutter speed control to regulate light input (seeour shutter speed vs. iris tutorial).

The shutter determines how long the sensor is exposed to light andis typically expressed in fractions of a second (1/1000s, 1/100s,1/30s, 1/3s, etc.). See our shutter speed tutorial for more.

One big issue to beware is slow shutter speeds. Manymanufacturers market this as a miracle technologically because, inreally dark scenes, it can make an image bright but it createsblurring and ghosting of moving objects. This is why we say thisfeature, called Sens Up, is for suckers.

Lens 'Resolution'While cameras are typically marketed by their resolution, i.e. pixelcount, like 1MP, 2MP, 3MP, etc., lenses are not. First, pixel counthas no direct meaning because there are no pixels in lenses. Pixelsare a part of image sensors, not lenses.

However, to make it simpler for users, lens manufacturerssometimes rate their lenses for resolution, such as 1.3MP or fullHD, etc. Technically, the more accurate term is line pairs /millimeter (lp/mm) or how many lines a lens can display in a givenarea, with the more the better. The problem is that lensmanufacturer rarely reveals this metric, making it useless asjudging criteria.







The best bet is to use the lens that the camera manufacturerrecommends. As long as your manufacturer is reputable, they willrecommend or require you to use a certain tested and verified lens.Using a cheap lens will not save much money but can causeproblems. The exception to this rule of thumb is if you have doneyour own comparative tests with the alternatives you haveconsidered. For instance, see our HD lens shootout.

Megapixel and Super Megapixel

Two rules of thumbs here:

Never use an SD lens on a megapixel camera. You will almostcertainly significantly degrade image quality.

For 3MP or less resolution, many quality lenses exist. Justmake sure they are rated for MP and the cameramanufacturer approves. Above 3MP, it is much more difficult.First, varifocal lenses are much rarer. Secondly, the lensestend to be significantly more expensive.

Color vs. Day/NightIf you are using a day/night camera with a mechanical cut filter, usean IR corrected (sometimes marketed Day/Night) lens. Otherwise,you may have a focus / blurriness issue at night. The good news isIR corrected lenses are common and do not cost much more.

FocusingEven if you have the right lens, you still need to make sure it is infocus. This is especially important since most use varifocal lensesthat require fine focusing after adjusting for the right lens lengthfor one's scene. Auto back focusing / auto focusing are increasingly

http://ipvm.com/report/hd_lens_shootout




common and help greatly with this. IP camera installationtools should be considered but it's tricky finding the right one asthere's no great, general solution (as there was with analogcameras). For more, see our focusing tutorial.





CAMERA SELECTION


IP Camera Form Factor Selection

When selecting a camera, you can choose from a number ofdifferent form factors and options. Each form factor comes with itsown unique strengths and weaknesses - both in terms of physicalsizing and advanced features provided. In this report, we examineeach form factor, providing recommendations on when to use eachtype.

At a high level, 5 form factor categories exist:

Cube Bullet Box Dome PTZ

Beyond those, 6 other fundamental options are especiallyimportant:

Vandal Housings Day/Night functionality WDR for PTZs: pan range, tilt range, optical zoom

These are not the only functionalities that count. There are over 40criteria that sophisticated users routinely consider. However, these11 are the 'big' ones that factors in almost every camera selectiondecision.


Cube CamerasCube cameras are generally the least expensive cameras and, assuch, are often deployed in residential or small businessapplications. A few IP cube cameras have an online price under$100 and the majority is under $250.

Here's a sample of what a cube camera looks like:

When considering cube cameras, a number of important limitationsshould be considered:

Fixed focal lenses: If you want to adjust the Field of View of acube camera, you will have to physically move the camerato accommodate

Not Day/Night: It is extremely rare for them to have amechanical cut filter, ensuring poor low light / night timequality

Rare IR support: Only a few cube cameras have integrated IRLEDs to enhance low light / night time imaging

WDR / Bright light issues: In our ongoing tests, cube camerasgenerally have moderate to severe problems in dealing withbacklight or lighting variances


Lack of PoE support: Less than 25% of cube cameras have PoEsupport

Indoor only: Very few are rated for outdoor use and those areonly IP54 rated against dust and water splashing

Short Warranties: More than 70% of cube cameras have a 1year warranty while other form factors regularly have 2 or 3year warranties

On the other hand, some cube cameras offer more advancedfeatures:

About half have integrated wireless networking; while thisusually works only over short distances, it can be helpful toeliminate network cabling. Also note that wireless support ismuch more common in cube cameras than any other formfactor.

Higher Frame Rate: More than 70% of cube cameras offer15fps or higher which is generally more than enough for mostapplications

Maximum resolution tends to be lower than other formfactors.

Finally, cube cameras are generally small providing a low profile(especially compared to box cameras). However, if aesthetics andconcealment are key, domes provide the best option.

We've tested a number of cube cameras. For more, read/watch ourreviews on Cisco/Linksys, D-Link, Lorex, Panasonic and TrendNet cube cameras.

http://ipvm.com/report/cisco_linksys_wvc80n_test

http://ipvm.com/report/dlink_ip_camera_dcs920_test

http://ipvm.com/report/dlink_ip_camera_dcs920_test

http://ipvm.com/report/lorex_ip_camera_lne1001_test

http://ipvm.com/report/panasonic_blc201a_camera_test

http://ipvm.com/report/testing_trendnets_internet_camera_server_tvip110


Box vs. Dome CamerasMost of the time, deciding on a fixed camera comes down to adecision of box vs. dome. Indeed, about 90% of fixed camerasmade and used are box or dome. By contrast cube and bullets are'specialist' form factors.

We are going to compare the tradeoffs between using box anddome form factors.

The chart below provides an overview of the tradeoffs:

Criteria Box Dome

Interchangeable Lens Very Common Uncommon

Aiming Flexibility Easy Can be Limited

Price Slightly Cheaper Slightly Costlier

Install Time Easier Indoors Easier Outdoors

Cutting Edge Features Sometimes More

Aesthetics / Concealment Weaker Stronger

Vandal Resistant Rare Common

Outdoor Ready Needs Enclosure Often Built-in

Integrated IR Rare Often

Box CamerasBox cameras provide flexibility and simplicity at a relatively lowprice. Let's examine the main reasons that users choose boxcameras:

Interchangeable Lenses: About 90% of box cameras allowusers to easily change lenses. This is important especially ifyou are trying to view something that is far away (and will


require a telephoto lens). By contrast, less than 33% of domecameras support interchangeable lenses and those that dousually have size constraints because of the tighter physicalenclosure.

Aiming Camera: If you need to aim a camera in any anglerather than straight ahead, box cameras tend to be easier andprovide greater range than dome cameras. With domecameras, because they are enclosed within housing,movement can be restricted (though this varies depending onthe design of the dome).

Lower price: Box cameras generally have a lower price, allthings being equal, compared to domes. For instance, theaverage SD box camera, without analytics, costs ~$550. Bycontrast, the average SD dome camera, without analytics,costs ~$625.

Less Time to Install: Because dome cameras are oftenattached by a short mount to a ceiling, they often can be setup quicker and with less skill. While providing superioraesthetics, domes can be more complicated to install.

More Cutting Edge Features: When features are new, theytend to appear first in box cameras rather than domes. Forinstance, the highest resolution cameras continue to be inboxes rather than domes. Also, more box cameras have builtin advanced video analytics than domes.

These noted, domes offer a broad array of advantages over box

cameras.


Dome CamerasWhile domes can be slightly more expensive, they offer a numberof physical options/advantages that are rare with box cameras.

Aesthetics/concealment: Domes can mount flush against aceiling or wall, making them relatively inconspicuous. Thatnoted, dome sizes vary significantly from mini domes to bigbulky domes. Mini domes offer the bestaesthetic/concealment abilities.

Vandal Resistant: Over 60% of domes are vandal resistantcompared to less than 10% of box cameras. If you areconcerned about people damaging your camera, vandalresistant is valuable. Note though that the amount or level ofvandal resistance of a particular camera can vary dramatically.While official vandal metrics exist (called IK ratings),manufacturers rarely disclose if or what results their camerasachieved.

