I'm working on augmented reality engine and I have a following problem.
I'm tracking a 2D rectangle tracking picture inside an other picture (webcam stream).
I have detected all four 2D corner coordinates for that tracking picture.

Now I need to calculate from the corner coordinates how the original tracker picture has rotated (x-,y-,z-rotations) and zoomed.
Bare in mind that the coordinates doesn't create right angle quadrilateral.
Any ideas how I can do it?
Thanks for any advice.