Word Pro - MultiCam Instruction Manual V1.0MultiCam’s 1.3 megapixel (1280×1024) CMOS arrays require a lens capable of producing a 19.67 mm image circle. Therefore, F-mount and large

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MultiCam

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A Multi-Spectral Imager for Airborne, Laboratory and Field Applications

Instruction Manual

January 2008

Version 1.0

MULTICAM SPECIFICATION SHEET

GPS, AHRS (optional)Auxiliary equipmentEach camera separately setGain, offset, exposure7.0 fps for 5 cameras (USB limited)Frame rate (max)synchronized (all cameras)Image captureuser selectedSpectral bandsInterchangeable, F or C mountLensesazimuth, elevation, rotationBoresight adjustmentmulti-spectralImagingup to 5# of cameras

Features

MonochromeCMOS type10 bits Resolution500 fps (CMOS alone)Max frame rate TrueSNAP (electronic shutter)Exposure control19.67 mmDetector diagonalCMOSDetector type1,280 × 1024, 12 µmDetector resolution, pixel size

Detectors

customFilter holders4mm × 50.8mm × 50.8mm Allocated volume (up to)between optics and CMOSPosition

Bandpass filters

Radiometric calibrationImage co-registrationCamera alignment / boresightingGPS / AHRS data capture and time synch to imageryCamera control via USB (live preview, data capture, camera setting)Software

Side or down lookingSensor mount8.6 kg5.9 kg Mass (no lenses)254 mm / 10.0 in212 mm / 8.3 inHeight 333 mm / 13.1 in210 mm / 8.3 inWidth 328 mm / 12.9 in270 mm / 10.6 inLength PentaCamQuadCamMechanical

USBImage transferExternalSupply location5 AmpsMax current 5 VDCSupply voltage

Electrical

MultiCam Instruction Manual Version 1.0 OKSI

Table of Contents

30Installing the Software on Additional Computers.11 . . . . . . . . . . . . . . . . . . . . . . . . . . .27Radiometric Calibration Software.10.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Co-registration Software.10.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25ENVI Software.10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25Modulation Transfer Function.9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Camera Settings for Airborne Imaging.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Camera Gain Linearity.7.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20Radiometric Calibration.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Image Files.6.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19GPS and AHRS Files.6.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Files and Headers.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Frame Rate Study.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Alignment / Boresighting.4.6.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Settings Menu.4.6.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13File Menu.4.6.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Section 7 - Additional Menus.4.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Section 6 - Zoom Control.4.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Section 4 - Live View Controls.4.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Sections 3 and 5 - GPS / AHRS Control and Display.4.3 . . . . . . . . . . . . . . . . . . . . . . . .10Section 2 - Video Controls.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Section 1 - Image Display.4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Software.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Driver Installation.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Bandpass Filters.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Optics.1.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3External Connections.1.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Camera Alignment Hardware.1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Hardware Mounting.1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Hardware.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PageSection


List of Figures

30Image cube save pop-up41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Dark field file selection pop-up.40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Gain image file selection pop-up.39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28DN pop-up.38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Exposure time and f/# inputs.37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27RGB co-registration image.36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26Reference cube pop-up.35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26QuadCam on ENVI toolbar.34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Normalized response vs. camera gain.33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Calibration data.32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Calibration using a calibrated irradiance lamp.31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Irradiance calculation with bandpass filter.30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Crosshair on alignment target.29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Adjustment tool and hardware.28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Alignment pop-up (PentaCam).27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Set Directory pop-up.26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Gain / Offset pop-up (PentaCam).25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Camera Settings pop-up (PentaCam).24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Settings menu selection.23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14File menu selection.22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Live view: (a) controls, (b) schematic (for PentaCam), and (c) ‘Sync Time’ button.21 . .12Crossbow AHRS (a) and Garmin GPSMAP76 (b).20 . . . . . . . . . . . . . . . . . . . . . . . . . . . .11GPS / AHRS: (a) controls and (b) display.19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Video controls.18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Graphical user interface (PentaCam).17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Sixth driver installation pop-up.16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Fifth driver installation pop-up.15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Fourth driver installation pop-up.14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Third driver installation pop-up.13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Second driver installation pop-up.12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Initial driver installation pop-up.11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Set screw loosening (a) and filter holder removal with tweezers (b).10 . . . . . . . . . . . . . . .6QuadCam oriented for filter displacement (a) and filter cover removal (b).9 . . . . . . . . . .5Top cover / side removal: (a) PentaCam and (b) QuadCam.8 . . . . . . . . . . . . . . . . . . . . . .5Filter holder.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Imaging sensor with filter cover.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3C-style mounting provisions: (a) PentaCam and (b) a single MultiCam sensor.5 . . . . . .3External connections: (a) PentaCam and (b) QuadCam.4 . . . . . . . . . . . . . . . . . . . . . . . . .2

Alignment hardware: (a) shown with image sensor and (b) 2D CAD rendering oftip-tilt screw.

