my question is about GPU modules and opencv, is it possible to use this module without a nvidia card, and if yes, could you tell me how ?

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I can answer like you it doesn't matter a question using this tag instead using tag like GPU or CUDA or NVIDIA. It will not be helpful for your answer my friend

Now GPU module in opencv 3.1 is for NVIDIA card and you need to build opencv with CUDA. If you haven't got a NVIDIA card you can still use your GPU if you have GPU compatible with opencl. You can use NVIDIA card with opencl too and without CUDA.

To check if your device is compatible you can do :

cuda::DeviceInfo x;
cout << x.isCompatible();

If you have build opencv without CUDA program throw an exception

So try with opencl

thank you my friend, i don't have a NVIDIA card on my disktop, i have not build the opencv with CUDA, yes you've right the program throw out an embarrassing exception {openCV error: No GPU support (the library is compiled without CUDA support) in EmptyDeviceInfoFuncTable::getDevice, file C:.....\modules\dynamicuda\include\opencv2/dynamicuda/dynamicuda.hpp line 85}

so you can use opencl. With many graphics card like nividia radeon and intel are compatible with opencl. Opencl and Cuda are two differents ways to use GPU card