This command allows you to define the project coordinate system, geoid usage, and scale factors, as well as align on a local coordinate system for GPS. Further discussions on localization are found in Tutorial 2 near the end of the manual.


System Tab

Click Edit Projection List to add to the list and to create user-defined projections. The user may select a predefined or ceate a user defined coordinate projection  system







NAD 27: When selecting this coordinate system, you will also need to specify a state plane zone.  SurvCE will use data files to perform a NADCON datum shift from WGS84 to NAD27 coordinates.  By default, only data files for the continental U.S. are loaded to the data collector.  If you are working outside this region, please load the appropriate files from your CD to the SurvStar\NADConv directory.  NAD27 uses the Clarke 1866 ellipsoid.

NAD 83: When selecting this coordinate system, you will also need to specify a state plane zone.  NAD 83 uses the GRS80 ellipsoid.

UTM: The ellipsoid used in the Universal Transverse Mercator calculation is determined by the Datum selection.  If you choose the option, “WGS 84/Automatic Zone Selection”, the zone is determined by the lat/lon values read in from the receiver.  If you know your UTM zone, you can also select it.  Whenever SurvCE does a reverse calculation (from UTM to WGS84) you will be prompted to enter a zone number.

3TM (Canada): This system is also referred to as “MTM”.  It is a 3 degree zone width Transverse Mercator calculation.  You may select between the Clarke 1866 ellipsoid and the WGS84 ellipsoid.

New Zealand:  You may select between “NZGD2000” and “NZGD49”.  Both use the Transverse Mercator calculation.  NZGD2000 uses the GRS80 ellipsoid.  NZGD49 uses the International 1924 ellipsoid.  You may specify a Meridional Circuit with either datum.  To select the circuit, press the Define button.  You will see a pull-down list with all Meridional Circuits as well as the option to pick None.

RGF 93 (France): This system requires that you have the file named “Predef1.csl” in the SurvStar directory on the data collector.  If this file is not found, please re-install SurvCE.

NTF (France):  This system requires that you have the file named “Predef1.csl” in the SurvStar directory on the data collector.  If this file is not found, please re-install SurvCE. NTF is an approximation of the NTF-GR3DF97A grid transformation.

NTF-GR3DF97A:  This system is a grid transformation that requires the files “Predef1.csl” and “gr3df97a.bin” to be in the SurvStar directory on the data collector. The “Predef1.csl” file is part of the default installation.  You will need to use Data Transfer to copy the “gr3df97a.bin” file from your CD to your data collector.

OSTN02 (UK):  This system is a grid transformation that requires the files “Predef1.csl”, “ostn02_x.bin” and “ostn02_y.bin”.  The “Predef1.csl” file is part of the default installation.  You will need to use Data Transfer to copy the “ostn02_x.bin” and “ostn02_y.bin” files from your CD to your data collector.

RD2000: This is the RD NAP transformation for the Netherlands.  This system is a grid transformation that requires the file “Predef1.csl”, “X2C.grd” and “Y2C.grd”.  The “Predef1.csl” file is part of the default installation.  You will need to use Data Transfer to copy the “X2C.grd” and “Y2C.grd” files from your CD to your data collector.

Denmark 34: Used for all cadastral mapping and for most technical mapping carried out in Denmark. System 34 is a two dimensional - horizontal - coordinate system.  System 34 is based on the National Geodetic Reference Network and is divided into two different zones, one covering Jutland and Fuen, and the other covering Sealand. The island of Bornholm has its own coordinate system called System 45.




New Datum: You may select a predefined Ellipsoid or set your own parameters by typing in a new ellipsoid name and entering values for a and 1/f.  The values for dX, dY, dZ, rot X, rot Y, rot Z and scale are “to WGS84”. 



If the values you have are “from WGS84”, simply reverse the sign of each value (positive becomes negative and vice versa). You will need to save the system to a file.  You may save the system to a “.sys” file or a “.csl” file.  Sys files contain only one system definition.  Csl files contain multiple system definitions. Both files are ASCII text files using OpenGIS WKT (Well Known Text) format.



