title: Undistort kinect depth image cause severe noise
body: <p>I calibrated a kinect RGB camera with chessboard and got its intrinsics parameters and distortion parameters.
  I tried to undistort the Depth image and RGB image with OpenCV provided cvUndistort2 function, but unfortunately severe noise occured in the undistorted depth image.
  Some posts said the noises is included by image smoothing during undistortion. I don't know why , and any tips to get rid of this problem?</p>