CMake Error: Variables are set to NOTFOUND

Question

I installed cuda first using cuda-repo-ubuntu1604-9-0-local_9.0.176-1_amd64.deb. Now I\'m trying to install OpenCV 3.3.0 But i\'m getting CMake Err

Answer 1

This worked for me on Ubuntu 18.04 with OpenCV 4.2.0 and CUDA 10.0

Apparently, I was missing symbolic links to these libraries, so CMake couldn't locate them:

sudo ln -s /usr/lib/x86_64-linux-gnu/libnppc.so.9.1 /usr/lib/x86_64-linux-gnu/libnppc.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppial.so.9.1 /usr/lib/x86_64-linux-gnu/libnppial.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppicc.so.9.1 /usr/lib/x86_64-linux-gnu/libnppicc.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppicom.so.9.1 /usr/lib/x86_64-linux-gnu/libnppicom.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppidei.so.9.1 /usr/lib/x86_64-linux-gnu/libnppidei.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppif.so.9.1 /usr/lib/x86_64-linux-gnu/libnppif.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppig.so.9.1 /usr/lib/x86_64-linux-gnu/libnppig.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppim.so.9.1 /usr/lib/x86_64-linux-gnu/libnppim.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppist.so.9.1 /usr/lib/x86_64-linux-gnu/libnppist.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppisu.so.9.1 /usr/lib/x86_64-linux-gnu/libnppisu.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnppitc.so.9.1 /usr/lib/x86_64-linux-gnu/libnppitc.so
sudo ln -s /usr/lib/x86_64-linux-gnu/libnpps.so.9.1 /usr/lib/x86_64-linux-gnu/libnpps.so

Update: Although the above command allowed me to run CMake successfully, I still wasn't able to build. sudo apt-get install nvidia-cuda-toolkit did the trick.