opencv3 linking from ROS kinetic - opencv

Question

all!
I am trying to use OpenCV library in CLion project, but this is unsuccessful. I have opencv 3.2.0 installed with ROS kinetic at once (I can see it in /opt/ros/kinetic/include/opencv-3.2.0 directory and I can import cv2 by python). But when I use such CMakeLists.txt:
cmake_minimum_required(VERSION 3.6)
project(visual_slam)
set(CMAKE_CXX_STANDARD 11)
set(SOURCE_FILES main.cpp)
set(OpenCV_DIR /opt/ros/kinetic/include/opencv-3.2.0)
include_directories( ${OpenCV_DIR})
add_executable(visual_slam ${SOURCE_FILES})
with the next simple code:
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace cv;
int main()
{
return 0;
}
I get the next error:
CMakeFiles/visual_slam.dir/main.cpp.o: In function cv::String::~String()':
/opt/ros/kinetic/include/opencv-3.2.0/opencv2/core/cvstd.hpp:664: undefined reference tocv::String::deallocate()'
CMakeFiles/visual_slam.dir/main.cpp.o: In function cv::String::operator=(cv::String const&)':
/opt/ros/kinetic/include/opencv-3.2.0/opencv2/core/cvstd.hpp:672: undefined reference tocv::String::deallocate()'
Such error was discussed also in OpenCV linking problems with ROS, but is it really so necessary to uninstall completely and then install again OpenCV? Is there any more quick solution?
Second question, how to correctly add OpenCV from ROS to CMakeLists.txt? Current CMakeLists (look above) does not look like to be flexible. I've already tried to add
find_package(OpenCV 3 REQUIRED)
target_link_libraries(visual_slam ${OpenCV_LIBRARIES} )
but the error is when CMake builds
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided
by "OpenCV" (requested version 3) with any of the following names:
OpenCVConfig.cmake
opencv-config.cmake

Answer 1

The second error you are getting (namely the missing OpenCV.cmake) is actually not only related to the first one (the undefined reference to) but is the cause.
If cmake fails to find the OpenCV module the ${OpenCV_LIBS} won't do a thing meaning that target_link_libraries(visual_slam ${OpenCV_LIBRARIES} ) doesn't link against the libraries your code requires. That said I also believe that it's OpenCV_LIBS instead of OpenCV_LIBRARIES.
You can of course specify the path where the find_package(...) command looks at to find cmake modules (I think it was the CMAKE_FIND_ROOT_PATH variable) or even manually specify the root folder of your OpenCV installation and manually handle all the things that the OpenCV.cmake handles for you.
Last but not least I'm not sure if ROS Kinetic uses the latest OpenCV (what you are using namely the v3.2). You should check that and if different versions are used (very likely), you will have to build all ROS OpenCV-related packages from scratch. You might ask "Why should I do that?". Well, to avoid compatibility issues and various weird errors that may or may not occur (depending on what OpenCV functionality you use) due to version X of OpenCV being used for the binary packages of ROS and version Y present on your system (with X != Y). I had to do that with PCL (Point Cloud Library) once and it took me several days to come to this conclusion since the errors that I was getting were (typical for C++) cryptic as hell. To avoid conflicts make sure that only the one version of OpenCV is present on your system (that is can be found by cmake) that you want to use with your ROS installation. That's also the reason why the ROS binary packages are shipped through the Ubuntu repos using dependencies that are resolved by the package manager (OpenCV, PCL etc.).
PS: Since I haven't used Clion I would also suggest (before doing anything I've mentioned above) to check if it's not some hidden cmake-related setting inside the IDE that screws things up.