3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2MultiCam mounting provisions: (a) PentaCam and (b) QuadCam.2 . . . . . . . . . . . . . . . .1System components: (a) PentaCam and (b) QuadCam.1 . . . . . . . . . . . . . . . . . . . . . . . . . .

PageFigure


List of Tables

30Contents of radiance cube header file.15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25MultiCam’s MTF results.14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Suggested ‘starting point’ camera settings for airborne imaging.13 . . . . . . . . . . . . . . . . .22Calibration camera settings.12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19Frame rate study.11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Alignment / boresighting controls.10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Gain / Offset controls.9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Camera Settings controls.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Digital zoom controls.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Live view controls.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11GPS / AHRS controls and display.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Video capture controls.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Dimensions allocated for bandpass filter.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Fujinon CF35HA - 1 specifications2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Component description.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PageTable


1 HARDWARE

While it is not necessary to have a comprehensive understanding of the MultiCam hardware inorder to collect data, a low-level understanding of the components will help the user betterunderstand how the system operates.

The items seen in Figure 1 represent the main components of the MultiCam system. A descrip-tion of each of these components is found in Table 1.

(b)(a)

Alignment Screw

Filter Cover

USB Connection

Power Connection

USB Hub

Sensor Housing

Mounting Hardware

USB Hub

USB Connection

Power Connection

Filter Cover

Alignment Screw

Sensor Housing

Mounting Hardware

Figure 1. System components: (a) PentaCam and (b) QuadCam.

Table 1. Component description.

Means of fixturing MultiCamMounting HardwareContains a CMOS imaging arraySensor HousingUsed to point the sensor housingAlignment ScrewProvides access to bandpass filterFilter CoverConnection used to provide 5VDC to the image sensorsPower ConnectionConnection used for camera communication with the USB hubUSB ConnectionConverts one USB signal into multiple signals and vice-versaUSB Hub

FunctionComponent

1.1 Hardware mounting

MultiCam has been designed so that it can be mounted on its side or from the bottom. The sideand bottom mounting provisions, shown in Figure 2, allow data to be collected in either thehorizontal or vertical directions.


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(b)(a)

¼ - 20 Through Holes (3” on Center)

¼ - 20 Tapped Hole

¼ - 20 holes for tripod mount

¼” through holes breadboard mounting

Figure 2. MultiCam mounting provisions: (a) PentaCam and (b) QuadCam.

As seen Figure 2, the mounting hardware provides both ¼ - 20 tapped and through holes.Specifically, the bolt pattern has been machined so the unit can attached to standard opticalbreadboards or a tripod.

1.2 Camera alignment hardware

Each CMOS sensor has been equipped with a three degree-of-freedom (DOF) fixture allowing itto be accurately aligned. Specifically, each sensor can be rotated, tipped, and tilted via thespecial mounting screws shown in Figure 3.

(b)(a.)

1. Adjustment nipple

2. Keyed nipple adjuster

3. Holding screw

4. Adjustment plate

5. Base plate

Tip - Tilt Screw

Rotation Fixture

Figure 3. Alignment hardware: (a) shown with image sensor and (b) 2D CAD rendering of atip-tilt screw.


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The rotation fixture labeled in Figure 3 allows the imaging sensor to rotate about the center of itsCMOS array (i.e., the optical axis). This rotation gives the user the ability to orient each sensorso the images returned are square each other.

The tip-tilt screws seen in Figure 3 provide camera pointing. These special screws work byusing a threaded nipple (1) to manipulate the separation between the adjustment and base plates.Using three tip-tilt screws together allows the user to change the azimuth and elevation angles ofeach sensor. After alignment, the position of each sensor is locked in place with a cap screw (3).A thorough description of the alignment procedure is found in Section 4.6.3.

1.3 External connections

Only two connections are needed to operate the MultiCam hardware. A single USB connectionis needed for transferring image data, while +5 VDC is needed to power the image sensors andsupporting electronics. The external connections are shown in Figure 4.

(b)(a)

+5VDCUSB

USB

+5VDC

Figure 4. External connections: (a) PentaCam and (b) QuadCam.

1.4 Optics

Each of MultiCam’s imaging sensors has a provision for C-mount fore optics. The C-stylemounting provisions are shown in Figure 5.

