does opencl require any other optional tags to work?
If I compiled the opencv3.1 library without opengl support, is opencl through the TAPI still able to use the GPU accelerated code? If I have an NVIDIA based card do I need cuda compiled in to see the benefits?
About NVIDIA card and opencl you will see benefits without CUDA if you compile opencv with opencl only.
About opengl support in opencv I think that when OPEN_GL is on in CMake it means you will build specific function and librairies inside opencv
of course resource are limited when you will ask an opencv function using opencl and you want to display 3D graphics using opengl memory and gpu will be shared...