Cmake issue: Could NOT find CUDA: Found unsuitable version "8.0", but required is exact version "9.1" (found /usr/local/cuda-8.0)

[MuziSakura]

As the title, I have installed CUDA 8.0, but does this code must run on CUDA 9.1?

[tnybny]

Your opencv 2.4 is compiled against CUDA-8.0, but you are trying to build this project with CUDA-9.1. This could happen because opencv was built on this machine before CUDA was upgraded to 9.1, which is perfectly acceptable. A fix that worked for me is to specify the CUDA_TOOLKIT_ROOT_DIR cmake variable during the build.
Such as cmake -D CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda-8.0 ...

[fairyzhxz]

You can check your cuda driver version and cuda runtime version. But you should check that you have installed opencv after cuda first.