(b)(a)

‘C’ mount thread‘C’ mount thread

Figure 5. C-style mounting provisions: (a) PentaCam and (b) a single MultiCam sensor.


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While C-style lens mounts have been chosen for MultiCam’s sensors, adapters can be purchasedallowing for the use of F-mount lenses.

MultiCam’s 1.3 megapixel (1280×1024) CMOS arrays require a lens capable of producing a19.67 mm image circle. Therefore, F-mount and large format C-mount lenses are needed toprevent image degradation due to vignetting. Typically, 1” format Fujinon lenses, with 35 mmfocal length, have been shipped with the MultiCam hardware. The mechanical specifications ofthese lenses are listed in Table 2.

Table 2. Fujinon CF35HA - 1 specifications.

CMount48.5 (at ∞)Length51 mmDiameter180 gMassf1.4 - f22Iris Range

Specified ValueFeature

2 BANDPASS FILTERS In each MultiCam sensor housing, a bandpass filter can be inserted in between the fore opticsand the CMOS array. This feature eliminates the need to purchase a new filter each time a lenschange is desired. The filter cover, which is labeled in Figure 6, covers the volume allocated forthe filter assembly. The dimensions of the filter volume are listed in Table 3.

Filter Cover

Figure 6. Imaging sensor with filter cover.


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Table 3. Dimensions allocated for the bandpass filter.

50.8 mmLength50.8 mmWidth4 mmHeight

ValueDimension

Commercial off the shelf (COTS) filters of many different sizes can be inserted into the filtervolume by machining custom filter holders. Four filter holders that accommodate 25 mm diame-ter filters are shipped with each MultiCam system. One such filter holder is shown in Figure 7.

Set Screw

Bandpass filter, Ø = 25mm

Figure 7. Filter holder.

Removal and installation of the bandpass filters into the MultiCam hardware is very straightfor-ward. First, remove the top cover (PentaCam) or the sides (QuadCam).

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Figure 8. Top cover / side removal: (a) PentaCam and (b) QuadCam.


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Next, flip the system over so that it is oriented as shown in Figure 9a. Now the filter cover canbe removed as shown in Figure 9b.

(b)(a)

0 – 80 Screw

Figure 9. QuadCam oriented for filter replacement (a) and filter cover removal (b).

Loosening the two set screws, which are used to secure the filter holder, is the next step in thefilter replacement process. This step is shown in Figure 10a.

(b)(a)

Tweezers

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Figure 10. Set screw loosening (a) and filter holder removal with tweezers (b).

The final step, which is illustrated in Figure 10b, involves removing the filter holder. It is impor-tant to note the orientation of the filter holder as it is removed from the sensor body. Orientationis critical because the holder is not symmetrical about the center hole.

With the filter holder removed, a new filter can be inserted and secured with the holder’s setscrew (see Figure 7). After changing the filter, the filter assembly should be repositioned insidethe camera body and secured. It is important make sure that the set screws used to secure thefilter holder in place are securely tightened because these screws also aid in holding the lens inposition.


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3 DRIVER INSTALLATION

If it is necessary to install the sensor drivers, a pop-up window will be displayed after the systemis connected via USB. The initial pop-up screen is shown in Figure 11. As seen, the bottomradio button, which is labeled ‘No, not this time,’ should be selected.

Figure 11. Initial driver installation pop-up.

After selecting the ‘Next’ button, the screen shown in Figure 12 appears. Select, ‘Install from aspecific location (Advanced).’

Z

Figure 12. Second driver installation pop-up.

In the next pop-up, which is shown in Figure 13, the second option should be selected. Specifi-cally, choose ‘Include this location in the search:’ and ‘Browse’ to C:\MultiCam\.


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A

Figure 13. Third driver installation pop-up.

Figure 14 shows the fourth driver installation pop-up screen. On this screen, select the topoption and hit ‘Next.’

Figure 14. Fourth driver installation pop-up.

Select ‘Continue Anyway’ when the fifth pop-up appears.


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Figure 15. Fifth driver installation pop-up.

The final pop-up is shown in Figure 16. On this screen, select ‘Browse,’ then point to C:\Multi-Cam select ezusb.sys, and press ‘OK.’ This completes the driver installation.

Figure 16. Sixth driver installation pop-up.

4 SOFTWARE

The Graphical User Interface (GUI) used to control the MultiCam system is shown in Figure 17.Notice that the GUI has been divided into seven sections. Each of these sections is describedbelow in detail.


9

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Figure 17. Graphical user interface (PentaCam).

4.1 Section 1 - Image display

The image window, labeled ‘1’ in Figure 17, is used to display data collected by the imagingsensors. Specifically, one to five (for PentaCam) images can be displayed depending on theuser’s preference.

