Get the Image to Camera transformation matrix
Inputs:
* W,H the width and height of the original camera image
* flen the focal length of the camera (as well as the distance between the camera and the image center)
(Note: All angles below move clockwise: NESW, down-forward-up, botton-left to top-right)
* pan is the angle of rotation around Z from North [left-right] corresponds to azimuth: 0<=pan<360
* tilt is the angle of rotation around X from Down [down-up], corresponds to zenith: 0<=tilt<=180
* roll is the angle of rotation around Y clockwise [side-to-side], (depends on horizon line) 0<=roll<360

Outputs:
* T is the PlaneToCamection matrix that gets the points from 2D to 3D

To get 3D points from 2D points: pts3D = T \ ptsIm;
To get 2D points from 3D points: ptsIm = T * pts3D;