Summary to install opencv in virtualenv

1. Install opencv-python in unbuntu

2. Copy cv2.xxx.so into venv->python->packages

you may copy from opencv cmake source:

$ cp /usr/lib/python2.7/dist-packages/cv2.x86_64-linux-gnu.so ~/py_venv/py2.7venv/lib/python2.7/site-packages

or, you may copy from pip-installed opencv-python packages

$ cp -r /home/robin/.local/lib/python3.5/site-packages/cv2 ~/py_venv/py3.5venv/lib/python3.5/site-packages/

(if you don't know where is the pip-installed opencv-python packages, you can run:

python -c "import cv2; print('cv2.__version__'); print('cv2.__file__')"

to check the location.)

3. Check opencv under venv

$ source ~/py_venv/py2.7venv/bin/activate
(py2.7venv) $ python -c "import cv2; cv2.namedWindow('test'); cv2.waitKey(0); cv2.destroyAllWindows()"