Adding modules from opencv_contrib to OpenCV

Question

I'm trying to add the xfeatures2d module from opencv_contrib to an existing OpenCV/Python project.

I've downloaded the latest version of the module from the repo, and built OpenCV again with the following additional params:

OPENCV_EXTRA_MODULES_PATH=/path/to/opencv_contrib-master/modules
BUILD_opencv_xfeatures2d=ON

Excerpt from build log:

-- Installing: /usr/local/lib/python2.7/site-packages/cv2.so
-- Installing: /usr/local/lib/python3.4/site-packages/cv2.so
-- Installing: /usr/local/lib/libopencv_xfeatures2d.3.0.0.dylib

It appears the new module is installed correctly. I'm able to import cv2 in both Python versions. However neither recognise the new features the module is supposed to add.

>>> cv2.SURF()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'SURF'
>>> cv2.xfeatures2d.SURF()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'xfeatures2d'

Answer 1

I encountered this same issue. I'm using python 2.7.6 and OpenCv 3.0 with the additional non-free modules. I do have xfeatures2d present in available modules and can import it, however it was as though xfeatures2d didn't contain SIFT or SURF. No matter how I called them it was the same Error:

"AttributeError: 'module' object has no attribute 'SIFT'

I tried the different name spaces suggested, and only recently noticed this detail and GOT IT WORKING!

$ python

>>>import cv2

>>>help(cv2.xfeatures2d)

You'll notice that it replies that it is now referred to as...

FUNCTIONS

SIFT_create(...)

and

SURF_create(...)

So very simply - the namespace is NOT "cv2.SIFT()" or "cv2.xfeatures2d.SIFT" but rather

cv2.xfeatures2d.SIFT_create()

Please give it a shot!