Calculate the Affine transformation matrix in image Feature based registration

Question

I have two images, one is the result of applying an affine transform to the other. I can register them using homography by extracting the points using the ORB_create function in OpenCV. However, I want to calculate the Affine matrix needed for this transformation. is there any way of doing it simply by having the two images?

Answer 1

Detect a rotated rectangle and use its corners to get your transformation matrix

Use : getPerspectiveTransform or getAffineTransform

Edit: regarding rotated rectangle detection :

Please check this Opencv tutorial on how to find contours and detect rotated rectangles Creating Bounding rotated boxes and ellipses for contours