1 Variable 'exec_prefix' not defined in '/usr/local/lib/pkgconfig/opencv.pc'
After a detailed search on the Internet, the configuration information file opencv.pc is missing or there is a problem with the content in the file, so the solution is to add this file and import it into the environment variable
1.1 Create opencv.pc file
sudo touch opencv.pc
Because you do not have permission to modify, first modify the permissions of the file
Change file permissions
Enter the terminal in the same directory:
sudo chmod 777 opencv.pc
Copy the following content to opencv.pc
prefix=/usr/local
exec_prefix=${prefix}
includedir=${prefix}/include
libdir=${exec_prefix}/lib
Name: opencv
Description: The opencv library
Version:4.1.1
#This 4.1.1 is the OpenCV version and needs to be changed to your own version
Cflags: -I${includedir}/opencv4
Libs: -L${libdir} -lopencv_shape -lopencv_stitching -lopencv_objdetect -lopencv_superres -lopencv_videostab -lopencv_calib3d -lopencv_features2d -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_video -lopencv_photo -lopencv_ml -lopencv_imgproc -lopencv_flann -lopencv_core
~
1.2 Save and exit, and then import the file to the environment variable: (Enter the environment variable method: gedit ~/.bashrc)
export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
Then look at the source:
source ~/.bashrc
Finally, enter the following to see the version of OpenCV
pkg-config --modversion opencv
2 Problems encountered when recording catkin_make
at /opt/ros/noetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV"
provides a separate development package or SDK, be sure it has been
installed.
Invoking "make cmake_check_build_system" failed
Solution:
Problems encountered when recording catkin_make
E: Unable to locate package ros-kinetic-driver-base
Problems encountered in downloading controls, to install your own version controls:
My system is Ubuntu20.04 and noteic version control needs to be installed:
sudo apt-get install ros-noetic-driver-base
sudo apt-get install ros-noetic-gazebo-ros-control
sudo apt-get install ros-noetic-effort-controllers
sudo apt-get install ros-noetic-joint-state-controller
sudo apt-get install ros-noetic-ackermann-msgs
sudo apt-get install ros-noetic-global-planner
sudo apt-get install ros-noetic-teb-local-planner
3 记录catkin_make时遇到的问题
Invoking "cmake" failed
解决方法：
pip install -U rosdep rosinstall_generator wstool rosinstall six vcstools -i https://pypi.douban.com/simple
或catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3
参考文章链接：https://blog.csdn.net/qq_44920947/article/details/123300367
没有成功尝试别的方法：
本文链接：https://blog.csdn.net/qq_39437730/article/details/118272390
没有解决换一个方法：
总结了常见问题
ubuntu 20.04 安装 ROS noetic，catkin_make报错python版本不一致，处理办法
catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3
cmake找不到opencv解决
本文链接：https://blog.csdn.net/jacke121/article/details/112827563
source ~/catkin_ws/devel/setup.bash
· 1
export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:~/catkin_ws/
自建引用包报错：CMake Error at /opt/ros/melodic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
解决方法：
1.将opencv安装目录添加到CMAKE_PREFIX_PATH
例如，按照错误信息指示，在CMakeLists.txt中加入一行list，路径要改成自己的opencv安装路径。
list(APPEND CMAKE_PREFIX_PATH "/home/xiaoming/opencv4.5.5/")
find_package(OpenCV REQUIRED)
4 运行catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3时
出现：The specified source space "/home/sxj/src" does not exist
回到catkin_ws工作空间下进行编译
或者可能曾经误在home下catkin init过,系统误认为home是工作空间
home下ctrl+h显示隐藏文件
删除文件夹.catkin_tools
