Keypoint response and size, what are they?
What exactly are the keypoint.response and keypoint.size field of a keypoint (in my case, BRISK)?
I found an answer for SURF, but I would like to know what is the meaning for binary keypoint such as BRISK (which is based on AGAST if I remember correctly).
As a reminder, here is the definition that is shown by IntelliSense when typing:
Size: diameter of the meaningful keypoint neighborhood; Response: the response by which the most strong keypoints have been selected. Can be used for further sorting or subsampling
Knowing that, I would be able to assess their use as a way to filter the keypoints.
Be aware that not all keypoint detectors fill those fields. It might be that e.g. AGAST only gives a keypoint size of 1 and a response of 0. Check the code to see if these fields are set up. I only know of ORB,SIFT and SURF for sure that they use these fields (however the meaning in SIFT is differentl afaik since they pack these values somehow if I remember correctly).
Thanks! In the case of BRISK, I get values ranging between 11.2 and 16 for the size and about 31 to 310 for the response.