# Using Open CV with Netbeans 8 on Windows

I have followed the instructions to set up OpenCv from this document and I am trying to use the pre-built libraries with netbeans and the MinGW tool collection.

My simple C++ OpenCV program sees the headers / includes for: opencv2/core/core.hpp and opencv2/highgui/highgui.hpp without any compiler flags.

However I get the following errors from the build:

g++ -m64    -o dist/Debug/MinGW-Windows/opencvtester build/Debug/MinGW-Windows/main.o -LC:\Tools\opencv\build\x64\vc12/temp/lib -lopencv_core2411d -lopencv_highgui2411d -lopencv_legacy2411d -lopencv_ml2411d

C:\Dev\opencvtester/main.cpp:13: undefined reference to cv::Mat::Mat(_IplImage const*, bool)'
C:\Dev\opencvtester/main.cpp:21: undefined reference to cv::namedWindow(std::string const&, int)'
C:\Dev\opencvtester/main.cpp:22: undefined reference to cv::_InputArray::_InputArray(cv::Mat const&)'
C:\Dev\opencvtester/main.cpp:22: undefined reference to cv::imshow(std::string const&, cv::_InputArray const&)'
C:\Dev\opencvtester/main.cpp:24: undefined reference to cv::waitKey(int)'


When I remove the netbeans reference to the link library, I get different errors:

c:/Tools/qt/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/4.8.2/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lopencv_core2411d
c:/Tools/qt/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/4.8.2/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lopencv_highgui2411d
c:/Tools/qt/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/4.8.2/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lopencv_legacy2411d
c:/Tools/qt/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/4.8.2/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lopencv_ml2411d


So I assume the build is finding the library files in opencv/build/x64/vc10/bin but somehow not finding the above references.

I would be grateful if someone could point me at the next steps to take.

Thanks.

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Have you included the headers? I know that under VS you shall include also the ...\opencv\includes\opencv2 folder or under Linux the /usr/local/include/opencv2, so I suppose you shall add the headers folder somewhere, too

( 2015-03-12 07:36:00 -0600 )edit

I have the Includes in the C++ for opencv2/core/core.hpp and opencv2/highgui/highgui.hpp. and for the compile, I include C:/Tools/opencv/build/include. On the link I include ${OPENCV_DIR}/lib where OPENCV_DIR is: C:\Tools\opencv\build\x64\vc12 ( 2015-03-12 07:50:37 -0600 )edit Shouldn't be bin there, ${OPENCV_DIR}/bin`?

( 2015-03-12 08:09:17 -0600 )edit

Thanks for your reply. I removed the \bin and still got the same undefined error messages. I also tried with a filename which doesn't exist and then get the messages described above, e.g. cannot find -lopencv_core2411d.. It appears to be finding the library files but is then unable to find the references within them.

( 2015-03-12 11:38:36 -0600 )edit
2

you can't use the prebuilt vs libs with mingw.

you will have to build the opencv libs using cmake first (resulting in opencv_core2411.a, etc, then try again with those.

( 2015-03-13 04:14:25 -0600 )edit
1

I was gradually coming to that conclusion. I also tried with Visual Studio 2013 and eventually discovered that it also isn't compatible with the released OpenCV libraries, so that requires a build as well.