Camera Calibration - Rational Distortion Model

Question

I was looking into the OpenCV 2.2 function cameraCalibration(...) and I noticed a flag CV_CALIB_RATIONAL_MODEL that enables a new radial distortion model supposed to work better with wide-angle lenses:

Where is this model coming from exactly? I read some papers that seemed to be somehow related but the model they employ seems to be quite different from the one implemented by OpenCV.

1. A Rational Function Lens Distortion Model for General Cameras
2. Simultaneous linear estimation of multiple view geometry and lens distortion

Could anyone give me more information about the model opencv exploit and why?

Answer 1

http://opencv-users.1802565.n2.nabble.com/OpenCV-2-2-New-Rational-Distortion-Model-td5807334.html

1. Claus, D. and Fitzgibbon, A.W. A Rational Function Lens Distortion Model for General Cameras Computer Vision and Pattern Recognition (June 2005)

http://www.robots.ox.ac.uk/~dclaus/publications/claus05rf_model.pdf

1. Simultaneous Linear Estimation of Multiple View Geometry and Lens Distortion A. W. Fitzgibbon IEEE Conference on Computer Vision and Pattern Recognition, 2001

http://marcade.robots.ox.ac.uk:8080/~vgg/publications/2001/Fitzgibbon01b/fitzgibbon01b.pdf

Answer 2

Well basically if you don't need GREAT precision (when I mean great I mean 0.003 pixel re-projection error) you can omit that model. It is mainly useful for "fisheye" cameras, where the distortion is huge. A guy in my university is taking his PhD about camera calibration and he says that for normal cameras the precision of the calibration does not increase so much (even decrease because of "dimensionality curse" when calibrating if the images are not enough good or few images used).