Volume that cuts thru environment

We need a volume that cuts thru the environment (foliage, landscape, destructibles) and that makes invisible their upper parts. On a TBS with high camera placement, the environment often interfere with the combat and makes target and units identification difficult. The map must be cut in levels that sit on on to of each other, like in an old TBS.
The camera slides inside that volume and must see only the environment and units below.