How do I create a heightmap by exact numbers

Hi!
Is there any way to create a landscape with a heightmap where I have an exact height over an area? I can create a mesh in 3DS Max and import it but then I can’t texture it/put folliage on it correctly. Any help is appreciated!

An exact height or a grid of exact heights?

Have a look at L3DT:

I think it can import 3d data from a list of XYZs stored in a text file.

A grid. And thanks! I managed to use L3DT and got the result I wanted =)