4.2 Section 2 - Video controls

The video capture controls are shown in Figure 18. A description of each control is found inTable 4.

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Figure 18. Video controls.


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Table 4. Video capture controls.

Stops live image display and /or data captureButtonStopInitiates the saving of image data to diskButtonCaptureInitiates live image display without saving to diskButtonLive

When checked, the image display is updated during imagecapture. Live image display during image capture willdecrease the rate at which frames are saved to disk.

Check boxLive Capture

DescriptionControl TypeControl Label

4.3 Sections 3 and 5 - GPS/AHRS control and display

Sections 3 and 5 of the GUI contain the controls and display needed for GPS and AHRS datacapture. In order to activate these features, the user must request the system to search for GPSand AHRS devices upon startup. This procedure is described in greater detail in Section 4.6.2.

Figure 19 displays the GPS / AHRS controls and display. Table 5 describes the contents ofFigure 19 in detail.

(b)(a)

..

Figure 19. GPS / AHRS: (a) controls and (b) display.

Table 5. GPS / AHRS controls and display.

Displays altitude data during GPS data captureNumeric DisplayAltDisplays latitude data during GPS data captureNumeric DisplayLatDisplays longitude data during GPS data captureNumeric DisplayLonDisplays yaw data during AHRS data captureNumeric DisplayYawDisplays pitch data during AHRS data captureNumeric DisplayPitchDisplays roll data during AHRS data captureNumeric DisplayRollStops GPS and /or AHRS data capture Button controlStopInitiates GPS and /or AHRS data capture Button controlCapture

When checked, a data file containing GPS data will becreated in the root directory Check box GPS Log

When checked, a data file containing AHRS data will becreated in the root directory Check box AHRS Log

DescriptionTypeLabel

The MultiCam software is configured to work with the AHRS400 made by Crossbow(www.xbow.com). Because different inertial systems have different packet protocols and serialcommands, the MultiCam software does not support other INS devices. An image of theAHRS400 is seen in Figure 20a.


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(b)(a)

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Figure 20. Crossbow AHRS (a) and Garmin GPSMAP76 (b).

The GPS system used during software testing was the GARMIN GPSMAP76, seen in Figure20b. However, the GPSMAP76 produces standard NMEA packets via RS-232. Therefore, otherGPS systems that comply to this protocol should work with the PentaCam software.

4.4 Section 4 - Live view controls

Section 4 contains controls used to select which cameras will be displayed when the ‘Live’button (see Figure 18) is pressed. In addition, Section 4 contains a schematic to help the userdetermine the physical position of each sensor and a ‘Sync Time’ button used to synchronize theWindows clock with the incoming GPS signal (when GPS is active).

Figure 21 shows the controls and the PentaCam schematic. Table 6 describes each in moredetail.

(c)(b)(a)

...

Figure 21. Live view: (a) controls, (b) schematic (for PentaCam), and (c) ‘Sync Time’ button.


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Table 6. Live view controls.

*PentaCam only

Used to (re)synchronize the Windows clock with GPS time. Note thatthe Windows clock is automatically synchronized at software start upwhen a GPS signal is present

ButtonSyncTime

Used to provide the user with a reference location for each of thecameras. The numbers shown indicate the position of each sensorrelative to the USB and power inputs

ImageCameraView

When checked, data captured by Cam5 is displayed during live previewCheck box Cam5*When checked, data captured by Cam4 is displayed during live previewCheck box Cam4When checked, data captured by Cam3 is displayed during live previewCheck box Cam3When checked, data captured by Cam2 is displayed during live previewCheck box Cam2When checked, data captured by Cam1 is displayed during live previewCheck box Cam1

DescriptionType Label

4.5 Section 6 - Zoom control

Section 6 contains the controls used to manipulate the display’s digital zoom. It should be noted,however, that the digital zoom buttons are only active when a single camera is selected for liveviewing or alignment.

The digital zoom controls are shown and described in Table 7.

Table 7. Digital zoom controls.

When pressed, a control box appears in the upper right-hand corner ofthe display window. This control box can be dragged with the mouseto change the region of the image displayed in the preview window.

Button

Eliminates all digital zoom and decimationButton

Decreases the display’s digital zoomButton

Increases the display’s digital zoomButton DescriptionControl TypeImage

4.6 Section 7 - Additional menus

Section 7 contains menu controls used to set the root directory, change camera settings, andperform camera alignment. The contents of each menu is described below.

4.6.1 File menu

When the ‘File’ menu is selected, as shown in Figure 22, the user is given the option to exit theprogram.