Outdoor: If you want a camera that can be mounted outdoorswithout adding a separate housing, domes are preferable.More than half of dome cameras are outdoor rated whilefew box cameras are.

Integrated IR: If you want to improve low light / night timeperformance, some domes provided integrated (built-in) IRLEDs. This is a low cost way of improving video quality whenartificial lighting is not available. On the other hand, thedistance achievable can be short (less than 20 meters / 60feet) and the presence of IR LEDs so close to the imager cancause image problems.

http://en.wikipedia.org/wiki/EN_62262


Let's say you want vandal resistant, outdoor cameras withintegrated IR but prefer the box form factor for its ease of aimingand ability to interchange lenses.

Bullet CamerasBullet cameras can be best thought of as a specialist form of boxcamera. Bullets usually add a few features/benefits uncommon inbox cameras. Let's examine the common patterns:

Over 75% are IP66 or IP67 rated: This makes bullets easier todeploy outdoors as there is no need to buy and install aseparate enclosure.

Over 80% support true/day night: This makes bullets goodoutdoors in low light situations.

Over 80% of bullets have integrated IR illuminators: Thismakes bullets good when there is no light and you need to seeshort distances (usually 50 feet / 15 meters or less).

Below is an example of a bullet camera. Notice both the outdoorhousing and the built-in IR LEDs around the lens

PTZ CamerasWhen considering PTZs, the most basic decision is: PTZ or fixedcamera. Can you justify paying significantly more to get the


benefits of a camera that you can control across a wide area (i.e., aPTZ)?

We have 2 fundamental reports that examine the key issues inselecting PTZs. We recommend you read these first beforeselecting PTZs:

Training- PTZ Surveillance Basics: includes video clips thatshow PTZs in action, explaining the relative tradeoffs

Should You Use PTZ Cameras?: an examination of theadvantages and disadvantages of PTZs compared to fixed andmegapixel cameras

PTZ OptionsWhen selecting PTZs, 3 elements most uniquely impact pricing andperformance:

Optical Zoom: Choosing optical zoom is important when youneed to see things that are far away. In practice, Optical zoomranges from about 3x to 36x (with a few PTZs with lower andhigher zooms). While it's generally believed that the longerthe optical zoom, the farther the PTZ can 'see', this is notalways correct. The optical zoom measures the range of focus.For instance, if a PTZ has a 20x optical zoom, it means thatthere is a 20 times difference between the camera's widestand narrowest focal length (e.g., 4 mm to 80 mm). However,another camera with a 20x optical zoom can have a focallength range from 3.3 mm to 66 mm. Assuming the first PTZhas the same size imager, which PTZ will be able to see'farther'? In general, a higher optical zoom number means acamera will see farther but not always. Secondly, the

http://ipvm.com/report/training_ptz_surveillance_camera_basics

http://ipvm.com/report/should_you_use_ptz_cameras_surveillance


difference between an 18x optical zoom and 36x optical zoomdoes not mean you can see 18x as far. Assuming the camerashave the same minimum focal length (e.g., the 18x PTZ has arange - for example - of 3.5 mm to 63mm and the 36x PTZ hasa range of 3.5mm to 126 mm), the 36x PTZ may 'see' twice asfar (at most).

Pan Range: Pan Range measures the freedom the PTZ has tomove horizontally. The maximum range is 360 degrees,meaning that the PTZ can move horizontally continuously to'look' in any direction. About 60% of PTZs support 360 degreepanning. If you plan to have a PTZ in the middle of an area anddedicate operators to track suspects, you should stronglyconsider a PTZ with 360 degrees panning. This will cost, onaverage, a few hundred dollars more but will help ensure thatyou do not lose suspects due to constraints on panning thePTZ.

Tilt Range: Tilt range measures movement vertically (lookingup and down). The 'magic number' for tilt range is 180degrees. This means the camera can look all the way from oneside to the other (e.g., look to the right, look all the way down,look to the left). This is important, just like with 360 panning,to make sure you can track a suspect across a facility.However, only about 30% of PTZs can do 180 degrees or more(fyi - the maximum tilt range in our finder is 220 degrees). Notsurprisingly, these cameras are more expensive - expect topay about $150 - $300 more for this feature.

PTZ Pricing and Cost TradeoffsCentral to the PTZ decision is understanding pricing tradeoffs. PTZpricing ranges significantly (by 10x) and can be much moreexpensive than fixed cameras (often by 3x). While PTZs add an


important element, the extreme increase in price requires carefulconsideration.

Let's review key pricing tradeoffs:

Compared to fixed box cameras, PTZ cameras are about 2 to 3times as expensive. For instance, a box SD camera has anaverage cost of about $600 while an SD PTZ camera has anaverage cost of about $1500. This is somewhat offset by fixedcameras often not providing a lens and not being outdoorready. As such, the actual price increase can vary. However,for similar feature sets/resolution, expect to pay at least 2times the price for a PTZ (over a fixed camera).

Compared to a 5MP camera, indoor SD PTZ cameras are aboutthe same price while outdoor PTZ cameras are significantlycheaper. For instance, an average 5MP box camera costsabout $1200 - roughly the same as an indoor SD PTZ.However, a 5MP box camera is about $600-$700 less than anoutdoor SD PTZ camera.

Really basic PTZs can be quite cheap. For instance, over 25PTZs cost less than $750. However, the average pan range isabout 180 degrees and the average tilt range is about 90degrees. The average optical zoom range is 2-3x. Thissignificantly limits where and how far the PTZ can look.

Outdoor PTZ are far more expensive than indoors PTZs: onaverage, about $900. This is partially a consequence of havinglonger optical zooms (manufacturers reasonably assume thatPTZs outdoors will need to see farther).

General Camera OptionsLet's conclude with reviewing 3 other important camera options.

http://ipvm.com/camera-finder/results?search%5bform_factors%5d%5b%5d=1&search%5bresolutions%5d%5b%5d=6

http://ipvm.com/camera-finder/results?search%5bform_factors%5d%5b%5d=5&search%5bmax_online_price%5d=750

http://ipvm.com/camera-finder/results?search%5bform_factors%5d%5b%5d=5&search%5bmax_online_price%5d=750


Day/NightIf you have any scenarios where lighting may be poor, we stronglyrecommend you use cameras that support 'true' day/nightfunctionality. Even if the scene is just dim or weakly lighted,day/night support can make a big difference. While cameravendors routinely cite minimum illumination in the sub 1 lux range,visible camera quality begins to deteriorate seriously even at 5 - 10lux (which is relatively clear, if not bright, for human perception).To see this in action, take a look at the images in our low light vs.image quality test.

Make sure you choose a 'true' day/night functionality. This can bedone by using a mechanical cut filter (sometimes called an IR cutfilter) or by using dual imager (one color, one black & white). Dualimagers are rare but mechanical cut filters are commonplace andfairly cheap (only about $50 - $70 more than a 'color only' camera).Sometimes vendors say they have an 'electronic' day/night camera.In our testing, no 'electronic' day/night functionality can match thelow light improvements that a mechanical cut filter can deliver.

Equally important, we have found that day/night functionality isthe most important and significant predictor of good low lightperformance.

WDRWDR, or Wide Dynamic Range, is an important functionality forhandling lighting issues, most commonly strong direct sunlight(e.g., seeing the face of a person who is opening a door that facesoutside).

http://ipvm.com/report/how_lowering_light_levels_impact_quality



WDR is generally measured in dBs (decibels) with a range of 50dBto 120dB. Regular, non-WDR cameras usually have WDR ratings ofabout 60 dBs. By contrast, WDR cameras have rating of 100+ dB.However, many cameras (most notably Axis) do not list a decibelrating.

Worse, decibel ratings for WDR do not mean anything for realpractical use. While the scale is quantitatively meaningful andreproducible, it does not map well to real world use cases. WDRtests generally measure the degrees of gray that an imager canreproduce (e.g., 120 dB on Pixim's chart means a display of 20stops). (Read Pixim WDR measurement paper for a goodbackground on how one manufacturer tests and produces theirWDR ratings). The image below shows a result for Pixim's chip andthe different step levels it reproduces.

