OpenCV+Darknet

環境: Xubuntu 20.4 (in virtual box)

• OpenCV (3.4.4和4.5.2)
  
  1. Follow this website to install the necessary packages
  2. My setting for CMake

    cmake {...} -D CMAKE_BUILD_TYPE=RELEASE \
    -D CMAKE_INSTALL_PREFIX=/usr/local \
    -D INSTALL_C_EXAMPLES=OFF \
    -D INSTALL_PYTHON_EXAMPLES=ON \
    -D BUILD_EXAMPLES=ON \
    -D WITH_CUDA=OFF (CUDA SDK is not installed) \
    -D WITH_OPENCL=ON \
    -D OPENCV_EXTRA_MODULES_PATH=~/openCV/opencv_contrib/modules\ (your_path)
    -D PYTHON2_EXECUTABLE=\
    -D BUILD_OPENCV_PYTHON3=yes\
    -D PYTHON3_EXECUTABLE=/usr/bin/python3.8\
    -D PYTHON3_INCLUDE_DIR=/usr/include/python3.8\
    -D PYTHON3_INCLUDE_DIR2=/usr/include/python3.8\
    -D PYTHON3_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython3.8.so\ (a soft lint)
    -D PYTHON3_NUMPY_INCLUDE_DIRS=/usr/local/lib/python3.8/dist-packages/numpy/core/include\ (your_path, apt-get install python3-numpy)
    -D PYTHON3_PACKAGES_PATH=/usr/lib/python3/dist-packages 
    -D OPENCV_GENERATE_PKGCONFIG=YES (create the opencv4.pc for opencv version 4.x)
    -D WITH_TENGINE=ON (for Tengine on ARM_64) 
    -D OPENCV_ENABLE_NONFREE:BOOL=ON (such as SURF for Image Stitching) ..
  -----------------------------------------------------------------------------
  -----------------------------------------------------------------------------
  CMAKE要3.19以上(為什麼不會寫在CMakeError.log = =, 後來又有freetype/harfhuzz的問題，先用4.5.3)
    -D BUILD_ANDROID_EXAMPLES=OFF \
    -D ANDROID_NDK=$NDK \
    -D CMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
    -D BUILD_ANDROID_PROJECTS=OFF \
    -D ANDROID_ABI=arm64-v8a \
    -D ANDROID_STL=c++_shared \
    -D ANDROID_NATIVE_API_LEVEL=android-29 
    -D BUILD_SHARED_LIBS=ON \ (build so file)
    -D OpenCV_STATIC=OFF ..
  

  or try to use variable setting

    ...
    ...
    ...
    -D PYTHON3_EXECUTABLE=$(which python3) \
    -D PYTHON_INCLUDE_DIR=$(python3 -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())") \
    -D PYTHON_INCLUDE_DIR2=$(python3 -c "from os.path import dirname; from distutils.sysconfig import get_config_h_filename; print(dirname(get_config_h_filename()))") \
    -D PYTHON_LIBRARY=$(python3 -c "from distutils.sysconfig import get_config_var;from os.path import dirname,join ; print(join(dirname(get_config_var('LIBPC')),get_config_var('LDLIBRARY')))") \
    -D PYTHON3_NUMPY_INCLUDE_DIRS=$(python3 -c "import numpy; print(numpy.get_include())") \
    -D PYTHON3_PACKAGES_PATH=$(python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())")
    
    
    ref: stackoverflow
  

3. Output (Check the Libraries path in Python 3)

...
...
...
...

--   OpenCL:                        YES (no extra features)
--     Include path:                /home/nice/openCV/opencv/3rdparty/include/opencl/1.2
--     Link libraries:              Dynamic load
--
--   Python 3:
--     Interpreter:                 /usr/bin/python3.8 (ver 3.8.5)
--     Libraries:                   /usr/lib/x86_64-linux-gnu/libpython3.8.so
--     numpy:                       /usr/local/lib/python3.8/dist-packages/numpy/core/include (ver 1.20.3)
--     packages path:               /usr/lib/python3/dist-packages
--
--   Python (for build):            /usr/bin/python3.8
--
--   Java:
--     ant:                         NO
--     JNI:                         NO
--     Java wrappers:               NO
--     Java tests:                  NO

4. Compile, reference the website 

5. Troubleshooting:
    a. CL/cl.h: No such file or directory

$ apt-get install opencl-headers
  
ref: Here

    b. linux/videoio.h: No such file

a. $ sudo apt install --reinstall linux-libc-dev

b. $ sudo apt-get install v4l-utils
   $ cd /usr/include/linux
   $ sudo ln -s -f ../libv4l1-videodev.h videodev.h

    c. opencv.pc

$ /usr/local/lib/pkgconfig
a. opencv.pc  (for opencv3.4.2)

b. opencv4.pc (for openc4.x, make a softlink)
   opencv.pc -> opencv4.pc

    d. OpenCV 4.x+ requires enabled C++11 support (ARM version, aarch64)

 error: #error "OpenCV 4.x+ requires enabled C++11 support"

 $ vim Makefile
 ...
 ...
 ...
 CPP=g++ -std=c++11

     e. opencv.pc

$ /usr/local/lib/pkgconfig
a. opencv.pc  (for opencv3.4.2)

b. opencv4.pc (for openc4.x, make a softlink)
   opencv.pc -> opencv4.pc

     f. io.h file not found

CMakeError.log

Determining if the include file io.h exists failed with the following output:
2 Change Dir: /home/ubuntu/object_recognition/opencv/opencv/build_android/CMakeFiles/CMakeTmp
...
...
...
/home/ubuntu/object_recognition/opencv/opencv/build_android/CMakeFiles/CMakeTmp/CheckIncludeFile.c:1:10: fatal error: 'io.h' file not found

注意cmake要求的版本

6. Re-compile:

(in build directory)

a. $ rm -r CMakeCache.txt; 
b. $ Cmake -D ...... (as above)
c. make -j2

7. cv2.so

$ sudo cp /usr/lib/python3/dist-packages/cv2/python-3.8/cv2.cpython-38-x86_64-linux-gnu.so /usr/local/python/cv2/python-3.8/cv2.so
$ sudo ldconfig

8. test

$ python3 -c "import cv2; print(cv2.__version__)"
  
3.4.4

• Darknet
  1. Follow this website to install the necessary packages
  2. Compile with OpenCV (exclude CUDA)

  $ git clone https://github.com/pjreddie/darknet.git
  $ vim Makefile
  $ OPENCV=1
  $ make
  
  ref:
  1. Installing Darknet
  2. 手把手教你用AlexeyAB版Darknet
  

  3. test

  $ wget https://pjreddie.com/media/files/yolov3.weights
  $ ./darknet detect cfg/yolov3.cfg yolov3.weights data/dog.jpg