Using a Geoid GGF File in ArcPad

Using a Geoid GGF File in ArcPad

By Trimble Positions DevTeam

In the latest release of the Trimble Positions ArcPad extension for Windows Mobile, we introduced the ability to calculate mean sea level (MSL) elevations in the field. This was in addition to the functionality that already existed to calculate MSL in the office using the Trimble Positions Desktop add-in. As the release notes indicate, there is no user interface exposed within the extension for specifying the GGF file and it must be done through a registry entry. The way to go about this is by first copying the appropriate Trimble-format geoid file (GGF) to the device and then adding a registry entry that points to it:

[HKEY_CURRENT_USER\Software\Trimble\PositionsArcPadExtension\Geoid]

FullFilePath=<path to the GGF file>

Creating (or editing) a registry entry on Windows Mobile requires some hoop jumping, namely the use of a remote registry editor or a RegEdit-like freeware application. To aid in this configuration step, we have created a very simple application (single .exe file) that can be copied to your mobile device and run locally. Functionality should be self-explanatory:

When you have a geoid file specified, ArcPad will receive only the MSL elevations from the extension.  If you want to confirm the difference between HAE and MSL, you can navigate to the Skyplot screen in the extension and note the HAE value and compare this with what you see on the GNSS overlay in ArcPad. Although you can certainly share the deployed GGF file between the Trimble Positions ArcPad extension and the Trimble Positions Mobile extension, the configuration for the latter must be done through Mobile Project Center as described in the documentation for the ArcGIS for Windows Mobile workflows.

Click here to access Trimble's Geoid Files