Setting Up Geoids

From ProStar Geocorp


Geoid models can be used to convert elevation measurements received by a GPS into project-specific standards as well as to line up correctly with other survey-grade project data, features and line work. This section outlines how to setup and use Geoids in PointMan. By default, the following Geoid models are available for use out of the box: EGM96, 12A, 12B and Geoid 18.

Setup Procedure

1. Log into PointMan and select the desired Project

2. Tap the menu icon and then tap Settings

3. Next to the Geoid section, tap Edit

4. NOTE: For iOS Only, you must install EGM96 before you can donwload any other Geoids

5. For first time use on iOS, select EGM96 and then tap Download. Tap OK to confirm

6. The icon will change once the Geoid is downloaded (the red part on the icon will disappear)

7. Tap on any other desired Geoid and then tap Download

8. Tap Close

9. In the Geoid dropdown in settings, select the desired Geoid

10. Tap Close to leave PointMan settings and return to the map


Viewing Geoid Data Collected in PointMan

IMPORTANT: Once the Geoid is selected in PointMan settings, the user can collect without any other work. PointMan will automatically perform post-processing to convert elevations to Geoidal heights. PointMan will also save an additional copy of the orgininal altitude. For Android, the original altitude is ellipsoidal. For iOS, the original altitude is Geoidal using Apple's unknown Geoid.

IT IS NOT RECOMMENDED TO USE A GEOID WITH INTERNAL GPS. To use Geoids, pair an external GPS such as Trimble, Emlid or BlueStar.

The following table shows what the user should expect to see in the pedigree (Details) field after recording a feature:

Internal GPS w/ Geoid - Geoid Used
- Elipsoidal Altitude
- Altitude (Geoidal)

- Geoid
- Altitude (Geoidal)

Internal GPS no Geoid - Ellipsoidal Altitude
- Altitude (Orthometric)
- Altitude (Geoidal)
External GPS w/ Geoid - Geoid Used
- Ellipsoidal Altitude
- Altitude (Geoidal)
- Geoid Used
- Ellipsoidal Altitude
- Altitude (Geoidal)
External GPS no Geoid - Ellipsoidal Altitude
- Altitude (Orthometric)
- Ellipsoidal Altitude
- Altitude (Orthometric)