The problem with this approach is that it does not easily show norrelate to standard surveillance scenes (such as the aforementionedperson walking into a front door with heavy sunlight behind them).To test this, we use a lux meter and measure the actual lux levels.Here's a sample from the video testing of a Sony WDRcamera showing the lux measurement process:

http://dl.dropbox.com/u/3889140/pixim-dynamic-range-measurements.pdf

http://ipvm.com/report/testing_sonys_hd_camera_sncch140

http://ipvm.com/report/testing_sonys_hd_camera_sncch140


We took lux readings throughout to measure the specific variationof this scene. From the brightest point (outdoors - 2000 lux) to thedarkest (indoors on the left - 70 lux), there was nearly a 30xdifference in light. We found using this process to be reproducibleand much more relevant to real world surveillance performance.[Note: if you have not used a lux meter, you should; start byreviewing our lux meter training].

Three final notes of caution using WDR; while good WDR can makea big visual difference:

Lots of manufacturers claim to support WDR. There's nostandard or regulation behind this. So far, only Panasonic,Sony and Pixim WDR cameras demonstrated significant WDRenhancements (note: Pixim supplies chips to manymanufacturers).

WDR usually costs substantially more and tends to only beavailable on premium product tiers. For instance, only a fewSony and Panasonic cameras support their WDR functionality

http://ipvm.com/report/measuring_low_light_surveillance_with_a_lux_meter


and those tend to be hundreds of dollars more than theirregular IP cameras.

When WDR is on, low light performance usually suffersmodestly. In the cameras we tested, there's no way aroundthis (short of turning off WDR which would defeat thepurpose of buying a WDR camera in the first place).

Vandal HousingsThe value of vandal housing is protection against damage -primarily from humans. About 150 IP cameras claim to be vandalresistant. More than 90% of those cameras are PTZs or domes.Only a handful of other cameras (box, cube, etc.) are vandalresistant.

The big challenge with vandal resistance is the lack of clarity orvalidation on the degree of resistance. A standard does exist,however camera vendors rarely declare their ratings. Thesemeasurements are called IK ratings, measuring mechanical impactresistance. The maximum rating on the scale is IK10 which is testedby a 5.0 kg ball being dropped at a 40 cm distance. Here's a 5second video Sony shared with us showing the test in action:

A handful of the larger vendors (e.g., Axis, Sony, and Pelco) havetold us that some of their cameras are IK10. However, we rarelysee this declared on specification sheets.

Also, some vendors will specify their products as 'vandal' resistanteven if it is IK7, which requires 90% less force resistance than IK10.

If you are really concerned about vandal resistance, ask yourvendors specifically about the rating and testing performed.

http://ipvm.com/camera-finder/results?search%5bvandal%5d=1

http://en.wikipedia.org/wiki/IP_Code#Mechanical_impact_resistance

http://en.wikipedia.org/wiki/IP_Code#Mechanical_impact_resistance


Minidomes vs. Full Size Domes

Not too long ago, dome cameras were huge, fitting a full-size boxcamera into a large protective bubble. The move to "minidomes"changed that, cutting their size in half or smaller. Now, thedefinition of "mini" has changed again, with even smaller domesavailable, and manufacturers seemingly in a race to see who canbuild the world's smallest dome. In this note, we look at the prosand cons of full size domes vs. this new generation of minidomes,concluding with our recommendations on when to use each.

This image illustrates the difference in form factor between thesetwo types of dome:

Full Size Domes"Full size" dome cameras are generally 5-8" in overall diameter,with 3-4" domes. Cameras this size has been the most widelyavailable until the past few years, when even smaller domesbecame available. Due to this larger size, there are severaladvantages to full size domes:


Wider lens selection: Full size domes generally provide morelens options than smaller domes, in some cases using CS-mounts. Varifocal lenses are commonly available, an optionrarely found in minidomes.

More features available: Features are available in full sizedomes which are not often found in minidomes, such as trueday/night functionality, wide dynamic range, digital I/O, andaudio.

Lower F-stop: The larger form factor allows for bigger lensesthat can take in more light. While full size domes routinelyhave F numbers less than 1.6, minidomes often have Fnumber over 2.4 - a big difference in low light performance(see F-stop tutorial for more).

Outdoor ratings: Full size domes are generally available inIP66-rated outdoor versions, in some cases with heaters andblowers. Many minidomes are not outdoor-rated, or carrylesser IP ratings.

The main drawback to using full size domes is their size. For someusers, this may create aesthetic issues, as they prefer not to have alarge dome mounted on the ceiling. Recess kits are available, whichplace everything but the dome itself above the ceiling, but theseadd cost and require additional installation.

Full size domes vary widely in cost, depending on feature set. Basicdomes may cost $400 or less, with more advanced models withbetter low light and WDR performance over $1,000.



MinidomesSmaller than full size domes, minidomes typically are 3-4" indiameter, with 1-2" domes. They are a relatively recentdevelopment compared to larger domes, becoming widelyavailable in the past 1-2 years. Because of their size, they aregenerally considered to be more aesthetically pleasing, without theneed to recess the camera in the ceiling. They are also typicallyquicker to install, since they are, with a few exceptions, lightweightand intended for surface mounting, requiring less installation labor.

Because of this small size, however, there are some tradeoffs to beconsidered when using minidomes:

Limited lens selection: In most cases, minidomes are availableonly in fixed lens versions, typically wide views. In some cases,optional lenses (often M12 mount) may be used, but very fewvarifocal options are available. TheIQinVision Alliance-mini isone of few domes in this size available with varifocal lens.

Lack of advanced features: Minidomes typically sacrificefeatures such as true day/night, wide dynamic range, or I/O,due to their size. Most minidomes use electrical day/nightinstead of a mechanical cut filter, which provides lowerquality images at night.

Because of their smaller size and typically reduced functionality,minidomes generally cost much less than full size domes, in therange of $200-300 USD.

Which to ChooseMinidomes are far more frequently selected than full size domes,driven by lower cost and more preferable aesthetics. However,

http://www.iqeye.com/sites/default/files/Alliance-mini.pdf

http://www.linkedin.com/groupItem?view=&gid=1300007&type=member&item=170871258


sometimes advanced functionality only found in full size domes isneeded.

When deciding between these two, a key factor will be advancedimaging requirements - both for low light and WDR. Mostminidomes are color only, with poorer low light imaging comparedto a true day/night full size dome using a mechanical cut filter andlarger diameter lens. Likewise, minidomes typically do not includeWDR to keep cost low and size minimal.

Lens selection is likely the second deciding factor when choosingdome form factor. Since the majority of minidomes include fixedfocal length wide angle lenses, they may not be appropriate wherea narrower view of an area is needed. Full size domes may be moreappropriate in these cases, due to the wider lens selection, withsome manufacturers offering multiple models of these domes withdiffering varifocal ranges.

If these two issues are not a factor, the combination of improvedaesthetics and often far lower cost make minidomes a moreattractive option.


IP Camera Specification Guide

This report provides the most in-depth guidance on specifying IPcameras.

Specifying IP cameras correctly can be hard, as many factors impactperformance and 'best' practices are prone to major errors andmanufacturer manipulation.

Specifying ProblemsOur ongoing RFP reviews show a sad tale – copied RFPs,specifying older tech at extremely high costs, systems costing 20xmore than planned and systems underestimating needs and thenfailing.

The Big 3 IssuesWe find 3 patterns that we examine inside the Guide:

High level specifications where users think they are providingresponders freedom but make things worse

The Frankenstein specification that literally creates a monster The borrowed specification that unknowingly booby traps

themselves

The 5 Most Common Camera Specification ErrorsThen we examine the 5 most common specific errors, including:

Low light: confusing choices and tricks involved WDR: dealing with untrustworthy specs, real and fake WDR Resolution: how much is needed and why more can be worse







Using PPF without the ugly downsides Overcoming traps in storage duration

Finally, we provide recommendations and template for another 20common specifications:

Form Factor Frames Per Second CODEC Main Target of Camera Horizontal Field of View Distance from Camera Maximum Exposure Setting Integrated IR Audio Outdoor Rating Temperature Range Vandal Resistance Multi-Streaming Streaming Mode Recording Mode On Board Storage VMS Compatibility Power Supply Auto Focus Iris Type Lens Type PTZ Optical Zoom PTZ Pan Range PTZ Tilt Range Digital Zoom / Total Zoom


Panoramic vs. PTZs

Avoid High Level SpecsLots of specifications are vague, asking for something like "a highresolution low light IP camera." This type of specification almostalways leads to big problems. Many responders will immediatelypick the lowest cost model they have, in the belief that (1) therequester either does not know or care about specifics and (2) thatgiven this; low price will be the determining factor.

