title: Finding transformation between two frames
body: <p>I have two consecutive frames from a video feed and I detect the keypoints using the FAST algorithm for both of them. I match the keypoints using the sum of squared difference's method  (SSD).<br>
  So basically I have matched keypoints between the two frames. Now I want to calculate the affine transformation (scale + rotation + translation ) between the two frames from the set of matched keypoints.<br>
  I know how to calculate affine transformation from a pair of two points.<br>
  My question is how can we calculate it for more than two or three points? I know I have to use least median square method but I'm new to this field so I don't know how to use it.<br>
  Can someone please explain this in detail or provide a useful link that does this in a simple way?</p>