Load File: To load a user-defined coordinate system from a file, Click under the Edit Projection List button under the SYSTEM tab in Localization. Select Add User Defined and then Load File.   Change the File Type at the top to “.sys” or “.csl” depending on the type of file you are loading.  A “.sys” file will be associated with each job.  You can load the projection last used on a survey job by loading its “.sys” file.  Select your file and hit OK.  If you have selected a ".csl" file, you will be asked to choose from a list of system definitions found in the file.  For the “.csl” type, you may verify that the details of your system have been loaded correctly by clicking the edit option.


TS Tab

The TS tab is where you specify the total station scale and adjustment options.





GPS Tab

The GPS tab is where you define the RTK methods, geoid file, and GPS scale factor.






To match the coordinates of any standard transformation (e.g. UTM, NAD83), the scale factor should be set to 1.0.  When configured to total stations, the Calculate option will calculate the combined grid/elevation factor from any entered coordinatebased on your current state plane zone setting.  This can allow you to go “ground to grid,” to reduce the distance measured by total station to the sea level grid distance of GPS.  If set to a GPS configuration, Calculate becomes Read GPS.  The Read GPS option is grayed out if a multi-point localization is active.  In that case, the scale factor is fixed by the localization itself, and is the inverse of the value appearing in localization, because within Units, we display the “ground to grid” number, whereas in localization, we display the “grid to ground” multiplier.  For base or one-point rover localizations, Read GPS applies.  After converting the LAT/LONG from the GPS to the state plane coordinates and computing the grid and elevation factors, the Scale Factor is applied as the final adjustment to the coordinates. This adjustment is used on the X and Y coordinates, but not Z. In GPS, the Scale Factor is applied by dividing the distance between the coordinate and a base point by the Scale Factor. The coordinate is then set by starting from the base point and moving in the direction to the coordinate for the adjusted distance.


The base point is the first point appearing in the GPS Localization option. If there are no points specified in Localization, then 0,0 is used as base point. The Scale Factor can be entered directly or calculated using the grid factor and elevation for the current position. When using the current position, the program will read the LAT/LONG from the GPS receiver. The scale factor is then calculated as: (State Plane Grid Factor - (Elevation/Earth Radius)).  A scale factor can be used to make grid-to-ground conversions between identical points.  This is useful if you  want to adjust the lesser sea level distances of GPS to the ground (greater) distances measured by total stations whenever you are above sea level.  The grid to ground scale factor is lower at higher elevations because it acts as a divisor (the scale factor is always defined as “ground to grid”).  In summary, when configured to GPS, the scale factor (typically <1) can be used to go “grid to ground” through division, and when configured to total stations, the scale factor (typically <1) can be used to go “ground to grid” through multiplication.  It can also be used for any other scaling purpose desired, but be advised that any scale factor used for GPS is used as a divisor.  Because there are two potential uses of the scale factor (to adjust GPS measurements and to adjust total station measurements), two distinct scale factors are stored and recalled for any job, one for total stations located on the TS tab and one for GPS located on the GPS tab.




How To Use Geoid Files with Carlson SurvCE

  1. Download and/or install either Carlson X-Port or SurvCOM to the desktop computer.
  2. Download and/or install “CarlsonGeoidGrids.exe” to a location on your desktop computer (Typically installed to the “…\Program Files\Carlson X-Port\” directory).
  3. If you have Microsoft ActiveSync already installed on your computer, make sure that it is not currently occupying the COM port.


To do this:

Launch ActiveSync and select Connection Settings from the File menu.

Remove the check box that refers to the port you intend to use with Carlson X-Port (Typically COM1).

Select OK to exit Connection Settings and close ActiveSync.