This most often happens when a requester is lazy or incompetent.While you do not need to specify every little element, make sureyou understand and include the 5, 10 or 20 that are mostimportant to you. That is the purpose of the rest of this guide.

Avoid Frankenstein SpecsIP cameras are not like PCs. You cannot go online and custom builda camera (e.g., I'll take 5MP resolution, 60fps, a 30x optical zoom,IP68 in a box form factor). Unfortunately, we see too manyspecifications that take this approach, resulting in a Frankenstein'monster' spec that is impossible to deliver (see examples A and B).

If you are not sure how widely your preferred combination is, ask acolleague or post it as a question in our discussion group. If you askfor something that does not exist, many responders will notrespond at all (suspecting that this is unreasonable) or you willwaste a lot of their time as they run around on a wild goose chasetrying to find something that comes close.

Avoid "Borrowed" Specs

http://ipvm.com/forums/forums/video-surveillance/topics/frankenstein-spec

http://ipvm.com/forums/forums/video-surveillance/topics/5mp-ptz-camera



It might seem like a time saver for a user to borrow a specificationfrom an integrator or distributor or manufacturer. However, youmust presume that spec will silently force you to only use theircameras. Essentially all vendor prepared A&E specifications willcome with manufacturer specific insertions that no othermanufacturer can meet.

Axis might put in Lightfinder or Panasonic would add SuperDynamic III. We have seen far too many people assume this is justan industry term, rather than a brand specific one.

Sometimes it is more subtle, with a weird low level listing or acombination of features that would knock out all competitors.Good integrators can spot this very quickly but often by the timethey see it, it is too late to change it.

Bottom line, you are much better off simply specifying the 5, 10, or20 elements that are most important to you than 'borrowing' abooby trapped specification.

Embrace Acceptance TestingMost specifications are technical only (e.g., must have widget A, Band C, or features X, Y and Z), often leading to disappointing realworld results. While the responder will rightfully argue, "Hey, Idelivered what you asked for", the requester's real needs may stillbe unmet.

The best way to overcome this is to include acceptance testingwhere you ensure that the camera can deliver the details you needin the areas and times that are most critical to you. The maindownside is this exposes more risk to the responder because now

http://www.axis.com/files/whitepaper/wp_lightfinder_43131_en_1105_lo.pdf

http://www.panasonic.com/business/products-surveillance-monitoring/why-panasonic-super-dynamic-3.asp

http://www.panasonic.com/business/products-surveillance-monitoring/why-panasonic-super-dynamic-3.asp


they need to meet a tougher standard. However, you canovercome that by properly describing what you want.

Even Better - Initial TestingTo avoid disappointment at the end, you can run essentially thesame tests before the installation is even started. There are anumber of low cost portable power / IP camera setups that allowstaking cameras under consideration to the exact spot one wants tomonitor, quickly and easily verifying that it delivers the details andimage quality you need.

Low Light OptionsThe universal 'standard' for low light, lux ratings, is completelyworthless. Here's the full. Suffice to say, specifying .0001 lux doesnot to get you strong low light performance. For every one camerathat is truly strong in low light, there are at least 2 others who justmade up their lux ratings (that's right, manufacturers gradethemselves) and will still meet that spec. Worse, high qualitymanufacturers tend to be more conservative so you will block themout by specifying too unrealistic a lux level.

If you want low light performance, use 0.5 lux as a way to reject theobviously poor performing cameras. But don't go much lower anddo not conclude that a .0001 lux camera is 10x better than a .001lux camera. The numbers suggest it, but it is just as common for the'10x worse' one to actually be better in low light.

Mechanical Cut FilterDo specify a mechanical cut filter if you want superior low lightperformance. This does not guarantee the best but like the 0.5 luxmark, will throw out obviously poor performers.

http://ipvm.com/report/portable_power_for_video_surveillance


Low Light Optimized CamerasThere are cameras that are clearly better than others in low light.For instance, from our tests, the Axis Lightfinder and the BoschStarlight cameras are among the best HD low light cameras.However, there is no specific feature or metric that one can citethat would describe it in a non-vendor specific way.

Alternative - Integrated IR CamerasCameras with built-in IR are becoming very common and are quiteuseful, especially for short range situations where black and whiteare acceptable (IR means b/w only at night). Consider specifyingthis. However, keep in mind:

Do NOT specify a minimum number of LEDs. Some vendorslike to tout having 12 or 24 IR LEDs, etc. However, 2 classes ofIR LEDs exist. Cheaper cameras use a higher number of'consumer' LEDs while more expensive ones tend to usefewer, higher strength 'professional' LEDs. They can deliversimilar performance depending on the configuration. IgnoreLED 'count'.

Do NOT specify IR range unless you REQUIRE it to be testedand proved on site. Manufacturers are notorious for overspecifying their camera's IR range (i.e.., it can see 100 feet or100 meters and then not being able to do even half that). Thisis the same type of problem as lux ratings.

Do specify adaptive IR illumination if you plan to use avarifocal lens or expect subjects to be close to the camera.This will help eliminate overexposure / blooming.

For more, see our IR Surveillance tutorial.

http://ipvm.com/report/bosch_starlight_test

http://ipvm.com/report/bosch_starlight_test



Maximum Exposure SettingP.S. - When specifying low light performance, the most commontrick is the maximum exposure setting. Vendors will routinely showimages or videos with still conditions that are amazingly brightunder extremely dark conditions. This is little more than a basicphotography trick that any camera can support. However, it comeswith a very problematic downside - objects that move even slightlylook very blurry and cannot be identified. [For more, review ourreport on how exposure impacts low light surveillance video].

While many vendors try to pass this off as advanced technology(called sens up in some models), it is a simple change to a commoncamera setting - often labeled maximum exposure or shutterspeed.

If you want to avoid blurry night time images, require the camerasbe set at 1/30s maximum exposure speed to avoid such tricks.

WDR Right and WrongDealing with bright light and lighting variances is a commonproblem in surveillance. WDR, or Wide Dynamic Range, is a featureset that aims to address this.

Do not specify in dBs, even though this is the most common waymanufacturers report WDR performance. It is just like lux ratings,manufacturer self-rate, so it is not guaranteed that a 110dB hasbetter WDR than a 60dB camera (which hypothetically, if theratings could be trusted, it should).




Do specify multi-exposure WDR, as this is 'true' WDR. Do notspecify 'electronic' or 'digital' WDR functions as these are fake, lowperformance alternatives. Also, do not allow a vendor to convinceyou that BLC is the same as WDR. It is not.

For more, see our WDR tutorial.

Selecting ResolutionFor background, see our resolution tutorial.

In 2013, if you are using IP cameras, you should almost certainly gowith 720p / 1.3MP or higher. While there is some older SD / VGA orSVGA cameras, higher resolution models are typically available atthe same price or only tens of dollars higher. Indeed, the oneaspect historically cited as an advantage (better low light) hasmostly been eliminated due to superior imaging (like AxisLightfinder or Bosch Starlight) or integrated IR (available fromalmost every manufacturer).

The question then becomes should you use 720p HD, 1080p orhigher. Here's our guidance:

1080p provides more usable details than 720p for FoVs widerthan 20 feet / 6 meters. If you have a wide FoV, 1080p canmake a practical difference. Otherwise, everything else istypically equal, decide on price (1080p is regularly ~$100more than 720p models).

