I want to add a Terrain Perimeter or other terrain objects to my plan, but when I select Terrain and go to Create Terrain Perimeter orone of the other terrain tools, the options are greyed out and I cannot select them.
The Create Terrain Perimeter option will be greyed out and inactive if a Terrain Perimeter already exists in the plan. If there is no Terrain Perimeter in your plan, or if you are on any floor other than that on which the Terrain Perimeter resides, the other terrain tools will be inactive.
To add terrain objects
You must have a Terrain Perimeter in your plan and be on the same floor as the Terrain Perimeter in order to add terrain objects to the plan.
If you do not see a Terrain Perimeter and the Create Terrain Perimeter tool is greyed out , you may have inadvertently placed at Terrain Perimeter on a different floor of you plan.
Zoom out and look at all of the floors of your plan to locate the Terrain Perimeter.
Since your Terrain Perimeter should exist on floor 1, if you find it has been placed on another floor, click on an edge using the Select Objects tool to select it, and delete it either using the Delete edit tool, or the delete key on your keyboard.
You can then return to floor 1 and select Terrain> Create Terrain Perimeter .