Problems intersecting terrain

[cjrwil]

i am trying to find the volume of a quarry. i have imported lidar data successfully and have triangulated the point cloud to give me a 3d surface.
i then drew a rectangular prism and placed it where i wanted to measure the volume to (ie the top surface intersecting the terrain at the upper lip of the quarry.
i then smoothed the terrain to remove the triangles etc., selected both the rectangular prism and the terrain surface, and slected intersect faces>with model.

after a long amount of time the process ran successfully and a line now seperates the terrain and the upper surface of the box. i exploded the terrain surface and tried to delete the part of the terrain i didnt want however the terrain surface still acts as a whole (as opposed to the rectangle which has a hole removed seperated from the top).

obviously i would like to remove the surplus terrain so i can group the terrain and the upper surface of the box thats left so i can caluclate the volume.

i just cant understand why the terrain is not effected by the intersection process!!!!!!

any help would be greatly appreciated

Chris

[Gaieus]

Intersection always works in the editing context you are in. So while you were "outside" the terrain group, the intersection lines did not affect it as they were also created outside. Now as you have exploded the terrain, try to intersect again (if there is no volume intersection, select all you want to intersect and intersect with selected).

Turn on hidden geometry and only select the faces in the terrain that should be affected - the time needed will be much less this case.