Using NEZ plane in iCMTGIS PRO to stakeout soccer fields

“Is this something your app could help us do with the EOS? . . . We are working with soccer field templates that are interchangeable between any field location. Right now, we have a survey Leica GPS that we can match 2-3 points (usually corners of the field) to the template points. The receiver then matches the rest of the field points. Then we can use navigation to mark the rest of the field. . . . I’m attaching our template pdf as an example and a csv of the points we currently use.”

Yes, we have customers who do geo-referencing and engineering stakeout using iCMTGIS PRO.

The procedure is as follows:

1. Your templates are based on a local coordinate system in the drawing software used for making the templates.

Suppose corner 1 is at (1000, 1000), and the diagonally opposite corner is at (1100, 1200).

You can define a NEZ plane in iCMTGIS PRO by matching the GPS LAT-LON values at these two corners to the (1000,1000) and (1100,1200) NEZ coordinates.

So, you would first record accurate GPS latitude and longitude coordinates at these two kitty-corner points using your EOS receiver. You can use the data collection function in iCMTGIS PRO to record these positions. In the Static Point mode the app will let you stand at each point for 5 or 10 minutes then average all the readings to yield a more accurate result.

To define a NEZ plane in iCMTGIS PRO, first select MENU – Setup then select the distance unit.

Select NEZ. Confirm to set up a new NEZ coordinate system. Tap on Edit.

Enter the plane name of your choice then tap on Control Point.

With “Reference Point” selected as the Control Point, enter the GPS coordinates for the starting point and the corresponding X, Y values. In our example, it would be X = 1000 and Y = 1000. Make sure you specify the correct N, S, E, W designation for the GPS lat-lon.

Now select “Control Point” the Control Point. Enter the GPS coordinates for the other corner and the corresponding X, Y values. In our example, it would be X = 1100 and Y = 1200. Make sure you specify the correct N, S, E, W designation for the GPS lat-lon.

Tap on OK a couple times to go back to main map screen.

2. As you have a text file for the points in your template, you can use Topic Menu – Import TextFile” to import the points and get them displayed in iCMTGIS PRO. If you do not have a text file, you could use the Add Point by Coordinates function in iCMTGIS PRO to add each corner point and enter its X,Y coordinates.

3. Use Setup – Coordinates to switch to the LLA system (lat-lon).

4. Now use GPS – Point Stakeout to mark the points on the ground.

Does iCMTGIS III include NEZ coordinate system functionality so users can calibrate to a non-standard coordinate system?

Yes. Both iCMTGIS II and iCMTGIS III provide the ability to calibrate a NEZ coordinate system in the field. The procedure is as follows.

For example, in iCMTGIS II select Setup/Coordinate System.
Tap on NEZ then tap on OK.
Tap on Edit then enter a Plane Name.
Mark the Control Point option.

With Reference Point selected, enter the corresponding GPS and NEZ coordinates.

Select Control Point then enter the corresponding GPS and NEZ coordinates.

You may use the Pick button to select an existing GPS point, and its coordinates will be automatically entered.
The resultant calibration angle and scale will be displayed.

I just downloaded the new app for the Ipad (Forester GPS GIS App). Could I get the user defined Michigan Georeference coordinate system patch?

You have already created the user-defined coordinate system for Michigan in your CMT-Forester 10 PC software. Information for user-defined coordinate systems is stored in the user_cor.sys file.

To make the user-defined coordinate systems available for use with the Forester GPS GIS app on the iPad, simply copy the user_cor.sys file from your PC to the documents folder for the Forester GPS GIS. If you have user-defined datums as well, then also copy user_dat.sys to the app’s documents folder. If you have defined plain NEZ coordinate system using your PC software, then also copy user_pla.sys to the app’s documents folder. Please change the file names to be in lower-case letters before copying them to the iPad.

iCMTGIS II, iGPSGIS II, Utility Data Collection, Forester GPS GIS, Forester GPS GIS II, Farming GPS GIS and Farming GPS GIS II provide the ability to use various standard coordinate systems as well as special coordinate systems defined by using our PC mapping software. These apps will also let you define a local NEZ plane in the field.

Defining an NEZ coordinate system based on control points

If you will not be using a known control point with known transformation scale and angle for your locality, you could have these values computed based on two points: a Reference Point and a Control Point. It’s best to select these two points near the two opposite corners of your work site. You will need to obtain the coordinates for these same two points in the two different coordinate systems.

To do so, first tap the Control Point check box in the NEZ System screen of  the CMTINC.COM app that provides NEZ setup capability. The pull-down arrow on the same line of this option will show two modes: Reference Point and Control Point.

For each mode, enter the actual LLA values of the GPS coordinates of the point and the NEZ coordinates you wish to assign for the same point. The software will automatically fill the Angle and Scale fields with the computed values. (If you have survey-grade GPS, you could use it to get the LLA coordinates for these points.)

Save your settings, then return to Map View. When you tap on the map, you will see that the coordinates are now displayed in terms of the NEZ system.

Defining an NEZ coordinate system based on known scale and angle

Some of you may wish to display the Feature coordinates in reference to a local Cartesian coordinate system. For example, you may wish to express the location of the buildings, wells or towers on a large complex in terms of their X-Y position with respect to a reference location on the campus. The reference location coordinates are usually set to values that permit all the locations on the resultant map to be expressed with positive X and Y values. For instance, if the map spans an extent of about 3500 ft both ways, and the reference location is set near the center of the campus, then the reference position could be assigned a value of (2000, 2000).

The local coordinate system is called an NEZ coordinate system with the N (Northing) corresponding to the Y value, the E (Easting) corresponding to the X value, and the Z (Z-value) corresponding to the vertical distance along the Z-axis.

The relationship between the LLA plane and the NEZ plane consists of a rotation and a scale change. How would you transform the LLA coordinates to the NEZ coordinates? Leave the computations to the software program, but you will need to pick the reference location and specify the relative orientation and the scale for the NEZ coordinate system.

If you are using a known local control point and the associated transformation angle and scale values, you can enter this information into your iCMTGIS II or your iGPSGIS II for your newly defined NEZ plane as follows.

From the Main Menu, select Setup then select Coordinate System. Select NEZ , tap the Edit button then enter a name for your new plane.

Tap in the first data field under the GPS Reference section. Enter the LLA coordinates of the reference control point, or tap the Pick button then select the reference point from Map View if that point has been digitized in Map View.

Enter the decimal values for the Angle and Scale fields. Save your settings then return to Map View. When you tap on the map, you will see that the coordinates are now displayed in terms of the NEZ system.