print(cv2.cuda.getCudaEnabledDeviceCount()) show 0 on jetson nano after compiling opencv-4.1.2 from source

[pandeyshashwat48]

I have compiled opencv-4.1.2 from source using the following commands :
sudo cmake -D CMAKE_BUILD_TYPE=RELEASE
-D WITH_CUDA=ON
-D CUDA_ARCH_PTX=“”
-D CUDA_ARCH_BIN=“5.3,6.2,7.2”
-D WITH_CUBLAS=ON
-D OPENCV_DNN_CUDA=ON
-D ENABLE_FAST_MATH=1
-D CUDA_FAST_MATH=1
-D WITH_LIBV4L=ON
-D BUILD_opencv_python3=ON
-D BUILD_opencv_python2=OFF
-D BUILD_opencv_java=OFF
-D WITH_GSTREAMER=ON
-D WITH_GTK=ON
-D BUILD_TESTS=OFF
-D BUILD_PERF_TESTS=OFF
-D BUILD_EXAMPLES=OFF
-D OPENCV_ENABLE_NONFREE=ON
-D OPENCV_EXTRA_MODULES_PATH=/home/whoami/opencv_contrib/modules …

after installation when I run, print(cv2.cuda.getCudaEnabledDeviceCount()) in python3 I get the output 0, that is quite unusual. As the expected output is 1 to show the 1 cuda enabled device on the nano.

[Honey_Patouceul]

You may try to configure as here :
Compiling OpenCV from Source | OpenCV | RidgeRun.

You may try:

cd <your-opencv-build-directory>

# This would update your current config in CMakeCache.txt and re-generate build files if any
cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/usr/local \
-D OPENCV_GENERATE_PKGCONFIG=ON \
-D BUILD_EXAMPLES=OFF \
-D INSTALL_PYTHON_EXAMPLES=OFF \
-D INSTALL_C_EXAMPLES=OFF \
-D PYTHON_EXECUTABLE=$(which python2) \
-D BUILD_opencv_python2=OFF \
-D PYTHON3_EXECUTABLE=$(which python3) \
-D PYTHON3_INCLUDE_DIR=$(python3 -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())") \
-D PYTHON3_PACKAGES_PATH=$(python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())") \
.

make -j3

sudo make install

Also check if /usr/local/cuda/lib64 is in :

echo $LD_LIBRARY_PATH

if not add it.

[pandeyshashwat48]

Hi, I don’t know much about compilation, but will this solution work if I have installed it already. As in I’ve already ran these commands.

make -j3
sudo make install

also, why make -j3 and not kame -j4… since Jetson has 4 cores, are there any benefits of it.

[pandeyshashwat48]

The complete tutorial helped me solve the problem, thank you so much. Ridge Run’s fork was really working it.