  1. Connect your handheld device to your desktop computer using a serial cable.
  2. Run Carlson SurvCE on the handheld device and select Data Transfer from the FILE tab.
  3. From within the Data Transfer dialog, select the SurvCADD/Carlson Survey Transfer option.
  4. Leave the data collector waiting for communications as shown by the resulting File Transfer dialog.
  5. Launch either Carlson X-Port or SurvCOM from your desktop computer. If you are using Carlson X-Port, select Carlson SurvCE/SurvStar/G2 from the Tools menu to launch SurvCOM.
  6. From within SurvCOM, and while connected to the handheld computer via a serial cable, you should be able to see the contents of the handheld device on the right and the contents of the desktop computer on the left simultaneously. If you do not see the handheld device on the right, you are not connected.
  7. Select the Geoid icon located at the bottom of the SurvCOM dialog.
  8. From within the Set Geoid Area dialog, verify the path to the geoid files is set to the installed location of these files as defined in step 2 of this document (Typically “…Program Files\Carlson X-Port\”).
  9. Select the desired geoid model to extract an area from.
  10. Key in the approximate latitude and longitude of the center of the area.
  11. Define the grid size for the area you want the model to cover (Supported sizes are 50-250 miles, 80-400 kilometers and 1-5 degrees, however, keep the size 100 miles or smaller for better performance).
  12. Name the geoid model with any name that you want (e.g. "geoid"). You may want to name this file with a logical name for the location of the area for future reference (e.g. "geoid-LA").
  13. Select the OK button to automatically transfer the file to the “…\Survstar\” directory of the handheld device. A copy of the file will also be created on your desktop computer in the currently selected folder.
  14. On the handheld device, go to the FILE tab and select Job Settings, then choose the GPS tab.
  15. Select the Geoid Separation File button and choose the geoid file you created and transferred with SurvCOM.
  16. You have now completed the definition and selection of the geoid file. Select OK to exit the Job Settings dialog.


Points Tab

This tab is where the user adds pairs of positions to create a localization.




Add Method 1--Read GPS: This allows you to collect measurements from the GPS receiver and average as many readings as you choose. Once the readings are complete, the software will present a dialog that displays the range and residuals of the averaged readings.


Add Method 2--Enter Latitude/Longitude: This allows you to hand-enter known geodetic coordinates for the local position. The elevation should be the ellipsoid elevation in the current  job units if a geoid model is not applied. If a geoid model is applied, then the elevation should be the orthometric elevation in the current job units.  This method allows manual entry of a localization file without occupying points in the field.  Note that you do not enter the decimal point for decimal seconds.



If you use manual entry of a localization data set, it is important that you either utilize an existing base GPS receiver with the fixed antenna location that was used to survey the original geodetic positions, or that you set up your base on a known GPS position measured previously using that localization data set.  Good survey practice would include checking into known positions to verify the quality of your hand-entered GPS localization and verifying low residuals in the Localization screen.  With all data pairs used for both horizontal and vertical control (none turned off), the resolutions for this data set will appear.


Add Method 3--From Raw File: This allows you to use a point from the raw data file that has been previously collected via GPS.  This is just like Read from GPS except you are recalling a point previously measured and stored in the raw file.  For this to work, you must have the base antenna in the same position as when the original raw file was collected, or you need to set your base antenna over a known coordinate from the original survey, and enter those original coordinates and the new base antenna height within the command Configure Base.




Note that in this example, it takes three horizontal control points, active “H On = Y” to get horizontal residual results, and four vertical control points, active “V On = Y” to get vertical residual results.  You can employ trial and error to remove different points from consideration both vertically and horizontally and watch the residuals of the remaining control points improve or degrade.  In this way, if you have four or more total control points, you can determine the best combination to use as horizontal and vertical control.


Discussion of Localization Techniques

If you do a base localization by entering Latitude and Longitude or known coordinates on the designated coordinate system, then you do not need to add localization points.  A base localization would put you on grid north and grid scale and would work for any new job where you are not trying to match existing coordinates.  However, any time you are working on a project that has existing coordinates, you will most likely need to do a Localization.  Even if that existing job is supposedly on state plane, UTM or another known coordinate system, the project coordinates often fail to match grid scale and grid north exactly, requiring localization.   When localizing, it is advisable to use at least three points for horizontal control and four points for vertical control, in order to get a measure of residuals (or accuracy).  The program will “best fit” a plane through all activated (H=On and/or V=On) control points.  The residuals are how much each activated point is off of the plane surface.  Because multiple elevation points may create a slightly tilted plane, some surveyors will verify that the vertical control has low residuals and is accurate using multiple vertical control points, then turn off all but one (V=Off) and use only the nearest vertical (elevation) as they progress through the job.


