Your project area is covered with snow or has a tall vegetation layer and you want to lower your survey objects by a certain distance to compensate for these height offsets. You can do this by applying an offset to your terrain.
All your survey objects (points, polylines and polygons) will follow the terrain automatically when you offset your terrrain. So your survey objects will be at the good level if your offset reflects the thickness of the snow or the grass.
Note that with the 'Offset Terrain', the variability of your terrain within the polygon is preserved. This is not the case when you use the 'Modify Terrain' operation.
Proceed as follows:
Draw a polygon around the area you want to compensate for (Home > Drawing > Polygon).
Make sure this polygon is selected (click on it in the ProjectTree or in the 3D viewport).
- Go to Home > Offset Terrain. Set 'Level' to the elevation difference you want to apply relative to the current situation. For example, if you want the objects to be located 10 cm lower set it to -0.10 m.
Click the 'Offset Terrain' button
The terrain within the selected polygon is moved 10 cm lower. Since the survey objects follow the terrain, they will be placed 10 cm lower as well. The effect is exaggerated in the illustration below for the purpose of clarity.
You can turn the offset off via the ProjectTree. The terrain will come back to its original state and the objects located within the polygon will follow.
Note: If you want to change the elevation of all objects on your terrain select the option 'Offset Entire Terrain' in the 'Offset Terrain' drop-down. You don't need to select a polygon first to perform this operation.