title: view mapping between two images taken from same cameras of same scene using homography in open CV, except the camera positions are not parallel
body: <p>I am trying to understand mapping points between two images of same scene except the camera positions are different. say like this <a href="https://i.stack.imgur.com/5ETyC.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5ETyC.jpg" alt="approximate camera position" /></a> apologies for the rough sketch and the hand-writing.  Sample image taken from cam1 <a href="https://i.stack.imgur.com/0wWpS.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0wWpS.jpg" alt="camera1 capture" /></a> and Sample image taken from cam2 <a href="https://i.stack.imgur.com/GLell.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GLell.jpg" alt="camera2 capture" /></a>. Trying to map between these two images. since the two cameras used are same(logitech camera). I assume camera calibration isn't required. So with the help of SIFT descriptors and feature matching, using the good matches from the images as inputs to Homography with RANSAC. I get 3*3 matrix. To verify the view mapping. I select few objects(say bins in the image) in cam1 image and try to map the same object in cam2 image using 3 * 3 matrix by using warp_perspective, but the outputs aren't good. say something like this <a href="https://i.stack.imgur.com/4BPIZ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4BPIZ.jpg" alt="view map output" /></a>  had selected top left and bottom right of the objects in cam1 image(i.e. bins) and trying to draw a bounding box for the desired object in cam2 image.
  But as visible in the view map output image the bounding boxes aren't proper to the bins.</p>
  <p>Wanted to understand, where am i going wrong. Is it the camera positions affecting, and this shouldn't be used for homography or have to use multiple homographies or  have to get to know the translation between the camera positions. very confused. Thank you.</p>