I don't think i understand copyTo/roi very well because the moment i fiddle with the size of a picture i copy onto another Mat (like picture in picture) i get opencv crashing on me with assertion statements.
What am i doing wrong, or how do i protect against this ? What are the rules?
I understand you can't copy a mat that is bigger then another mat into it. I think i also get crashes when work is done on a empty mat.
I can provide some example code.