Keypoint matching using HoG and SIFT I have two images and I've found their keypoints using sift keypoint detector,
Now I have to match their keypoints with HoG features,
I know how to extract HoG description, 
but I dont know how to combine it with SIFT and match the keypoints,
any ideas pls?
I am using opencv and python3
In general, you can use brute force or a smart feature matcher implemented in openCV. 
Another approach is seeing the task as image registration based on extracted features. 

The question may be what is the relation of HoG and SIFT if one image has only HoG and other SIFT or both images have detected both features HoG and SIFT.