title: findHomography, getPerspectiveTransform, & getAffineTransform
body: <p>This question is on the OpenCV functions <code>findHomography</code>, <code>getPerspectiveTransform</code> &amp; <code>getAffineTransform</code></p>
  
  <ol>
  <li><p>What is the difference between <code>findHomography</code> and <code>getPerspectiveTransform</code>?. My understanding from the documentation is that <code>getPerspectiveTransform</code> computes the transform using 4 correspondences (which is the minimum required to compute a homography/perspective transform) where as <code>findHomography</code> computes the transform even if you provide more than 4 correspondencies (presumably using something like a least squares method?).
  Is this correct?
  (In which case the only reason OpenCV still continues to support getPerspectiveTransform should be legacy? )</p></li>
  <li><p>My next concern is that I want to know if there is an equivalent to <code>findHomography</code> for computing an Affine transformation? i.e. a function which uses a least squares or an equivalent robust method to compute and affine transformation.
  According to the documentation <code>getAffineTransform</code> takes in only 3 correspondences (which is the min required to compute an affine transform).</p></li>
  </ol>
  
  <p>Best,</p>