3MP and 1080p cameras are usually one and the same (i.e., acamera marketed as 1080p HD often also supports 3MP). Themain benefit of 3MP over 1080p is the increased verticalcoverage (4:3 aspect ratio with ~500 more vertical pixels than





the 16:9 1080p). See our aspect ratio shootout for imagecomparisons.

The next step up is 5MP. While 5MP increase horizontal pixelsa modest ~25%, a number of significant drawbacks start toappear: lower frame rate (instead of 30fps, 12 - 15 is typical),no multi-exposure WDR, worse low light, limited vendorselection. 5MP is not 'bad' but it has a number of limitationsthat can make it worse than going for a 1080p camera.

There are a handful of cameras above 5MP, with 10MP beingthe next most common and then a scattering of other 'super'high resolution cameras. Like their 5MP counterparts, theysuffer from a number of drawbacks but are even moreextreme - much lower frame rate and much worse low lightperformance is common.

If you are not certain, 1080p is a safe bet overall. That said, analternative is to set PPF and let the responder pick the 'right'resolution.

Using PPFPPF, or Pixels Per Foot, has grown in popularity as a resolution'neutral' way to specify quality. It works great unless the scene issunny or low light or the compression levels are decreased. Inother words, it does not work that great overall.

In our extensive tests, assuming ideal well lit conditions, here arethe metrics we found and how they match up to image quality:

Difficult to detect person: < 8 pixels per foot Rough guess of person (age, gender): 5 - 12 pixels per foot

http://ipvm.com/report/aspect_ratio_surveillance



http://ipvm.com/report/pixels_surveillance_video_test


Higher probability guess of person (hair, accessories, etc.): 15- 24 pixels per foot

Blurry face (could identify if you already knew the person): 25- 50 pixels per foot

Clear face (could identify a stranger): 50 - 80 pixels per foot Like TV quality (very sharp details of face and body): 80+

pixels per foot)

Review our detailed reference chart for sample images at each

pixels per foot range. Pick a number that matches the level of

quality needed. For more, see our PPF Guide.

PPF is good for estimating how many cameras you need but if youspecify a set PPF, you assume the risk / downside if the cameradoes not deliver in sunny or dark scenes (i.e., the responder can say"But you asked for 50ppf and I delivered it, the quality might bepoor but the pixel density is there").

Another big problem with PPF is that it is specified in isolation ("theparking lot camera must be 50pff"). It also requires preciselydefining the main target of the camera and the horizontal field ofview.

Main Target of CameraDefining the main viewing target of a camera is both good securitypolicy and advantageous to camera selection. The main viewingtarget is the most important area that a camera is 'looking at'. Asan example, a camera might be covering the front entrance. Themain target would likely be the doorway.

http://ipvm.com/test-results/pixel-per-foot-quality-table-IPVM-premium.pdf



Picking a main target is important because cameras cannot providethe same level of detail at different depths within an image. Allcameras 'quality' or image detail will decline as a target is furtherfrom the camera. An object 20 feet from a camera will look 'better'than an object 50 feet from the camera - regardless of the cameratype. For example, if you just barely get enough detail to capture aface clearly at 20 feet from the camera, it will be impossible to seea face clearly from that same camera at 50 feet away. You will likelydo no better than get a fuzzy outline of the person.

Finally, by defining a main target, the integrator can do a better jobof optimizing and ensuring that they meet the security needs.

Horizontal Field of ViewPixels per foot metrics are indefinite without defining thehorizontal field of view (FoV) to cover. The specifier must do this upfront to ensure that the appropriate level of detail is provided. Forexample, a user decides on 50 pixels per foot to deliver clearimages of a person's facial details. However, the user does notspecify how wide a Field of View this quality level needs to cover. Adesigner could assume that a 10 foot wide FoV is sufficient whenyou want this to be captured across a 20 foot wide FoV to capturepeople across an entire lobby. Assuming a 10 foot wide FoV, an SDcamera is sufficient. Assuming a 20 foot wide FoV, a megapixelcamera is necessary. The designer may specify an SD camera andthe installer may set it up to cover a 10 foot wide FoV. However,when the user asks for the camera FoV to be increased to 20 footwide, the image detail is lacking. The end result is an unhappy userand a dispute about whether the specification was met.


Bottom line, whenever specifying pixels per foot, specify thehorizontal FoV width to be covered. This is obviously more up frontwork but if this is not done, the risk of disagreement anddissatisfaction is high.

By defining the main target, the pixels per foot desired at thattarget and the horizontal FoV width of that target, specifiersmaximize the probability of video that meets their needs.

Storage Duration TrapsPretty much everyone specifies the storage duration (e.g., 2 weeks,30 days, 3 months, etc.). However, a major limitation is whatthe quality / compression level will be. Many assume that if theyspecify the resolution (e.g., must be 720p or 3MP) that is sufficient.However, that just defines how many pixels will be captured /recorded. It does not guarantee the quality of those pixels. Even ifyou have 10MP, if you set the quality / compression levels lowenough, it can look like VGA.

To hit storage duration targets, responders can simply and silentlylower the quality / compression levels because it can lower storageconsumption by 10 or 20% easily, allowing them to hit the storageduration target with less equipment. Unfortunately, this will screwup PPF calculations and reduce details for objects in wider FoVs.Worse, manufacturers use incomparable metrics (some label itlow/medium/high, others use a scale of 1 - 100, etc.), so it is noteasy to know

Minimally, require storage at the manufacturer defaultcompression / quality level. This will stop the most common trick.However, some manufacturers default to very low quality levels



and some default to high ones. If you are more technical, you canmeasure these levels across manufacturers by streaming video toVLC and using an open source measurement tool (see our tutorialof how to measure video quality / compression levels). If you do,we recommend a DRF / Quantization level of 27 - 30.

Other General Camera RequirementsThe rest of the guide details common but less tricky elements ofspecifying cameras.

Form FactorSpecifying a form factor is generally necessary only if you areconcerned about (1) aesthetics or (2) cost. Otherwise, the otherfunctional specifications will naturally impact the type of camera toselect.

Among fixed cameras, the fundamental form factor options arebox, bullet, cube and dome.

Most people who care about aesthetics (i.e., minimizing theobtrusiveness of a camera) prefer domes. Specifically, users whowant to make the camera as inconspicuous as possible prefer mini-domes. If this is an important factor for your use case, you shouldrequire domes or mini-domes (though understand the tradeoffsbetween the two).

Most people who want the cheapest solution possible prefer cubecameras. If you want to maximize the likelihood of the lowestpriced cameras possible require cube cameras. However, somepeople really dislike the look of cube cameras (often they look





clunky and 'cheap'). If you want to avoid this, specifically excludecube cameras in the requirement.

For an in-depth review of form factor options, see our Form Factorreview in our camera selection guide.

Frames Per SecondSpecifying the camera's frame rate is almost always included. Theonly practical question is what frame rate to select. This is a pointof great practical contention with two major camps - the 'goodenoughs' and the 'pursits'.

The 'good enoughs' argue that surveillance video does not need tolook like a movie to solve incidents. Almost no practical action ismissed in between frames even at 5fps. Users are better off at alow frame rate that meet security purposes needs and savessignificant storage expenses (higher frame rate, more storage - notlinear but close).

The 'purists' argue that surveillance video should be full frame rateto ensure that nothing is missed. They also argue that the cost ofstorage continues to decline so the price premium should not besignificant.

From a practical perspective, a few drivers should impact decisionon frame rate:

Legal or statutory requirements - if those exist, obviouslyfollowing them is important

http://ipvm.com/report/ip_camera_types_form_factors_training

http://ipvm.com/report/ip_camera_types_form_factors_training


Monitoring fast moving actions - money changing, cardgames, fast moving people - generally justifies at least 15 ifnot 30 fps

Personal / aesthetic preferences - some users just do not likethe stuttering look of video under 15fps

If none of those drivers impact a scenario, 5 - 10 fps should be fine.

Finally, keep in mind that multi megapixel cameras often do notsupport 30 fps - some of these cameras only support 5 - 12 fps.

Review our Frame Rate Training report to see the qualitydifferences in various frame rate settings. Review our frame ratereal world statistics to see what others typically choose. If you wantto see what 60fps delivers, see our 30fps vs. 60fps shootout.

