Python Rotate image about camera axis

Question

Say I have an image which I have obtained after applying a homography transformation H to some original image. The original image is not shown. The result of the homography H ap

Answer 1

To apply the homography I would recommend using OpenCV, more specifically the warpPerspective function https://docs.opencv.org/3.0-beta/modules/imgproc/doc/geometric_transformations.html#warpperspective

Because we are talking about a pure rotation, no camera translation, you can indeed produce the image that corresponds to this rotation by just using a homography. But to find the homography parameters as a function of the axis direction and rotation angle, you'll need to know the camera intrinsic parameters, mainly the focal length.

If you had the camera model you could work out the equations, but another way to obtain the homography matrix is just calculating what would be the destination point coordinates after the transform, and then use the findHomography function. Or you can find the matching points, and then you calculate the homography.

If you don't have the camera model and rotation parameters, or matching points in both images, there is nothing you can do, you need any of these to find out the homography. You can try to guess the camera model perhaps. What exactly is the information you have?