cv2 3.0.0 cv2.FlannBasedMatcher: flann.knnMatch is throwing cv2 error

Question

I want to use a flann-based matcher in Python as described in http://opencv-python-tutroals.readthedocs.org/en/latest/py_tutorials/py_feature2d/py_matcher/py_matcher.html

Answer 1

If you're on a Mac and using python3, this did it for me instead of building it from github:

brew install opencv3 --with-python3 --with-contrib

and

export PYTHONPATH=$PYTHONPATH:/usr/local/Cellar/opencv3/3.0.0/lib/python3.4/site-packages

replace python3.4 with your version.

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Seems like there's some general problem with the function allocate(). I also had the same problem with BackgroundSubtractorMOG2, beside the FLANN matcher. This fixed both.