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The use of a Geoid Model in GPS surveying can greatly increase the precision
of your vertical observations by converting the measured local ellipsoid heights
into orthometric elevations.
Survey Pro can use several different Geoid Models to convert local ellipsoid
heights into elevations. In Alaska, Hawaii, Mexico, and the Caribbean you can use the NGS Geoid99 models or the NGS Geoid96 models.
In the continental USA you can use the new NGS Geoid03 model, or the older NGS Geoid96 or Geoid99 models.
To use a Geoid Model, geoid data files (*.GGF) must be loaded into Survey Pro’s Geodata folder. The map below provides links to download .GGF files for individual states and regions. If you have specific needs for .GGF files of user-configurable regions or different published Geoid models, you should use the Geoid Sub-grid functions in TDS ForeSight DXM or Spectra Precision Survey Office software.
As a service to TDS Survey Pro users, if you live in the continental USA you may use the colored map below to
download a Geoid03 .GGF file for your area; if you live in Alaska or Hawaii, you may download a Geoid99 file.
- Click on your area on the map
- Save the GGF file to your PC
- Copy the file to your data collector's Geodata folder
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