title: Film coordinate to world coordinate
body: <p>I am working on building 3D point cloud from features matching using OpenCV3.1 and OpenGL.</p>
  
  <p>I have implemented 1) Camera Calibration (Hence I am having Intrinsic Matrix of the camera) 2) Feature extraction( Hence I have 2D points in Pixel Coordinates).
  I was going through few websites but generally all have suggested the flow for converting 3D object points to pixel points but I am doing completely backword projection. Here is the <a href="http://www.cse.psu.edu/~rtc12/CSE486/lecture12_6pp.pdf" rel="nofollow noreferrer">ppt</a> that explains it well. </p>
  
  <p>I have implemented film coordinates(u,v) from pixel coordinates(x,y)(With the help of intrisic matrix). Can anyone shed the light on how I can render "Z" of camera coordinate(X,Y,Z) from the film coordinate(x,y).</p>
  
  <p>Please guide me on how I can utilize functions for the desired goal in OpenCV like solvePnP, recoverPose, findFundamentalMat, findEssentialMat. </p>