Calculating Property Corners and Performing a Localization€¦ · Webinar Agenda • Review of Project Scenario • Example of Metes and Bounds • Localization Process Explained

Oscar R. Cantu’October 2009

Calculating Property Corners and Calculating Property Corners and Performing a LocalizationPerforming a Localization

• For access to previously offered webinars and supporting documentation, please go to:

http://www.topconuniversity.com/

Calculating Property Corners and Localization

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• At anytime during today’s webinar, if you have any questions, please type them within the Questions section of your webinar software.

• All questions and answers will be posted as a PDF along with all webinar supporting files on the Topcon University website.


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Webinar AgendaWebinar Agenda• Review of Project Scenario• Example of Metes and Bounds• Localization Process Explained

• New TopSURV Job to Support Localization• Get Rover Receiver into Fixed Solution• Calculate Points in Direction

• Localization Process in TopSURV

• You need to manually calculate the boundary of property from a metes and bounds description.

• However, you are not in the office to take advantage of a CAD software package.

Project ScenarioProject Scenario

• Start with TopSURV data collection software.

• While in the field, there are powerful coordinate geometry (COGO) routines that offer the ability to create calculated points based off of an historical survey with a metes and bounds description.


• This is an example of a property’s metes and bounds description that will be used for this webinar topic.

Example of Metes and BoundsExample of Metes and BoundsCalculating Property Corners and Localization

(Page 481)

• In TopSURV data collection software, a Localization is the process of representing all GNSS field work in a local coordinate system.

• Three main types of Localizations are:– Single Point – All field work is “on the ground” and

checkable with a total station or a pull tape. North is Geodetic North (since that is all that you know). As you leave the single point that is used for a Localization, you become less confident.

– Two Point – used when the intent is to retrace a historical field survey. Used to reference a Bearing Basis. Also referred to as, “Getting on line”.

What is a Localization?What is a Localization?Calculating Property Corners and Localization

– Multiple Point – commonly referred to as, “boxing your site”. As you work within this multiple point localization, your confidence is high. As you leave the polygon, your confidence becomes less and less. This makes sense, since you are leaving the area were “ground” is defined.

What is a Localization?What is a Localization?Calculating Property Corners and Localization

• Local Points – the word “local” implies that their coordinates only mean anything to YOU. They are your local coordinates for your specific project site.

• During the Localization process, the positions of your Local coordinates are never changed. Instead, they are what is “held” and how your Latitude, Longitude, Ellipsoidal Heights will be displayed.

• They are simply “points in space”, design / calculated.

• WGS-84 Points – actual field observations initially displayed in Latitude, Longitude, and Ellipsoidal Heights.

• Per your selections, they will be rotated and least square adjusted to fit your local points.

• Residuals will indicate how much these geodetic positions have moved to fit your local points.


• Since we know that a few steps from now we are going to perform a Localization within TopSURV data collection software, we will first create a job to support that.

• Once the new field job is made, the next step will be to generate the Local coordinates that will be used in the Localization.

• Next, we will physically occupy the property corners in the field and cautiously take our field measurements (WGS-84 Observations).

• A Localization is then the pairing up of Local coordinates and field measurements (WGS-84 Observations).

New TopSURV Job to Support LocalizationNew TopSURV Job to Support Localization

• Tap the New button and work you way (from top to bottom) down each screen.

• Within the Survey Style screen, ensure to select the proper GPS+ Configuration that supports your specific hardware, method of surveying, and custom settings.

New TopSURV Job to Support LocalizationNew TopSURV Job to Support LocalizationCalculating Property Corners and Localization

• Since we know that the eventual intent for this field project will be to perform a Localization, we will want to declare that the field job’s initial Projection is set to None, its Datum is declared to be WGS84, and Geoid model is None.

• This makes sense, since during the moments that we are performing a Localization within TopSURV (the pairing up of Local coordinates and WGS-84 Observations) we are creating our own custom cartographic projection for our specific project site.

• Therefore, by initially selecting that the new job’s Projection is set to None, you are declaring that you will be performing a Localization a few steps later. Easy.


• The options within the Distance Units screen, Display Options, and Audible Alarms are user definable. Shown above are commonly used settings.

• Since we know that a few steps from now we are going to enter in the directions and distances from a metes and bounds description, we will declare that TopSURV displays Directions in Bearings.


• For supporting information on this process, please see the Topcon University webinar entitled, “GRS-1 Receiver: Connecting to a Real Time Network”.

Get Rover Receiver into Fixed SolutionGet Rover Receiver into Fixed SolutionCalculating Property Corners and Localization

• With the TopSURV field job now made, the next step will be to establish a communication link to your GNSS receiver and get your rover into a Fixed solution.


http://www.topconuniversity.com/index.php/training


Calculate Points in DirectionCalculate Points in DirectionCalculating Property Corners and Localization

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• We are now ready to begin calculating Local points within our TopSURV field job.

• They will based on the directions and distances shown in our example.


• From the TopSURV main menu, tap the COGO (coordinate geometry) icon and select Point in Direction to being manually creating our Local coordinates for our Localization.

• Recall that at this moment, this is an empty / new job without any points in it yet.