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.Figure 22. File menu selection.

4.6.2 Settings menu

Several options are available when the ‘Settings’ menu is selected. These options are shown inFigure 23.

.Figure 23. Settings menu selection.

When ‘Camera Settings’ is selected, a pop-up screen appears. This pop-up screen, which isshown in Figure 24, allows the user to control various aspects of image capture and display.Details associated with these controls are listed in Table 8.

blue green red IR1 IR2

Figure 24. Camera Settings pop-up (PentaCam).

Table 8. Camera Setting controls.

Allows the user to enter a name for each camera (this nameappears in Section 4 of the GUI)String Cam Name

When checked, image data is saved after the ‘Capture’ button(Figure 18) is pressedCheck box Cam Capture

Time, from 1 to 321 ms, that each sensor integrates Numeric Exposure Time

DescriptionControlType Label


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Changes the current camera settings to the default camerasettingsButtonGo to Default

Saves the current camera settings as defaultButtonSet As Default

Removes the ‘Camera Settings’ pop-up from the screen withoutimplementing the current settingsButtonCancel

Implements the current settings ButtonOKUsed to select the baud rate of an incoming GPS signalList BoxGPS Baud Rate

When checked, the MultiCam software will look for a GPSdevice during startupCheck box Use GPS

When checked, the MultiCam software will look for a AHRSdevice during startupCheck box Use AHRS

Determines the number of frames saved to disk after the‘Capture’ button (Figure 18) is pressedNumeric Capture Frames

DescriptionControlType Label

The second option located on the ‘Settings’ menu brings up the gain and offset controls. Thesecontrols are shown in Figure 25 and described in Table 9.

.

Figure 25. Gain / Offset pop-up (PentaCam).

Table 9. Gain / Offset controls.

Number, between 0 and 3300, used to set the sensor gain(Note: high number is actually lower gain.)Slider / Txt BoxGain

DescriptionControl Type Label


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Changes the current settings to the default settingsButtonGo ToDefault

Saves the current settings as defaultButtonSet AsDefault

Removes the ‘Gain / Offset’ pop-up from the screen withoutimplementing the current settingsButtonCancel

Implements the current settings ButtonOK

Number, between -3300 and 3300, used to set the sensoroffset Slider / Txt BoxOffset


The final option on the ‘Settings’ menu is ‘Set Directory.’ When this option is selected thepop-up in Figure 26 appears.

Figure 26. Set Directory pop-up.

The ‘Set Directory’ pop-up allows the user to select the folder in which captured data files (GPS,AHRS, image) are saved.

4.6.3 Alignment / boresighting

As discussed in Section 1.2, the MultiCam sensors have special alignment screws that allow theazimuth and elevation angles of each sensor to be manipulated. Alignment is achieved wheneach lens is oriented so that it is parallel with the other lenses. When the lenses are parallel toeach other, the difference between each sensor’s field of view is minimized (when the lenses arefocused to near infinity).


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There is no immediate need to modify the alignment when the system is received (the system isaligned before shipment). However, all of the hardware and software tools needed for alignmentare available if alignment becomes necessary.

Camera alignment begins by removing the cover of the MultiCam system (see Figure 8).

Next, use the ‘Alignment’ menu to open up the pop-up seen in Figure 27. The contents of theAlignment pop-up are described in Table 10.

.

Figure 27. Alignment pop-up (PentaCam).

Table 10. Alignment / boresighting controls.

Stops live image displayButtonStopApplies the current settingsButtonApply

Overlays a crosshair on the center pixels of the displayedimageCheck boxCenter Cross

Displays the Align Camera imageRadio buttonAlign CamDisplays the Ref Camera imageRadio buttonRef Cam

Initiates a routine where the Align Camera image is added tothe Ref Camera image Radio buttonSummation

Initiates a routine where the Align Camera image is subtractedfrom the Ref Camera imageRadio buttonSubtraction

Controls which sensor is the align sensorRadio buttonAlign CameraControls which sensor is the reference sensorRadio buttonRef Camera



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Adjustment of the alignment screws is done with a special tool. This tool is used to manipulatethe hardware described in Figure 3. The tool, along with the alignment hardware, is shown isFigure 28.

Figure 28. Adjustment tool and hardware.

In order to achieve parallel lens orientation, an alignment target is placed at a distance and thetip-tilt screws are adjusted until the center crosshair is on top of its target. This process is shownin Figure 29.

A

Figure 29. Crosshair on alignment target.


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The alignment target shown in Figure 29 is simply a true-scale print out of MultiCam’s base. Acopy of the alignment target has been shipped with the system. Alignment is achieved wheneach sensor’s center crosshair is overlayed on its target. The software’s digital zoom capabilitiesshould be used increase the ability to achieve true alignment.

