title: how to get a bird-eye-view image using opencv without knowing the intrinsic patameters of camera
body: <p>I need to get transform some images to bird-eye-view images, how can i do that without knowing the intrinsic parameters of the camera?  And those images dont have an chessboard in them.</p>
  
  <p>Also, is it feesible that i use an image with chessboard in it to get the intrinsic parameters and then use those parameters to transform those images i need to transform? 
  Or what should I do to get the images transformed?</p>