I am working on 3d terrain visualization tool right now. The surface is logically covered with square tiles. This tiling could be visualized as follows:
For some reason I have to know scale of a certain tile in the case of a tilted camera. In the case of a vertical camera (no tilt), all tiles have the same scale which is the camera height divided by its focal length. But if the camera has tilt (i.e. the pitch angle isn't 0) then the scale is changed from tile to tile. Are there any methods to calculate it?