OpenCV ORB detector finds very few keypoints

Question

I\'m trying to use the ORB keypoint detector and it seems to be returning much fewer points than the SIFT detector and the FAST detector.

This image shows the keypo

Answer 1

Increasing nfeatures increases the number of detected corners. The type of keypoint extractor seems irrelevant. I'm not sure how this parameter is passed to FAST or Harris but it seems to work.

orb = cv2.ORB_create(scoreType=cv2.ORB_FAST_SCORE)

orb = cv2.ORB_create(nfeatures=100000, scoreType=cv2.ORB_FAST_SCORE)