Note:  The Scale Factor chosen in UNITS under Job Settings will cause all GPS measurements to be adjusted by the scale factor.  For GPS, scale factors can only be entered for one-point localizations (base or rover).  For multi-point rover localizations, the scale factor is computed by the localization and fixed.  It appears grayed out under UNITS in Job Settings.  When a scale factor is used for one-point localizations, scaling occurs along the vector outward from the single localization point in the direction of the measured point.  For GPS, the scale factor acts as a divisor.  A scale factor of 0.9 will calculate the measured point 1/0.9 units further away from the single localization point. Therefore, it is recommended that you keep the scale factor set to 1.0.  When configured to total station, the scale factor is sometimes used to go “ground to grid”.  When configured to GPS, the scale factor in is sometimes used to go “grid to ground”, to better match total station scaling.  The scale factor is defined as “ground to grid”.  To go “ground to grid” from high elevations, for example, it would be less than 1.  It would multiply total station measurements and reduce them to grid.  It would divide GPS measurements and expand them to ground.  If your goal is to work on the specified state plane, UTM or other grid coordinate system, and you are planning to use a one-point localization, then the scale factor should be set to 1, unless you are trying to match “ground” coordinates, where the coordinates are “true north” but not “true scale”.  In all other cases, matching ground coordinates with GPS is best accomplished with a multi-point rover-based localization.  The resulting “effective” scale factor multiplier will appear in the localization screen, such as the 0.999779 value shown in the last figure.


After a change in a localization file, any points measured in the field by GPS will be converted from Lat/Long to local coordinates by using the new localization file.  For this reason, it is a good idea to re-convert older GPS measurements to the same, compatible coordinate system by going to Process Raw Data, option Process GPS, within the COGO tab.


Geoid Files

The Geoid file is loaded onto SurvCE using Carlson X-Port.  You first select the area of interest, then X-Port “carves out” the geoid for that area and downloads it to SurvCE.  You set the Geoid file to use in the GPS tab of Job Settings.  The Geoid should be used principally with one-point localizations.  Starting with a known position for the base (or using a one-point rover localization and approximate base position), the program will add or deduct the geoidal separation from the computed Z value on all measurements, and will match more closely to geoid-based surface elevations.  The Geoid can also be used with multiple-point rover localizations, since the added accuracy provided by the geoidal calculation can reduce vertical residuals.  This is true, however, only if the points being matched had Z values that, themselves, considered the geoid.  Since you will get a best-fit plane that minimizes vertical residuals with or without use of the geoid, it is often not used with rover-based localizations.


Changing or Updating the Localization File

There are two ways to change a localization file. One method is to edit an existing file by deleting elements, and the second is to add additional localization points.  In either case, whenever a change in the “.dat” localization file is detected, you are prompted whether you would like to re-process any previously stored GPS points found in the raw file.  The dialog below appears.



If you answer Yes, you will be directed to the Process GPS command found within COGO, Process Raw File.


Recalculating Stored GPS Points

There is no requirement to survey all localization points first, unless you are doing stakeout.  For simple topo or data gathering, you can set up your base, survey in one or two localization points with the rover, then gather data in Store Points as needed.  As you move cross country and encounter another known, or  unexpected, control point, you can localize on it and add it to the list.    The next step would be to verify residuals, and if the results are good, you can reprocess the raw file and keep your entire survey fully updated.  If the residuals are disappointing, you can choose not to include the new point in the localization file.  Either remove it or turn it's H and V components off.  You can also choose Process Raw File to recalculate all GPS measurements at any time.


Including the Base Position in the Localization File

To use the base in the localization, you should configure the base with the Use Local Coordinates option under From Known Position.  Here, you configure the base by entering the local point (5000,5000,100, etc.) and start a new localization file (or use an existing one if it applies).  Then, at your rover, you can add more points to the localization as necessary.


Localization and the Raw File

If the scale for GPS is determined from  the localization, a “GPS Scale” record of 1.0 and a “Localization Scale” equal to the calculated scale appearing in the Localization screen will be written to the RW5 file.  


Using the Localization File to Improve Base Localizations through Logging Static Data

The Localization File (.dat) typically applies to rover-based localizations.  But if you did a Read GPS on your base antenna position and then took GPS shots with no rover localization, and logged static data on the base in the meantime, it is possible to submit that logged information to the OPUS program and obtain an accurate base position.  At this point, it is still possible to recalculate all the field shots taken earlier from the less accurate base.  To do so, follow the procedure outlined below.

  1. Store the Base Point (Reference Tab in the Monitor screen). 
  2. Add a point to the now-empty Localization File.  For the local point, enter the grid system coordinate computed by OPUS or other program.  For the geodetic Lat/Lon point, review the raw file and select the point you stored for the base.
  3. Reprocess the raw file through the localization.  All CRD points should then be relative to the new calculated (eg. OPUS-generated) coordinate.