Rotation Estimation between two images

Question

I want to get the rotation between two images taken from the same camera (known intrinsic). I have a nearly perfect pure rotation!

I use findhomography but if there is a little translation movement I get four results. Is there a way to force the homography that it assumes it is a pure rotation?

EDIT: Picture sample: the camera is rotating

Answer 1

You can decrease the dimension of the problem a bit by using cv::estimateRigidTransform and passing false for fullAffine argument. This will make it translation, rotation, and uniform scaling but there is is not pure rotation method in OpenCV.