title: How is a homography calculated?
body: <p>I am having quite a bit of trouble understanding the workings of plane to plane homography. In particular I would like to know how the opencv method works.</p>
  
  <p>Is it like ray tracing? How does a homogeneous coordinate differ from a scale*vector?</p>
  
  <p>Everything I read talks like you already know what they're talking about, so it's hard to grasp!</p>