title: Install OpenCV 3.0 with extra modules (sift, surf...) for python
body: <p>I tried to install (many many times) OpenCV 3.0 for python with extra package (sift, surf...) but I always fails, I really get stuck.
  I tried in main environment then in virtual ones,</p>
  
  <p>Here is what I did:</p>
  
  <pre><code>cd git
  git clone https://github.com/Itseez/opencv_contrib.git
  cd ..
  wget https://github.com/Itseez/opencv/archive/3.0.0-beta.zip
  unzip 3.0.0-beta.zip
  cd opencv-3.0.0-beta/
  mkdir release
  cd release/
  workon OCR
  cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/home/jbd/src/opencv-3.0.0b -D OPENCV_EXTRA_MODULES_PATH=/home/jbd/git/opencv_contrib/modules -D BUILD_opencv_python3=ON -D PYTHON2_EXECUTABLE=/home/jbd/.virtualenv/OCR/bin/python -D PYTHON_INCLUDE_DIR=/home/jbd/.virtualenv/OCR/include/python2.7 -D PYTHON_LIBRARY=/usr/lib/libpython2.7.so -D PYTHON2_NUMPY_INCLUDE_DIRS=/home/jbd/.virtualenv/OCR/local/lib/python2.7/site-packages/numpy ..
  make -j7
  make install
  cd ~/.virtualenv/OCR/lib/python2.7/site-packages/
  ln -s /home/jbd/src/opencv-3.0.0b/lib/python2.7/site-packages/cv2.so
  </code></pre>
  
  <p>Whatever the way I try to install it, I always get:</p>
  
  <blockquote>
    <p>Traceback (most recent call last):
    File "/home/jbd/git/ocr/test.py", line 10, in 
       sift = cv2.xfeatures2d.SIFT()
    AttributeError: 'module' object has no attribute 'SIFT'</p>
  </blockquote>
  
  <p>with:</p>
  
  <pre><code>import numpy as np
  import cv2
  sift = cv2.xfeatures2d.SIFT()
  </code></pre>
  
  <p>If someone see where I'm wrong...</p>
  
  <p>Thanks a lot</p>