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Orthometric feature heights in TerraFlex add-in Messages in this topic - RSS

Hamish M
Posts: 8

Version 3.7 of the TerraFlex Desktop add-in for ArcMap added support for calculating orthometric feature heights using a geoid model. This topic provides an introduction to how orthometric heights are calculated, where to download geoid models, and how to configure them in your TerraFlex projects published from the TerraFlex add-in for ArcMap

Orthometric Heights
All heights collected in TerraFlex are expressed as heights above the WGS84 ellipsoid (HAE). To convert from HAE to orthometric, or mean-sea-level heights, a geoid model is required which contains the seperation between the ellipsoid and mean sea level for a given point. This article provides a more in-depth look at the history behind mean sea level, ellipsoids and geoids.

Geoid Models
Trimble publishes a library of geoid models and utilities here from which can be downloaded and used with the TerraFlex add-in for ArcMap. Once the geoid file (.GGF) has been downloaded (and unzipped), it needs to be copied into:

if it should be shared with all users on the computer, or to:

if to be used only by a single user

If you have other Trimble office software that uses the Trimble Coordinate System library then geoid files will be automatically load from the library

Configuring a Geoid in your Project
On the last page of the project wizard you will be able to configure how feature heights are calculated when forms are downloaded and saved to the GIS.
If you wish to continue saving features with HAE heights, choose the top option
If you wish apply a fixed geoid separation (rather than using a geoid model), use the second option and define the height in meters
If you wish to use a geoid model to calculate separation use the third option and choose a geoid model from the list

edited by Hamish M on 2/7/2017
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Posts: 4

Have there been any updates to this functionality?
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Posts: 1

We cannot locate any of these file locations, is there another way to install the geoid file?
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Posts: 1

I have version 3.8 of the TerraFlex plugin. Trimble has the geoid files available for download here -
Once downloaded you can move the files to C:\Program Files (x86)\Common Files\Trimble\GeoData Once in the GeoData file I was able to access them in the Geoid separation file drop down in the TerraFlex Plugin for ArcMap.
edited by cmccabe on 11/27/2017
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Posts: 20

cityofcheney wrote:
We cannot locate any of these file locations, is there another way to install the geoid file?

Just build the file structure manually and place the Geoid there (IE create the folders).
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