Ground contour sensor - offroad vehicle

Are there any types of sensors that can read the ground height AHEAD of a vehicle? Looking to develop an active type suspension for a slow moving vehicle. Would like to read the ground height about 20 ft in front of the wheels, and it would need to be able to distiguish between grass and ground. I'm thinking nothing like this exists, but am hoping someone here may have an idea of where to look if it did.

Thanks
Dave

Yes it does, but maybe not specifically for that purpose.
Erwin sick make machine guards, one of their product lines is a 3d laser scanner, using the software that comes with it it gives you a 3d image of the area immediately ahead, you can program it not to respond to moving parts of a machine or exclude certain zones from its field of vision to create a more effective machine guard.
The sensor uses an infra red laser on a 2 axis moving mount.
Depending on your budget one of these might do the trick, for a production run you'd probably want something more bespoke.