how to calculate SIFT/SURF descriptor for 1 point?
I want to calculate SIFT/SURF descriptor for 1 point that I define by myself, how can I do this?
KeyPoint kp;
// init keypoint with values here (coordinates, size, angle..)
vector<KeyPoint> keypoints;
keypoints.push_back(kp);
SurfDescriptorExtractor extractor;
Mat descriptors;
extractor.compute( img, keypoints, descriptors );
So you have to mark the points manually. You could mark a circle, then you would have a size for your feature. And set the angle to 0. But if you want do detect eyes in a picture, this will only work, if some keypoint detector detects a point with the same size and angle.
Yes, you can use any combination of detectors and descriptors. But using different detectors will generally yield different keypoints and thus different descriptors. If you detect features with MSER, you won't get the same keypoints (with the same size/angle) as you marked manually.
Asked: 2012-08-23 07:11:35 -0600
Seen: 3,216 times
Last updated: Aug 23 '12