can HOG feature detection be used to keypoint matching?

I see HOG is often used with SVM for target detection, can it be used in matching keypoints in tw开发者_开发技巧o images?

and btw, where could I find OpenCV sample of using HOGDescriptor?

HOG can be used without SVM for feature matching. just choose some points ( edge, for example ) and calculate the feature of HOG inside ROI with those points centered. HOGDescriptor seems only for GPU programming. I created Descriptor for HOG as a Mat in openCV and it also works for OpenCV matching functions.

If you are working with images you can use SIFT/SURF with SVM. There is nothing that stops you from using HOG for keypoint matching, but bear in mind that the effectiveness depends on discrimination power and robustness of the descriptor.

Edit: My bad in understanding when I originally mentioned HOG being for video only. Somehow I was thinking about histogram of optical flow vectors which is very effective for video activity description.

Edit 2 [Oct '12]: I now suggest people to try ORB or BRISK for those looking for license friendly descriptors that are fast and quite effective for keypoint matching.