title: How to detect the rotation angle of coordinates in an image
body: <p>I am trying to evaluate a simple experiment with a spinning wheel. I have some videos of a spinning wheel (about 60 - too many to process them manually). I want to detect the rotation angle of the wheel in each frame. So my idea was this: After splitting them up into single frames, I ran a feature detection on the image to get the movement of the image features:</p>
  
  <p><img src="https://i.stack.imgur.com/kbGaw.gif" alt="Moving wheel"></p>
  
  <p>Now there are three groups of coordinates:</p>
  
  <ul>
  <li>Those in circular motion (that means: part of the wheel)</li>
  <li>Those in the background (barely moving - but can be used to correct the coordinates of the other ones)</li>
  <li>And those incorrectly detected (e.g. The coordinate on top of the arrow, sliding downwards) - those need to be sorted out.</li>
  </ul>
  
  <p>I want to separate the three groups and detect the angle of rotation of the wheel between the frames, but I don't have an idea how to do this. Are there specific algorithms for detecting rotation around a fixed point?</p>