title: OpenCV C++ Homograpy RANSAC
body: <p>When using <code>findHomography</code> as used the <a href="http://docs.opencv.org/doc/tutorials/features2d/feature_homography/feature_homography.html" rel="nofollow">OpenCV Features2D + Homography Documentation</a>, it calls on <code>CV_RANSAC</code> as its third parameter:</p>
  
  <pre><code>Mat H = findHomography(obj, scene, CV_RANSAC);
  </code></pre>
  
  <p>But in some examples I've seen, you can add in a number after, like this:</p>
  
  <pre><code>Mat H = findHomography(obj, scene, CV_RANSAC, 5);
  </code></pre>
  
  <p>What does this do?</p>
  
  <p>And is there a way of altering <code>CV_RANSAC</code> to perform better, or is it just called like this to do its job as best it can?</p>