title: Camera Intrinsic Matrix for DJI Phantom 4
body: <p>I am trying to estimate a gues for the intrinsic matrix, K, of a DJI Phantom 4 drone. I know that the form of this matrix is:</p>
  
  <p><a href="https://i.stack.imgur.com/mx7XM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mx7XM.png" alt="enter image description here"></a></p>
  
  <p>but i cant seem to get the units right. Looking up the specs at <a href="https://www.dji.com/phantom-4/info#specs" rel="nofollow noreferrer">https://www.dji.com/phantom-4/info#specs</a> I find that the focal length is 8.88 (dosnt say units...) and the image dimensions are 4000x3000. WHat would K look like with these?</p>
  
  <p>*PS, I am scaling down the images so they are smaller. Will this effect the K matrix I should use for openCV?</p>