Question

I’m a beginner in computer vision. I have a question about detection and tracking. I want to detect the white rectangle in the image below, to determine the interesting area and to detect the contour of the red markers.

But I don’t want to make use of color information to detect the markers.

Can anyone give me suggestions on how to do this?

Answer 1

You can find the contours with CvFindContours and use CvApproxPoly() to find the rectangle. You can find a good example of how to use this function to find rectangles here and adapt it to your situation. To find the circles I would advise to do something with the ratio between the arcLength and the area of the contours you find as for circles this ratio is very specific. To find the arcLength use cvArcLength(CvSeq* c) to find the area use cvContourArea(CvSeq* c) while going through the contours in a for loop.