Virtual Surveyor can help you align your photogrammetry outputs with your elevation datum.
The proper elevation datum needs to be set up in your photogrammetry process, which needs to be done before you start working in Virtual Surveyor. Typically, your image processing software only exports the Ellipsoidal height unless you use Ground Control Points (GCPs) or adjust the 3D model to a global or local geoid model.
Virtual Surveyor's Offset Z tool provides a quick and easy way to adjust your data to local heights.
In the example below, the Elevation Terrain is set to the drone's photogrammetric ellipsoidal height. By comparing the drone ellipsoidal height information with the vertical datum we're currently using, you can see that it is 13.37 feet below the vertical geoid Z height.
Steps to Adjust the Elevation Datum
To adjust the drone's ellipsoidal height to the vertical geoid Z height:
- Select your Elevation Terrain item and click on the TOOLS tab.
- Set your Offset Z value to 13.37 ft.
- This moves the Elevation Terrain item up 13.37 ft, and the points now fit better to the surface of the terrain.