==== Compiling OpenCV ====

Unfortunately compiling OpenCV on CentOS systems---and by extension RocksOS clusters---is problematic. Several workarounds follow:

Note 1: If you encounter errors in freak.cpp regarding being "unable to find a register to spill" this is caused by a bug in GCC's optimization code. Assuming you can't upgrade GCC easily, then the next best approach is to, after running cmake, edit this file:
YOUR_BUILD_DIR/modules/features2d/CMakeFiles/opencv_features2d.dir/build.make
and ammend the "Building CXX" command for freak.cpp to be:
... GCC $(CXX_DEFINES) $(CXX_FLAGS) -O0 ...

Note 2: If you encounter problems during the testing stage of compiling OpenCV, specifically regarding Python, and Python support isn't required the easiest solution is to disable it completely.  To do so, edit packages/CASCADE-MAKE/OPENCV.sh and add this flag to the cmake command:
-D BUILD_PYTHON_SUPPORT=OFF

Note 3: You may have a similar problem with Java tests at the same stage. Again, if Java support isn't needed, disable it with the cmake flag:
-D BUILD_opencv_java=OFF