CODECSpecifying the CODEC an IP camera should use is probably one ofthe easiest attributes to determine. Industry consensus hasemerged over the last few years around H.264. Theoverwhelmingly majority of cameras introduced since 2009 supportH.264 and now basically every VMS supports H.264. The corereason why H.264 is preferred is for bandwidth and storageefficiency.

However, specifiers should carefully consider if they should onlyrequire H.264 or allow other CODECs to be used. Here arerecommendations on other CODECs to consider:

MPEG-4 is essentially the previous generation of H.264. Theyhave similar designs with the main user difference is that

http://ipvm.com/report/training_frame_rates_for_ip_cameras



http://ipvm.com/report/testing_60_fps



H.264 has roughly 20% - 40% lower bit rate for the samesettings. Many cameras still support MPEG-4 including a largenumber released a few years ago who support MPEG-4 butnot H.264. To maximize the cameras to choose from, allowMPEG-4 to be used. The increase in storage costs is modestand some MPEG-4 only cameras are fairly inexpensive.

MJPEG is the most 'traditional' CODEC in video surveillancebut is the least bandwidth efficient of those commonly used inthe industry. While almost all new megapixel cameras supportH.264, MJPEG only releases were common up until 2009. Assuch, many megapixel cameras on the market only supportMJPEG. The bandwidth/storage penalty is quite severe. 5x to10x more than H.264 is fairly common. In general, werecommend excluding cameras that are MJPEG only.

MxPEG is a proprietary CODEC from Mobotix that has roughlysimilar performance to MPEG-4. For megapixel video, Mobotixonly supports MxPEG and MJPEG. To consider Mobotix, allowuse of one of these 2 CODECs.

JPEG2000 is a standards based CODEC but only used byAvigilon (among mainstream IP camera manufacturers).Avigilon's JPEG2000 cameras only work with their own VMSsystem. To consider Avigilon, allow for JPEG2000, thoughrecognize the potential for massive storage cost increase).

Most likely you will specify H.264. However, multiple levels /profiles of H.264 exist, including Baseline, Main and High profiles.The tradeoff is lower bit rate usage (for a given quality level) athigher processing power. We recommend you allow all levels /profiles and do not require a specific one. While there can bemodest bandwidth savings, so many other factors impact


http://ipvm.com/report/calculate_storage_surveillance


bandwidth consumption that it is not prudent to block out camerassimply because of the H.264 profile / level they use.

http://ipvm.com/report/calculate_storage_surveillance


Distance from the CameraDistance from the camera is generally overlooked in cameraspecifications. However, it is important in determining the lenslength used and often indirectly the type of camera.

If the target is within 5 - 15 feet of the camera, most cameras willbe able to meet this specification. However, when the target isfarther away, a special lens may be needed. For instance, a usermounts a camera on a wall and wants to see facial details clearly atan entrance over 50 feet away. Almost, no stock lens provided withcameras will cover this distance. Worse, some camera types, suchas some domes, cannot physically fit the larger lenses that arerequired for this distance. Whenever possible, estimate thedistance from the camera to the main target / viewing area for thecamera and include it in the specification.

We recognize that this can be challenging since estimating thedistance from the camera to the main target assumes knowledge ofthe camera’s positioning. The exact camera positioning may nothave been determined at this stage. However, if you believe that acamera will be mounted for away from its target, it is very useful tonote this up front so that the appropriate product can be selected.

Lens TypeNormally users do not need to specify details of lens. However, twoelements of lens specification are important: (1) the length of thelens and (2) the adjustability of the lens.

As alluded to in the preceding review of camera distance, thefurther a desired object is from the camera, the longer the lens




required. However, usually specifying an exact length is notnecessary. This is because varifocal lenses are common.

Systems can choose from fixed focal length lenses or varifocallength lenses. Fixed focal length lenses support only a single lengthlens and cannot be adjusted (e.g., a 6mm lens). Varifocal lengthlenses support a range of lens lengths and can be adjusted in thefield. Varifocal lenses are generally preferred because they providefield flexibility and allow a customer to direct adjustments to theFoV on site to get the exact right view for their needs.

If this flexibility is required, varifocal lenses should be specified.Otherwise, cameras with built in fixed focal lens may be providedthat are moderately cheaper.

Iris TypeThe other aspect of lenses that is a common option is defining howthe opening for capturing light is controlled (i.e., the iris). Threecommon iris types exist: Manual iris, Auto iris and P Iris. Withmanual, an installer sets the iris size once and locks it in. With auto,the camera can automatically vary the size of the iris on demand. PIris is similar to auto iris but provides finer grain control.

In our testing, differences in performance between the three arefairly minimal (e.g., see our comparative Iris results). As such, werecommend that for most cases, users specify any iris type. Note, ifP Iris is specified, camera choices are limited.

Auto FocusMost surveillance cameras need to be manually focused. Generally,this happens during initial installation / setup. However, a risk does

http://ipvm.com/report/p-iris_lens_test


exist that a camera will come out of focus and look 'soft' or blurry.The most common way this happens is by the camera beingphysically bumped or nudged. Some vendors claim that this canalso happen from changes in temperature or cutting over betweenday and night mode. However, we have not seen that nor have weheard this as a major issue for integrators.

The other relevant aspect of focusing is that it can be difficult tooptimize focus. When done manually, this requires a patient,steady hand especially with network video where latency can makefine focusing difficult.

For an extensive debate on the pros and cons of using auto focus,review our auto back focus preference statistics.

More and more cameras are offering built in auto focusingcapabilities that allow a push of a button (on the camera or from aweb interface) to focus the camera. The benefit is reducing installerfocusing error and eliminating future service trips to manuallyfocus a camera.

Two modes of automatic focusing exist: auto focus and auto backfocus. The utility is the same but the means are different. Withauto focus, the position of the lens change. With auto back focus,the position of the lens stays fixed while the position of the imagerchanges.

If this capability is desired and a modest premium (perhaps anadditional $100) is acceptable, require automatic focusing. Werecommend allowing both auto focus or auto back focus as theyprovide the same fundamental functionality.



AudioWhen specifying audio, we recommend factoring 3 issues:

The type of audio desired: Manufacturers offer 4 types ofaudio: microphone only, speaker only, half-duplex and fullduplex (half duplex is like a walkie talkie, full duplex is like atelephone). Do not simply specify audio. Specify the specifictype of audio needed for the application.

Whether audio is really needed: Audio is very rarely used.Most industry people cite usage rates of under 5%. Requiringaudio eliminates many of the less expensive. In the last fewyears, an increasing trend has been to only include audio inpremium tier camera offerings.

Whether audio is legally allowed: Many countries and regionshave strict regulations or restrictions against using audiosurveillance. Even in the US where lax regulations onsurveillance is common, 12 states essentially prohibit audiosurveillance as both parties (i.e., the company doing thesurveillance and the person on the premises) need to provideconsent (not practical in most surveillance applications). Seemore on audio surveillance legality and consent issues.

Outdoor RatingMost specifications will note if a camera is to be used indoors oroutdoors. However, often the specification simply requires thecamera to be for outdoor use. We strongly recommend all outdoorspecifications to list both an Ingress Protection (IP rating) and atemperature range.

http://en.wikipedia.org/wiki/Telephone_recording_laws#Two-party_notification_states


The reason for an IP rating is that some ambiguity exists over towhat exactly makes or defines a camera as suitable for outdoor.For instance, some vendors will mark their cameras as 'outdoors'even through the IP rating is only 52 or 54. By contrast, mostindustry professionals agree that the appropriate minimum foroutdoor use is IP66 (IP67 and IP68 are also available). By specifyinga specific minimum IP rating, the user ensures more exactperformance.

For background, review the IP codes. As a quick overview, the firstdigital refers to protection against solids and the second digitagainst liquids. For instance, the difference between rating in the50s and 60s is that 50s is only dust protected while the 60s is dusttight. Finally, the second digit, for liquids, identifies how muchwater the camera can withstand. An IP52 rating only coversdripping water while an IP67 rating covers immersion in water upto 1 meter.