• Since there are no points in the job, you can short cut to the job’s current point listing within the Topcon logo (context menu) at upper left corner.

• Here you can tap the Add button to begin manually creating a starting point with Local coordinates.


• The overall intent is to declare values that are large enough where, while working in the field, we will avoid having negative coordinates.

• It is common to use a Northing, Easting, and Elevation of 10000, 20000, and 500.

• Once made, you can then use existing point number 1 as an origin for your calculated Point in Direction.


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• Our From Point is existing point number 1 (that you just made).

• For this example, the Bearing from point 1 is N 45°00’ E with a distance of 400.00 feet.

• At that direction and distance will be the resulting calculated point number 2.


• After entering in the record information (N 45°00’ E with a distance of 400.00 feet) ensure to declare the COGO Point Number and Code for the resulting calculated point. Tap the Calculate button.

• TopSURV will immediately show you the resulting coordinates. However, the calculated point (point 2) has not been made yet.

• You have an opportunity to tap the Map tab and visually confirm results.


• After visually confirming within the Map view, you can migrate back to the Results tab. Once satisfied, tap the Save button to have the resulting COGO point stored within the job’s current point list.

• Without leaving this screen, return to the Point in Direction tab and continue your way around the metes and bounds description.

• Now the steps repeat.


• Once done, you can exit out of the Point in Direction routine and return to the Main Menu.

• From there, it is common to tap the Map icon and ensure that your resulting calculated points, “look right”.


• Lastly, it is common at this point to pause and export the resulting local (calculated) coordinates that were just made to a simple text file…for recording keeping purposes.

• This can be done by following TopSURV’s Export / To File routine.

……any questions?any questions?Calculating Property Corners and Localization

Localization Process in TopSURVLocalization Process in TopSURVCalculating Property Corners and Localization

• At this point, we have accomplished:– Creating a TopSURV field job– Rover receiver is in a Fixed solution– Added a new Local point– Calculated all property corners based

off of a historical survey (metes and bounds description)

• So, all Local points have been made.

• The next step will be to physically observe property corners in the field and Localize.


• From the TopSURV main menu, tap the Setup GPS icon and select Localization.

• Initially, you see within the Localization setup screen that there are no “point pairs” shown. A localization has not been performed in this job yet. Therefore, any and all observations made with your rover receiver will be shown in Latitudes, Longitudes, and Ellipsoidal Heights.

• To begin the process of having your field work shown in a Local coordinate system, tap the Add button.


• Work you way (from top to bottom) down the Add Point screen.• The overall intent is to declare that a Local Point (in our example, point number 1) is

the same Horizontally and Vertically and a WGS-84 Point (a shot on the ground).• At this moment, we have not taken our physical shot on the ground. We are about

to.• So you have an opportunity to declare what the point name / number of the WGS-84

Point will be.


• There are many point naming conventions.

• Some choose to name their WGS-84 Points with the suffix GPS at the end, some use the letter H for Horizontal or V for Vertical at the end, etc…

• For our example, since the local / calculated points are all numbered in the 1 to 99 range, it is common to simply add 100 to the corresponding WGS-84 point name.

• This will result in the pairing of Local Point number 1 and WGS-84 Point 101 for easy recall later.

• Then Local Point 2 and WGS-84 Point 102, and so on…


• Stop. At this moment, you have accomplished a One Point Localization.

• As mentioned, all remaining GNSS field observations will be displayed in your local coordinate system and are checkable with a total station. You are on the ground.

• Your project’s north direction is Geodetic North (since that is all that we know at this moment)…keep going.


• Tap the Add button to pair up more Local Points and WGS-84 Points.

• For this example, the local (calculated) points are horizontal only. We do not know the elevations of all points. Therefore, we will hold the elevation of local point 1 for the entire Localization.

• To do that, ensure to uncheck the Use Vertically box for 2 and 102.


• Stop again. At this moment, we have a Two Point Localization. All GNSS field observations will be rotated to the bearing basis between the local points 1 and 2.

• All GNSS field observations will be shown with elevations relative to local point 1’s elevation of 500 feet.

…keep going.


• After repeating for Local Point 3 and WGS-84 Point 103, notice your horizontal residuals.

• Since you are now using three Local Points and three WGS-84 Points, you have a triangle on top of a triangle. The thee local points are one triangle (on top). The three WGS-84 Points are the other (below).

• The values in the Horizontal Residuals column indicate how much the WGS-84 Points will be least square adjusted to fit your Local Points.


• After that, the process repeats. Shown above, all six Local Points (1 to 6) were paired up with corresponding WGS-84 Points (101 to 106).

• As you can see, only the Local Point numbered 1 is being used for elevation.

• Again, the Horizontal Residuals column indicates how all WGS-84 Points (shots on the ground) fit within their paired Local Points.

……any questions?any questions?Calculating Property Corners and Localization

Calculating Property Corners and Calculating Property Corners and Performing a LocalizationPerforming a Localization

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Calculating Property Corners and Performing a Localization€¦ · Webinar Agenda • Review of Project Scenario • Example of Metes and Bounds • Localization Process Explained