Selection in 3D Graphics Environments
Christine Albert and Lindsey Press

Continuing along the graphics pipeline, we needed to find the inverse of the projection matrix. By finding the inverse of the projection matrix, we will be moving the object from frustum space back to camera space. Because this inverse is nontrivial, we use a framework in order to find the inverse matrix. Below is the step by step process in finding the inverse of the projection matrix - the framework represents the structure that we followed to calculate the inverse of the projection matrix:

Framework


Projection Matrix


Projection Matrix Inverse




Resources:

http://www.ntu.edu.sg/home/ehchua/programming/opengl/cg_basicstheory.html