Estimate Homography to do 2D to 3D integration (36): Reading - Ray Tracing & 3D Coordinate from 2D calibrated camera

I. Modified code:

   - To set up a range for searching, instead of finding upper_bound and lower_bound of fZ in the World-Coord-Sys, using a method like "Bag-of-word strategy"
  
   - Trying to decrease the complexity in finding the corresponding fZ in the Webcam-Coord-Sys

   - Trying to think a better way to compute the similarity in order to find the most similar 3D point in the World-Coord-Sys