I need to calibrate a camera according to soccer field white lines. In order to do so I used Canny for edge detection and HoughLinesP to get the white lines vectors. The location of the camera is not fixed and the picture may contain also the crowed. In this case the crowed may be very noisy for HoughLinesP, thus i thought to extract the ROI of field from the image. Iv'e converted the image to HSV and used inRange on green color. Now, what is the best way to get the ROI?
Link to example for a noisy image - Source and after InRange