5 FRAME RATE STUDY

The maximum frame rate of the MultiCam system, shown in Table 11, was determined byreducing the exposure time to 1ms and collecting 10 images per camera. Therefore, the framerate reported is the average frame rate during the capture of 10 images. Note that the ‘LiveCapture’ check box (Figure 18) was disabled during this study.

Table 11. Frame rate study.

7.1507.078156.9405.781146.6304.563136.1203.281125.2101.90611

Frames/secImagesCaptured

Total CaptureDuration (s)

IntegrationTime (ms)

# ofCameras

6 FILES AND HEADERS

When image, GPS, and AHRS data is captured, PentaCam’s software creates data files and savesthem in the folder selected from the Settings menu (Figure 26). Sections 6.1 and 6.2 describe thesaved files.

6.1 GPS and AHRS files

GPS and AHRS data files are saved in the root directory as a text file. The files are named usingthe start time, date, and file type. For example, a GPS file captured on December 1, 2006 at 1:00PM is given the following name:

13.00.00 12 01 2006 gps.txt

GPS and AHRS files are space delimited. Therefore, they are best viewed using a spreadsheetprogram.

6.2 Image files

When image data are captured, a header and an image file are created. The header is a text filethat contains information about camera settings and capture time. Header files are named usingthe capture time, date, and camera number. For example, a header captured on December 1,2006 at 1:00 PM with camera 4 is given the following name:

13.00.00 12 01 2006 Camera4.hdr


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The second file created during image capture is the image data file. This file has a .fla extensionand is saved in binary format. The image file, combined with its header, is formatted to openusing ENVI (http://www.ittvis.com/envi/index.asp).

7 RADIOMETRIC CALIBRATION

Before shipment, each MultiCam sensor is radiometrically calibrated using a lamp of knownirradiance. Specifically, Equation 1 is used to calculate the gain needed to convert digitalnumbers (DNs) into radiometric units. The calibration is valid for specific gain / offset settingsof the camera.

[1]DN = DF + G $ L $ ETf/#2

Where DN is digital number, DF is dark field (in DN units), G is gain, ET is exposure time, f/#is the f-number of the fore optics, and L is irradiance at the entrance to the fore optics. Units forL do not matter as long as they are consistent when performing the calibration and subsequentlyconverting image data to radiance.

In general, the terms in the equation, DN, DF, G, and L are matrices represented as a 2D image.The L matrix has the same value at all elements. ET and f/# are scalars. All these analyses canbe performed as ‘image’ analysis within ENVI.

In order to calculate the incident irradiance on the fore optics, the area under the lamp’s irradi-ance curve is determined in the region bounded by a bandpass filter. A graphical representationof the area calculation is shown in Figure 30, while the mathematical representation is seen inEquation 2.


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Irradiance Calculation

0

10

20

30

40

50

60

70

80

90

400 420 440 460 480 500 520 540

wavelength (nm)

tran

smis

sion

(%)

0

5

10

15

20

25

30

35

40

45

irrad

ianc

e (m

W/m

^2/n

m)

Bandpass filterCalibration lamp

Irradiance Area

Figure 30. Irradiance calculation with bandpass filter.

[2]L ==0

∞FT $ LL $ ¿

In Equation 2, FT is the filter transmission, LL is the irradiance of the calibration lamp, and is the wavelength step size used for numerical integration.

Once a gain image, G, has been calculated using Equations 1 and 2 for some f/# and ET, thecalibration equation can be generalized to account of any f/# and ET. The general calibrationequation is shown in Equation 3 (DF image should be captured under field conditions, since itdepends on temperature).

[3]DN = DF + (G $ f/#R2 $ETR $ L)

Where :

[5]ETR =ETnET0

[4]f/#R =f/#0f/#n

The subscript values in Equations 4 and 5 distinguish between the reference f/# and ET (given avalue of 0) and the f/# and ET for measurement n.

Gain images, calculated using Equation 1, for each sensor (with its specific bandpass filter inplace) have been shipped with the system (on the CD). The calibration f/# and exposure time(f/#0 and ET0) have already been accounted for in the gain images, and therefore, irradiance at


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the entrance to the fore optics can be determined by plugging in the values for DN, DF, f/#n, andETn into Equation 6.

[6]L =(DN −DF) $ f/#n

2

G $ ETn

Section 9.2 describes an ENVI routine shipped with the system. This routine should be used toconvert raw images (DN units) to radiometric images (radiometric units). However, all of thecalculations can be done in ENVI once the DN, DF, and G images are saved.

