Forced Perspective with 3D Graphics

A friend asked me about this problem, on how to calculate the distance an object needs to be from the camera to appear a certain height on the screen.

    Easy Solution:

The solution is simpler when dealing with an object centered in the in the screen where a right angle can be created from the camera to the object.



Fig. 1: right angle triangle diagram.



Solving the triangle in Fig.1:

tan(θ2)=h2d