The Offset Z tool in Virtual Surveyor allows you to adjust the elevation of the Elevation Terrain, in just a few steps.
- Select the Elevation Terrain item in the Project View.
- Go to the TOOLS tab.
- Set the offset value in the Offset Z box.
- Positive values move the terrain up.
- Negative values move the terrain down.
- Press Enter.
- The Elevation Terrain item is moved up or down according to the offset value setting.
In the example below, the Offset Z value is set to 13.37 feet to make the Elevation Terrain item move up 13.37 feet so the points fit more closely to the surface of the terrain.
Offset Value Information
You can find your Offset Z value in the Selection Box while the Elevation Terrain item is selected.
When to Use the Offset Z Tool
There are a couple of cases where this tool can help you adjust your data or increase the average vertical accuracy of your data if your photogrammetry was processed with an improper datum. However, for most photogrammetry projects, we strongly suggest you apply your controls when processing your projects to get the most accurate vertical data.
Cases where this tool can help:
- Adjust from ellipsoidal/global datums to a local datum by adjusting from one elevation datum to another.
- Adjust to ground control or improving vertical accuracy such as in cases of lidar data by adjusting the Elevation Terrain to independently measured check points.
- A specific scenario typically found in European countries where cross-border measurements are needed to match the elevation datum from one country's vertical datum to another.
Tips and Tricks
- The Check Points tool is often used in conjunction with Offset Z in order to verify the vertical accuracy of your Elevation Terrain.
- You can select multiple Elevation Terrain items in the Project View and apply the Offset Z settings to all of them simultaneously.