The gain, offset, and exposure settings used during calibration are listed in Table 12. An imageof the setup used to collect the calibration data is shown in Figure 31. As seen, the illuminationproduced by the calibration lamp is reflected off spectralon before being collected by the foreoptics.

Table 12. Calibration camera settings.

2.81000800IR252.810003,200IR142.810001,000Red32.810001,650Green22.810001,200Blue1f/#Exposure Time (ms)Camera OffsetCamera GainFilter Camera#

Calibration Lamp

Spectralon

Stray Light Shield

MultiCam

Figure 31. Calibration setup using a calibrated irradiance lamp.


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Calibration Data

0

10

20

30

40

50

60

70

80

90

100

350 450 550 650 750 850 950 1050 1150

Wavelength (nm)

Perc

ent (

%)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Rad

ianc

e (µ

w/c

m^2

/sr/n

m)

36297458354653656430MV13 QESigma Lens35329Oriel Lamp

.

Figure 32. Calibration data.

The transmission of each bandpass filter, detector QE, lens transmission, and lamp radiance isshown in Figure 32. Note that the lens transmission has been normalized to a maximum trans-mission of 90%.

7.1 Camera gain linearity

In order to know if it is appropriate to apply (use in calibration) the gain images generated by thecalibration at a single camera gain to other gain settings, it is import to understand how changesin camera gain affect the response (DNs) of the detector. Figure 33 is a plot of relative responsevs. camera gain setting. Notice that the response is not linear.


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Figure 33. Normalized response vs. camera gain.

Because the camera’s response to gain changes is not linear, a full characterization of eachsensor should be completed in order to generalize the calibration equations for all camera gainsettings. Alternatively, a calibration could be completed for all camera settings used during datacollection.

8 CAMERA SETTINGS FOR AIRBORNE IMAGING

A study was conducted in order to determine a reasonable set of camera parameters for airborneimaging. These settings are not absolute but can be used as a starting point during aerial datacapture. Data were collected with each image sensor while looking at plant life illuminated bythe sun. The data were captured at f/2.8 in order to minimize the integration time needed toachieve adequate signal while using narrow bandpass filters. Table 13 shows the cameraparameters chosen. Notice that the airborne image settings are identical to the settings usedduring calibration.

Table 13. Suggested ‘starting point’ camera settings for airborne imaging.

*PentaCam only2.81000800IR25*2.810003,200IR142.810001,000Red32.810001,650Green22.810001,200Blue1f/#Exposure Time (ms)Camera OffsetCamera GainFilter Camera#


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9 MODULATION TRANSFER FUNCTION (MTF)The MTF for each sensor / filter / lens combination was calculated using Imatest software.Imatest software is a commercially available package available at www.imatest.com. TheImatest software outputs MTF50, which is a numeric representation of perceived image sharp-ness. Details regarding the setup used to collect the MTF, as well as, the mathematics behindthe calculation are discussed in detail at:

http://www.imatest.com/docs/sharpness.html#interpretation

Table 14 summarizes the results of the MTF study carried out using the MultiCam system.

Table 14. MultiCam’s MTF results.

*PentaCam only16.5OS02219IR25*29.1OS02090IR1429.8OS02749Red331.0OS02329Green227.8

Sigma105 mm

OS02792Blue1

MTF 50(cycles/mm)LensFilter

Model #Filter Camera#

Notice that the MTF50 is relatively constant when the blue, green, red, and IR1 filters are used.However, there is a steep drop-off in the MTF50 for the IR filter. This drop-off is most likelydue to the poor lens performance in the IR region.

10 ENVI SOFTWARE

Two analysis software programs have been shipped with the MultiCam system. The firstprogram is used for image co-registration and the second program is used to apply gain imagesto convert raw images (DN units) to radiometric images (radiometric units).

Before using the ENVI software, the folder named, ‘MultiCam_sav’ must be put in the correctENVI directory.

C:\RSI\IDLXX\products\enviXX\save_add

Note that ‘XX’ in the above address refers to a specific version number. Once the folder isplaced into the directory, a ‘MultiCam’ option will appear on the main ENVI toolbar. Theupdated MultiCam toolbar is shown in Figure 34.


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.

Co-registration

Create Calibration

Figure 34. QuadCam on ENVI toolbar.

10.1 Co-registration software

The objective of the co-registration software is to spatially warp one or more images to match areference image. Warping reduces the spatial differences between images that have not beenremoved by hardware alignment, and correct for paraxial shift due to the displacement of thelenses. However, parallax correction is best applied at infinity, and can not be applied to imagewith objects at different depth of field.

