The documentation of decomposeHomographyMat proposes a method to invalidate some of the output if additional information is present in the system (needs point sets representing the observed plane in both "before" and "after" images - see the paper linked in the documentation for more details). I have implemented this and it occurred to me that it seems like a piece of functionality that should be present in OpenCV itself.
The way I see it, it could either be a standalone function, or decomposeHomographyMat could be extended (without backwards incompatibility) by adding the point sets as optional extra parameters with empty default values. Perhaps even both (although I can't think of any scenario in which you'd want to use the standalone function call and would not want to use the "integrated" one).
Aside from all that, I'm relatively new to OpenCV so am not entirely sure of all the intricacies of the design philosophies ie. how to integrate this functionality into the framework. What does the OpenCV community think?