Question

I had a generalized question to find out if it was possible or not to do matrix calculations on a rectangle. I have a CvRect that has information stored in it with coordinates and I have a cvMat that has transformational data. What I would like to know is if there was a way to get the Rect to use the matrix data to generate a rotated, skewed, and repositioned rectangle out of it. I’ve searched online, but I was only able to get information on image transforms.

Thanks in advance for the help.

Answer 1

No, this is not possible. cv::Rect is also not capable of that, as it only describes rectangles in a Manhattan world. There is cv::RotatedRect, but this also does not handle skewing.

You can, however, feed the corner points of your rectangle to cv::transform:
http://opencv.itseez.com/modules/core/doc/operations_on_arrays.html?highlight=transform#cv2.transform

You will then obtain four points that are transformed accordingly. Note that there are also more specialized versions of this function, e.g. warpPerspective() and warpAffine().