Temperature RangeAlong with an IP rating, defining a temperature range is importantfor outdoor cameras. The average IP camera is only rated for atemperature range of 0 to 40 degrees Celsius (32 F to 104 F). This isfine if the camera is in a climate controlled indoor environment.However, if cameras are installed outdoors or in areas not climatecontrolled (e.g., a warehouse), it is important to specifically requirea maximum and/or minimum operating temperature.

We recommend starting with a check on minimum and maximumyearly temperatures in your area. Also, factor in that certain areascan get even hotter than the outdoor air temperature (e.g., a

http://en.wikipedia.org/wiki/IP_Code


warehouse). Use these temperatures as a baseline for setting yourtemperature range specifications.

VandalMany users are concerned about cameras being damaged throughphysical force (e.g., hitting or striking a camera with an object). Thecommon term used in the surveillance industry for cameras thatcan withstand some level of attack is 'vandal' or 'vandal resistant.'Only subsets of cameras are vandal resistant and those camerastend to be moderately more expensive. If a use case calls for suchprotection, require it explicitly.

To better specify the level of vandal resistance, consider specifyingthe requirement using an IK rating: "an international numericclassification for the degrees of protection provided by enclosuresfor electrical equipment against external mechanical impacts." AnIK10 rating is considered to be strong and is supported by a numberof camera vendors.

Multi-StreamingNormally, a single video stream is sent from an IP camera to a VMSsystem. However, some advanced VMS systems can supportmultiple video streams from a single camera to a VMS. This is oftenused when an organization wants to view live video at differentquality levels than recorded video or when server side videoanalytics are deployed.

Most, but not all cameras support multi-streaming. Also, manycameras support multiple streams but only at reduced bit rates(e.g., a 1.3MP camera may support 2 streams but only 1 at 1.3MPand the other at VGA).

http://en.wikipedia.org/wiki/EN_62262


If the application plans to use multi-streaming, call this out in thespecification. If the scenario calls for multiple high frame rate, highresolution streams, require this explicitly.

For more, see our multi-streaming guide.

Streaming ModeThe two fundamental choices for streaming mode are variable bitrate (VBR) and constant bit rate (CBR). This is rarely specified butcan become an important element in system design. Constant bitrate streams are generally preferred in low or unreliable bandwidthenvironments (e.g. wireless) while variable bit rate streams offerthe best overall storage efficiency.

Some cameras only support one of these two streaming modes soif this matters to the application, specify it up front so that laterproblems are avoided. For more on the tradeoff between VBR andCBR, see our extensive analysis in our H.264 / MJPEG codec report.

Recording ModeThe two most common / fundamental recording modes arecontinuous and motion based recording. Most organizationschoose one of these options for all cameras or for specific groupsof cameras (i.e., motion based recording for non-critical areas,continuous based recording for critical ones).

This specification is not likely to impact camera selection but willimpact storage utilization (total storage needed) and sometimesVMS section (a few VMS systems do not support server side motiondetection). For motion based recording, storage utilization will be

http://ipvm.com/report/vms_multistreaming_comparison

http://ipvm.com/report/h264_mjpeg_bandwidth_quality_test


based on the level of motion detected for each camera. This is veryhard to predict as it depends not only on the traffic in the scene(people, cars) but also lighting changes, video noise, shadows, etc.We believe this is too difficult and time consuming to specifyprecisely up front.

A third option is 'boost' or 'speed-up' recording which combinesthe two - continuous recording at a low quality level when nomotion is detected, switching to a higher quality when motionevents occur. This is ideal but make sure your VMS supports it.

See our recording mode statistics for comments on the tradeoffhere.

On Board StorageRecording inside the camera is growing in popularity. This can bedone as an alternative to traditional centralized recording or forredundancy (in case the network or VMS/NVR goes offline.

First, keep in mind that many IP cameras do not support on-boardstorage and some manufacturers only support this on premium tiermodels.

There are 2 traditional hardware specifications that you want toavoid:

SDHC vs. SDXC: the main difference is the maximum amountof storage supported, with SDHC maxing out at 32GB. Insteadof specifying this, just list the minimum storage size needed(16, 32, 64GB, etc.)



Form factors: Includes 'original', mini and micro. Cameras willdiffer in the form factor they support. However, this istypically not critical for the user specifying and limiting to oneform factor can inadvertently bar an otherwise useful camera.

The main specification should be SD card storage size, because it isthe most limiting factor. First, many, if not most, IP cameras areSDHC, topping out at 32GB (the equivalent of a 500GB 16 channelDVR - tiny storage for today's standards). Second, 128GB is as highas one can practically go today (equivalent of a 2TB 16 channel DVR- decent) but costs ~$100 per card (expensive).

VMS SupportRegardless of camera SD card support, VMS software support isequally important. Many IP camera manufacturer only support webinterface access of individual files or, worse, physically retrievingthe card. Make sure the VMS you plan to use will integrate with thespecific model you want. Most VMSes do not support SD cardrecording and those that do only support a handful of IP cameras.Plus, for those few that do, some support dedicated edgerecording, others redundant recording and one or two supportboth.

For more, see our SD card storage tutorial and edge storage /recording tutorial.

SD Card TypeSD card quality ranges from giveaways at trade shows, no namebrands at convenience stores to professional offerings. In our tests,cheap SD cards created a lot of problems (and others havereported similar problems). As such, given the modest premium

http://en.wikipedia.org/wiki/File:SD_Cards.svg





between no-name and brand cards, we recommend specifying onlya professional one - SanDisk or similar.

VMS CompatibilityThis depends if you have already selected or have a VMS. If you do,simply reference the VMS and the current version you are running(especially if your version is out of date) as this can restrict cameracompatibility.

If the VMS is to be determined, this becomes tricky as VMSversions differ. Our discussion on how to define openarchitecture should help. Specifying ONVIF Profile S officialconformance is probably the most open, and by far widelysupported option. However, while 1500+ cameras support it, some(especially older ones) do not, including those that are directlysupported by many VMSes.

Note: Avoid specifying PSIA as it never reached a critical mass ofcamera / VMS vendors and is limited to a handful of vendors.

Power SupplyThe two most common options for power supplies for IP camerasare PoE and low voltage power. Generally, PoE is preferred for IPcameras. However, some use cases make low voltage powernecessary or strongly preferable.

When specifying PoE only, keep in mind that some older,inexpensive cameras support low voltage power only. By contrast,when specifying low voltage power, keep in mind that many newer,inexpensive cameras now only support PoE. This may soundstrange, but the trend flipped in the last few years.

http://ipvm.com/forums/forums/video-surveillance/topics/how-to-define-open-architecture-in-an-rfp

http://ipvm.com/forums/forums/video-surveillance/topics/how-to-define-open-architecture-in-an-rfp

http://www.onvif.org/ConformantProducts/ProfileS.aspx



High power PoE (HPoE) is also an option. This is generally used withIP cameras that consume large amounts of power, most commonlyPTZ cameras. If you are specifying a PTZ camera, you may want toallow for HPoE to not eliminate those cameras.

For more on selecting power, review our training report onpowering video surveillance.

PTZ Optical ZoomThe most common way to specify how far a PTZ can see is to selectan optical zoom range. Generally, this provides a good proxy formaximum distance though it suffers from 2 major limitations -variances in maximum focal lengths and differences in resolution.

In practical terms, optical zoom of commercially available IP PTZsgenerally range from 3x to 40x. These can be segmented into 3rough groups:

Under 12x optical zoom: These are usually quite inexpensivePTZ cameras designed for infrequent controlling

Between 12x and 22x optical zoom: These are mid-range PTZcameras generally designed for professional use in smaller,typically indoor areas

Over 22x optical zoom: These are generally the mostexpensive cameras designed for outdoor, long range use.

If a user wants a PTZ that can see as far as possible, it is betterspecify a maximum focal length rather than an optical zoom. Bydefinition, optical zoom is comprised of a minimum and amaximum focal length. For example, a 36x optical zoom camera

http://ipvm.com/report/powering_video_surveillance

http://ipvm.com/report/powering_video_surveillance


might have a minimum focal length of 3.5mm and a maximum of126mm (36x greater than the minimum). However, another PTZmight have the same optical zoom range but a higher minimumand maximum focal length (e.g., 4mm to 144mm). This second PTZ,all other things equal, would be able to 'see' farther.

