Estimate Homography to do 2D to 3D integration (34): Reading - Ray Tracing & 3D Coordinate from 2D calibrated camera

I. Studying the topic:

   [Ray Tracing]
   - http://www.ics.uci.edu/~gopi/CS211B/RayTracing%20tutorial.pdf
   - Tutorial


   [3D Coordinate from 2D calibrated camera]
   - CALIBRATION OF A 2D-3D – CAMERA SYSTEM 
   - Plane-based calibration of a projector-camera system

   - http://en.wikipedia.org/wiki/3D_pose_estimation
   - Iterative_Closest_Point

   [Calibration Q&A]
   - http://imagelab.ing.unimore.it/visor_test/faq_calibration.txt
   - Geometric Camera Parameters
   - Camera Calibration

II. Draft code for preliminary test:

    - Using the output "Extrinsic Matrix" generated from EPnP to test inverse transformation (...Webcam-Coordinate 3D points back to the corresponding World-Coordinate 3D points). The result shows the position computing by using the Extrinsic Matrix of EPnP is correct.

    - So, from 3D Webcam-Coordinate to the corresponding 3D World-Coordinate is no problem.

    - Next, checking the part of inverse transformation from 2D Webcam-Img-Coordinate to the corresponding 3D Webcam-Coordinate