We have an internally developed document managing tool (in PHP) that serves our purposes well. It has limited support to follow a work-flow for a document, which in our parlance means that it has to follow a chain of approvals after being drawn.
Now, some Autocad drawings are meant to be uploaded (in PDF), having different sizes (however, maybe not that many) and maybe rotations. What we would like would be to write the names of the persons who approve along the chain, but for that we have to detect where it is (as well as the rotation).
My naive idea is to do something similar to QR codes and put 3 black squares on the template so they could be detected, but I have never done anything related to image processing and don't know where to start implementing something like this. I've seen the name OpenCV in other threads, but that would add too much overhead in learning to be practical for such a simple thing, it seems.
Is there any simple way to do this?