Secondly, optical zoom ranges can only be compared directly forcameras with the same resolution. Increases in resolution providesimilar benefits to increases in optical zoom as they both effectivelyallow users to see farther. Equally importantly, the optical zoomrange of megapixel PTZs is always less than the maximum of SDPTZs. A PTZ with lower optical zoom range but higher resolutioncan see actually see farther (HD vs. SD PTZ test).

For more on how to calculate maximum distance seen with a PTZ,review our explanation of "How Far Can a PTZ See?".

IGNORE Digital Zoom / Total ZoomThe only zoom that really counts for differentiating cameras isoptical zoom. Unfortunately, many manufacturers conflate digitaland optical zoom. For instance, a manufacturer might say a camerahas a 216x zoom made up of 18x optical and 12x digital (i.e., 18 x12 = 216). Only focus on the optical aspect. Digital zoom is roughlythe same for all cameras and only 'enlarges' what was alreadycaptured.

For more, see our digital zoom tutorial.

PTZ Pan RangePan range defines how far horizontally (left to right) a PTZ cameracan move. The movement is circular and the possibilities range

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from 0 to 360 degrees. 360 is an especially important level for PTZpan range. With 360 pan range, the PTZ can move continuously totrack a subject. Anything else and the operator need to manuallymove the camera back the other way to track a suspect around anarea. A significant difference exists in price between PTZs thatsupport pan ranges of 350 and those that support 360. If anapplication will be actively monitored by a guard, we recommendrequiring 360 degree PTZ pan ranges.

Finally, many cheap PTZs have pan ranges of 90 degrees of lessproviding limited controllability. This is fine for applications wherethe user just wants to move the camera slightly to the left andright.

PTZ Tilt RangeTilt range defines how far vertically (up and down) a PTZ cameracan move. The practical range offered is from 0 to 220 degrees.This attribute is commonly not specified but is important forprofessional monitoring applications. The key decision to make iswhether the application requires a PTZ that tilts less than or morethan 180 degrees. If a PTZ tilts less than 180 degrees, an operatorwill need to awkwardly reposition the camera when a subject walksunderneath a camera (because the PTZ cannot rotate to the otherside).

If an application calls for a live monitor who will need to tracksuspects moving underneath the camera, we recommendspecifying a minimum of 180 degrees tilt range.


PanoramicsPanoramics are a fast growing alternative to both PTZs and multiplefixed, telephoto cameras. See our PTZs vs. 360 / Panoramicsguide for in-depth coverage.

III. Camera Specification FormThe following section provides a summary of each requirement andcommon options to consider. We recommend you copy and pastethis into your own documents and use it as a starting point indefining the requirements for your cameras.

Form Factor: Choices - Box, Bullet, Cube, Dome, Mini-Dome or PTZ

Compression Level: Manufacturer Default (to avoid gaming) or,advanced, a quantization / DRF level of 27 - 30

Resolution: Common choices - 4CIF/VGA (list both together as theyare very similar for surveillance purposes), SVGA (moderatelyhigher than VGA but not megapixel), 720p, 1.3MP, 1080p, 2.1MP,3MP, 5MP, 10MP. Specifying higher than 10MP will almostcertainly lock in a single or just a few vendors. [Note: can beomitted if pixels per foot and horizontal field of view is specified]

As an alternative to resolution, define the main target, pixels perfoot and horizontal field of view:

Main Target of Camera: Name a single point where each specificcamera should focus on, e.g., Camera 2 should focus on individualsentering the main double doors in Building B

http://ipvm.com/report/ptzs_vs_panoramics

http://ipvm.com/report/ptzs_vs_panoramics


Pixels Per Foot: Choices - anywhere from 10 ppf to 100 ppf: use10ppf if you just want outlines of people and cars, use 50ppf if youwant to see details of face / license plates; go even higher if youwant a higher margin of error / more robustness to environmental/ lighting issues

Horizontal Field of View: Choices - any width you want but must bespecified with a pixels per foot metric - critical to definingresolution; common reference widths - double doorway ~6 feet,two lanes road ~ 25 feet

Distance from Camera: Choices - generally 5 - 50 feet; this is anoptional specification; however, if provided helps integrator choosethe correct lens length

Low Light: Choices- mechanical cut filter or color only; if you havepoor lighting at night and need to see, require mechanical cut filter

Maximum Exposure Setting: Common Choices - 1s to 1/10,000;Recommendations - 1/30s to minimize motion blur at night; up to1s if you are OK with significant motion blur but want a brightimage

Bright Light: Choices: multi-exposure WDR or none; do not specifyelectronic or digital WDR as they are common and not much betterthan no specification here

Frames Per Second: Choices- typically 1 - 30; atypical up to 60;Recommendations - if you do not have regulations or legalrequirements, most surveillance video is fine with 5 - 15 fps


Audio: Choices: None, Microphone Only, Speaker Only, Full-Duplex,Half-Duplex; Recommendations - if you want audio, best to choosefull duplex; also verify compatibility with VMS and legalrequirements

Integrated IR - Choices: Integrated IR or no Integrated IR

Outdoor Rating - Choices: IP65, IP66, IP67 - if you really want touse a camera outdoor make sure to use an IP rating; can list it asIPXX or higher (e.g., IP65 or higher)

Temperature Range - Choices: Min as low as , Max as high as

Vandal - Choices: Vandal or not Vandal; Optional - IK Ratings tospecify the degree of vandal protection - most common is IK10

CODEC: Common Choices: H.264, MPEG-4, MJPEG; Recommended- H.264 and MPEG-4

Multi-Streaming: Common Choices: Single Stream or Dual Stream;Optional - dual streams at specific resolution and frame rates

Streaming Mode: Common Choices: Constant Bit Rate, Variable BitRate or either

Recording Mode: Common Choices: Continuous Recording, MotionBased Recording, Boost / Speed-up Recording

On Board Storage Size (Minimum): 32GB, 64GB, 128GB (Remember- verify VMS support); Optional - SD Card brand / manufacturer -SanDisk


VMS Compatibility: Choices - Name of Specific VMS Vendor, ONVIFor PSIA; Recommended - if a VMS is already deployed or selected,list the name of the specific VMS vendor; Do not specify PSIA

Power Supply: Choices: PoE, Low Voltage or both; Note requiringlow voltage will eliminate many newer cameras that are going PoEonly

Auto Focusing: Choices: Auto Back Focus, Auto Focus or neither;Recommended - if you want auto focusing list both auto focusingoptions but remember this will significantly limit camera options

Iris Type: Choices: Manual Iris, Auto Iris, P-Iris or Any;Recommended - use any as the cost variances are not significant;beware of choosing P-Iris as very few vendors support it today andthe benefits seem modest at best

Lens Type: Choices: Fixed Focal Lens or Varifocal Lens; Optional -specify lens length for fixed or lens range for varifocal;Recommended - if you want to precisely set up field of view,choose varifocal lens; 4 - 9mm varifocal for regions close tocamera; 10 - 50mm varifocal for regions farther from camera

The remaining choices are applicable to PTZ cameras only:

PTZ Optical Zoom: Common Range: 2x to 40x, specify as minimum;Recommendations - indoor/small areas 10x or higher,outdoor/large area 25x or higher [NOTE: these ranges are onlyapplicable to SD PTZ cameras]


PTZ Pan Range: Common Range: 30 degrees to 360 degrees,specify as minimum; Recommendation - live monitoring/ frequentguard use: 360 degrees

PTZ Tilt Range: Common Range: 30 degrees to 220 degrees, specifyas minimum; Recommendation - live monitoring / frequent guarduse: 180 degrees or higher

[NOTE: An earlier version of this report was released as the"Surveillance Camera RFP Template" but has been substantiallyrevised in this edition.]


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rest, see our full IP Camera Training Handbook.

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2014 Ipvm Ip Camera Fundamentals