1 | initial version |
It's not a surprise for me (and even a good think) that you get better results with OpenCV 3.1 compared to 2.4.9 version.
Indeed, there were a pull request in order to fix BRISK by using AGAST detector instead of FAST features as in the original paper, as you can see it here: Fix BRISK detector&descriptor using proper AGAST. #3919.