OpenCV Q&A Forum - RSS feedhttp://answers.opencv.org/questions/OpenCV answersenCopyright <a href="http://www.opencv.org">OpenCV foundation</a>, 2012-2018.Wed, 02 Mar 2016 19:07:54 -0600Approximation method in cv::undistortPointshttp://answers.opencv.org/question/89082/approximation-method-in-cvundistortpoints/The function `cv::UndistortPoints()`, applies reverse lens distortion to a set of observed point coordinates. The models for lens distortion available in openCV are not invertible, which means an approximation can be made and indeed, from the documentation:
> ...undistort() is an approximate
> iterative algorithm that estimates the
> normalized original point coordinates
> out of the normalized distorted point
> coordinates (“normalized” means that
> the coordinates do not depend on the
> camera matrix).
**My question is therefore:** where can I find information on the approximation method used in `undistortPoints`? What are it's characteristics? How was it derived? Under what conditions is it likely to succeed/fail?
Handling lens distortion well is integral to many 3D Reconstruction applications so it would really be helpful with some clarity here.Wed, 02 Mar 2016 04:01:17 -0600http://answers.opencv.org/question/89082/approximation-method-in-cvundistortpoints/Answer by Tetragramm for <p>The function <code>cv::UndistortPoints()</code>, applies reverse lens distortion to a set of observed point coordinates. The models for lens distortion available in openCV are not invertible, which means an approximation can be made and indeed, from the documentation:</p>
<blockquote>
<p>...undistort() is an approximate
iterative algorithm that estimates the
normalized original point coordinates
out of the normalized distorted point
coordinates (“normalized” means that
the coordinates do not depend on the
camera matrix).</p>
</blockquote>
<p><strong>My question is therefore:</strong> where can I find information on the approximation method used in <code>undistortPoints</code>? What are it's characteristics? How was it derived? Under what conditions is it likely to succeed/fail?</p>
<p>Handling lens distortion well is integral to many 3D Reconstruction applications so it would really be helpful with some clarity here.</p>
http://answers.opencv.org/question/89082/approximation-method-in-cvundistortpoints/?answer=89165#post-id-89165 It seems to be just a normal iteration solver. There's nothing complicated about it. You can see the code [HERE](https://github.com/Itseez/opencv/blob/master/modules/imgproc/src/undistort.cpp#L265).Wed, 02 Mar 2016 19:07:54 -0600http://answers.opencv.org/question/89082/approximation-method-in-cvundistortpoints/?answer=89165#post-id-89165