Determine the area of the intersection of two rectangles

Question

I have two rectangles, each identified by a set of four coordinates. I've read up on how to see whether they intersect, but how can I calculate the area of the intersection? The rectangles are not axis-aligned.

Is there an OpenCV function for this? I was told there was, but I fail to find it.

Answer 1

Treat your rectangles as general polygons, and decompose the problem into two steps:

• compute the intersection of the two polygons, which itself is a polygon (or is empty);
• compute the area of the resulting polygon.

There's plenty of literature on the Web for both problems.

I don't know anything about OpenCV so can't give any advice there.