Learn how to add the new Geoid 18 or any custom user-defined geoid model to the Trimble Coordinate System Manager, which is what Trimble Business Center for its coordinate system definitions.
I've always entered in an approximate height for the job area. Mainly because all the work I do is 3D. Here's what the help guide states. You can see it pertains to 2D coordiantes If a point has no elevation, the Trimble Access software uses the project height in Cogo calculations. If you combine GNSS and 2D conventional observations, set the Project height field to approximate the height of the site. This height is used with 2D points to calculate grid and ellipsoid distances from measured ground distances. In 2D surveys where a projection has been defined, enter a value for the project height that approximates the height of the site. You need this value to reduce measured ground distances to ellipsoid distance, and to compute coordinates.
