Unless I misunderstand what You are trying to do:
You don't need to bother with height.
The x- and z-positions of the objects will be the x- and z-positions of their shadows on the landscape. So the y-vector of that position is the height of the shadow. Or You could just shade its tile.
You don't need to bother with height.
The x- and z-positions of the objects will be the x- and z-positions of their shadows on the landscape. So the y-vector of that position is the height of the shadow. Or You could just shade its tile.