I followed installation procedure as in How to install OpenCV 3 on Raspbian Jessie. I am successful in entering OpenCV virtual environment. I am unable to compile and install OpenCVV (step 4 in the above link). The reason being is that it's eating up my space in the SD card. I have an 8GB SD card on my Pi. Is it OK to use USB for the same, i.e. compile and build?
P.S : I needed a Pi for OpenCV so that the Pi can detect objects and draw frames using camera module or USB cam.