After ‘Co-registration’ has been selected on the ENVI toolbar (Figure 34), the pop-up screenshown in Figure 35 appears.

.

Figure 35. Reference cube pop-up.

The pop-up shown in Figure 35 asks the user to select a reference file. The reference file is atime series of images, i.e., an image cube (.fla extension) produced by a single sensor. The


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images in the reference cube are not warped by the co-registration software. Instead, it is used asthe ‘master’ image to which all other images are matched. After the reference cube has beenselected, the software prompts the user to select up to three additional time-series forco-registration. If less than five cameras (PentaCam) are desired the user can stop the analysisby selecting ‘Cancel.’

The co-registration, not only co-registers the time sequence of images, but also parses the time-sequence and creates multispectral image cubes (of time-synchronized images). Therefore theoutput of the co-registration analysis is a series of image cubes (file extension ‘cub’) saved in thesame directory as the reference data file. The total number of cubes is equal to the number ofimages in each input data file. Each cube contains five (if all five PentaCam cameras are used)images which can be selected to form a RGB color image. This process is further illustrated inFigure 36.

.

Available Bands

Output RGB Image

Figure 36. RGB co-registration image.

Note that the co-registration procedure produces the best results when objects are viewed at largedistances (i.e. ∞). This is due to the paraxial lens displacement.

10.2 Radiometric calibration software

The calibration software shipped with the system can be used to convert digital numbers toradiometric units. The software applies Equation 7, which is simply Equation 3 solved for L.

[7]L = DN −DFG $ f/#R

2 $ ETR

Dimensional analysis of Equation 7 shows that L will have the same radiometric units as thesource used to calculate the gain image (G).


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The radiometric calibration software is started by selecting ‘Create Calibration’ under the Pentaor QuadCam heading on the ENVI toolbar (see Figure 34). Once started, the pop-up shown inFigure 37 appears asking the user to enter the exposure time and f/# of the image undergoingcalibration.

.

Figure 37. Exposure time and f/# inputs.

The exposure time and f/# entered represent ETn and f/#n as described in Equations 4 and 5.

Once the user has entered the appropriate exposure time and f/#, the software prompts the user toenter an image cube with units in DNs. The pop-up used to facilitate this process is shown inFigure 38.

.

Figure 38. DN pop-up.

Next, the software requires the user to input a gain image. The gain image is generated by usinga source of know radiance. Gain images have been shipped with the system (on the CD) but it isgood practice to recalibrate (calculate new gain images) on a regular basis or if any of the opticalhardware changes (lens, filters, etc.). The gain image pop-up is shown in Figure 39.


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.

Figure 39. Gain image file selection pop-up.

The final input required by the software is a dark field image. The dark field should be collectedusing the same (camera) gain, offset, and exposure time as the DN image. The dark field pop-upis shown in Figure 40.

.

Figure 40. Dark field file selection pop-up.

After the dark field image is selected and the software calculates the radiance cubes, the user isasked to save the calibrated images using the pop-up seen in Figure 41.


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.

Figure 41. Image cube save pop-up.

Notice that the default file name for the radiance cube is derived from the current time, currentdate, camera name, and ‘rad’ for radiance. The default file extension is ‘fla.’ However, both thename and file extension can be changed by the user.

In addition to the radiance cube, the calibration software creates a header file (file extension‘hdr’) containing information about the radiance cube and the input images. Table 15 lists theinformation contained in the header file created with the radiance cube. Notice that the headercontains information about the radiance data, as well as, the images used by the ENVI to createthe radiance images.

Table 15. Contents of radiance cube header file.

DN file name & locationcamera gain, offset, & exposure time# of images (bands)

start & end capture timesdark field file locationcreation timecamera name & numberdark field file namecreation date

Field Data (Flight Settings)Lab Calibration DataRadiance Cube

11 INSTALLING THE SOFTWARE ON ADDITIONAL COMPUTERS

The MultiCam software is fully installed and operational on the laptop shipped with the system.However, it is possible to install the software on additional computers.


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Installing the software is straightforward. The CD shipped with the system contains a foldercalled ‘MultiCam Software.’ The contents of this folder contain all of the necessary componentsneeded to run the software, including the camera driver. Therefore, all the user must do to usethe software is copy the ‘MultiCam Software’ folder to the C drive on the new computer. Afterthe software is copied and the system is connected via USB, the user must install the driversusing the process outline in Section 3.


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Documents

Word Pro - MultiCam Instruction Manual V1.0MultiCam’s 1.3 megapixel (1280×1024) CMOS arrays require a lens capable of producing a 19.67 mm image circle. Therefore, F-mount and large