Opencv 4.6.0 with cuda support were successfully built for both python2.7 and python3.8, but cuda unavailable

Hi I am struggling with activating CUDA (maybe version of pytorch, opencv and python?.)

I am using Jetson Xavier NX developer kit, installed Jetpack 5.0.2 so CUDA 11.4 ver and cuDNN 8.4 ver came together.
To use GPU support I deleted default opencv (4.5.4) of Jetpack and rebuilt 4.6.0 by modifying Cmake -D attribute of JetsonHack(GitHub - jetsonhacks/nano_build_opencv: Build OpenCV on Nvidia Jetson Nano.

Here comes problem - import cv2 in both python version were available, but cv2.cuda.getCudaEnabledDeviceCount() return 0 and torch.cuda.is_available() return False.
I downloaded wheel file in this page (PyTorch for Jetson - #1367 by 19565337738) and followed installation guide. And also I checked proper CUDA version for pytorch 1.11.0 is CUDA 11.4 by torch.version.cuda in python script - so I can be assure version is not cause of my problem.

When I check cv2.getBuildInformation(), python (for build) is printed like this : /usr/bin/python2.7

[attachment for more information - in python3.8 ]

>>> print(cv2.getBuildInformation())

General configuration for OpenCV 4.6.0 =====================================
  Version control:               unknown

  Extra modules:
    Location (extra):            /home/seo/opencv_contrib-4.6.0/modules
    Version control (extra):     unknown

    Timestamp:                   2023-11-01T00:25:15Z
    Host:                        Linux 5.10.104-tegra aarch64
    CMake:                       3.16.3
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/make
    Configuration:               RELEASE

  CPU/HW features:
    Baseline:                    NEON FP16

    Built as dynamic libs?:      YES
    C++ standard:                11
    C++ Compiler:                /usr/bin/c++  (ver 9.4.0)
    C++ flags (Release):         -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /usr/bin/cc
    C flags (Release):           -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):      -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    Linker flags (Debug):        -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    ccache:                      NO
    Precompiled headers:         NO
    Extra dependencies:          m pthread cudart_static -lpthread dl rt nppc nppial nppicc nppidei nppif nppig nppim nppist nppisu nppitc npps cublas cudnn cufft -L/usr/local/cuda-11.4/lib64 -L/usr/lib/aarch64-linux-gnu
    3rdparty dependencies:

  OpenCV modules:
    To be built:                 alphamat aruco barcode bgsegm bioinspired calib3d ccalib core cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv datasets dnn dnn_objdetect dnn_superres dpm face features2d flann freetype fuzzy gapi hdf hfs highgui img_hash imgcodecs imgproc intensity_transform line_descriptor mcc ml objdetect optflow phase_unwrapping photo plot python2 python3 quality rapid reg rgbd saliency sfm shape stereo stitching structured_light superres surface_matching text tracking video videoio videostab viz wechat_qrcode xfeatures2d ximgproc xobjdetect xphoto
    Disabled:                    world
    Disabled by dependency:      -
    Unavailable:                 java julia matlab ovis ts
    Applications:                apps
    Documentation:               NO
    Non-free algorithms:         YES

  GUI:                           QT5
    QT:                          YES (ver 5.12.8 )
      QT OpenGL support:         YES (Qt5::OpenGL 5.12.8)
    OpenGL support:              YES (/usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/
    VTK support:                 YES (ver 6.3.0)

  Media I/O: 
    ZLib:                        /usr/lib/aarch64-linux-gnu/ (ver 1.2.11)
    JPEG:                        /usr/lib/aarch64-linux-gnu/ (ver 80)
    WEBP:                        /usr/lib/aarch64-linux-gnu/ (ver encoder: 0x020e)
    PNG:                         /usr/lib/aarch64-linux-gnu/ (ver 1.6.37)
    TIFF:                        /usr/lib/aarch64-linux-gnu/ (ver 42 / 4.1.0)
    JPEG 2000:                   OpenJPEG (ver 2.3.1)
    OpenEXR:                     /usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/ (ver 2_3)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES
    PFM:                         YES

  Video I/O:
    FFMPEG:                      YES
      avcodec:                   YES (58.54.100)
      avformat:                  YES (58.29.100)
      avutil:                    YES (56.31.100)
      swscale:                   YES (5.5.100)
      avresample:                YES (4.0.0)
    GStreamer:                   YES (1.16.3)
    v4l/v4l2:                    YES (linux/videodev2.h)
    Xine:                        YES (ver 1.2.9)

  Parallel framework:            pthreads

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Lapack:                      YES (/usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/ /usr/lib/aarch64-linux-gnu/
    Eigen:                       YES (ver 3.3.7)
    Custom HAL:                  YES (carotene (ver 0.0.1))
    Protobuf:                    build (3.19.1)

  NVIDIA CUDA:                   YES (ver 11.4, CUFFT CUBLAS FAST_MATH)
    NVIDIA GPU arch:             72
    NVIDIA PTX archs:

  cuDNN:                         YES (ver 8.4.1)

  OpenCL:                        YES (no extra features)
    Include path:                /home/seo/opencv-4.6.0/3rdparty/include/opencl/1.2
    Link libraries:              Dynamic load

  Python 2:
    Interpreter:                 /usr/bin/python2.7 (ver 2.7.18)
    Libraries:                   /usr/lib/aarch64-linux-gnu/ (ver 2.7.18)
    numpy:                       /usr/lib/python2.7/dist-packages/numpy/core/include (ver 1.16.5)
    install path:                lib/python2.7/dist-packages/cv2/python-2.7

  Python 3:
    Interpreter:                 /usr/bin/python3.8 (ver 3.8.10)
    Libraries:                   /usr/lib/aarch64-linux-gnu/ (ver 3.8.10)
    numpy:                       /home/seo/.local/lib/python3.8/site-packages/numpy/core/include (ver 1.24.4)
    install path:                /home/seo/.pyenv/versions/3.8.10/lib/python3.8/site-packages/cv2/python-3.8

  Python (for build):            /usr/bin/python2.7

    ant:                         NO
    JNI:                         NO
    Java wrappers:               NO
    Java tests:                  NO

  Install to:                    /usr/local

>>> cv2.cuda.getCudaEnabledDeviceCount()
>>> torch.cuda.is_available()
>>> exit()

I think this is the main reason because when I try to import torch in python 2.7, it returns

‘no module named torch’

but same action works in python3.8… but still, cv2.cuda.getCudaEnabledDeviceCount() returns 0.

Can anybody answer my question? Is REALLY version of python used for building openCV cause this problem? How can I end this issue? I am struggling with this problem for about 2 weeks so would be very appriciate with your help

In addition, I changed default python version of bash shell to 3.8 but it didn’t change anything, failed to build opencv with python 3.8 . Do you know how to force this?

IF this is not the main reason, installed CUDA itself has problem? This is output of nvcc --version

nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2022 NVIDIA Corporation
Built on Wed_May__4_00:02:26_PDT_2022
Cuda compilation tools, release 11.4, V11.4.239
Build cuda_11.4.r11.4/compiler.31294910_0


Do you run the test within a container?
If yes, please add --system-site-packages to access the host package.

Or you can check our container below which has both OpenCV and PyTorch installed.


@AastaLLL No, I’m not familiar with L4T so I didn’t tried container yet
Is it better than creating virtual environment by conda?


No, just in case you are facing the error due to the virtual environment setting.

For OpenCV, could you try the below script instead?

For PyTorch, we now only provide the package for Python3.
Please try it with Python3 instead.


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