I have installed opencv in Ubuntu 20.04 following the instructions in OpenCV Installation in Linux. As per the instructions, sudo make install copies all the .so files to /usr/local/lib.
However, when compiling a program, using the command g++ --std c++17 -g opencv/Basic.cpp -o output -I/usr/local/include/opencv4 -L/usr/local/lib/ -llibopencv_calib3d -llibopencv_core -llibopencv_dnn -llibopencv_features2d -llibopencv_flann -llibopencv_highgui -llibopencv_imgcodecs -llibopencv_imgproc -llibopencv_ml -llibopencv_objdetect -llibopencv_photo -llibopencv_stitching -llibopencv_video -llibopencv_videoio I get the following error.
/usr/bin/ld: cannot find -llibopencv_calib3d /usr/bin/ld: cannot find -llibopencv_core /usr/bin/ld: cannot find -llibopencv_dnn /usr/bin/ld: cannot find -llibopencv_features2d /usr/bin/ld: cannot find -llibopencv_flann /usr/bin/ld: cannot find -llibopencv_highgui /usr/bin/ld: cannot find -llibopencv_imgcodecs /usr/bin/ld: cannot find -llibopencv_imgproc /usr/bin/ld: cannot find -llibopencv_ml /usr/bin/ld: cannot find -llibopencv_objdetect /usr/bin/ld: cannot find -llibopencv_photo /usr/bin/ld: cannot find -llibopencv_stitching /usr/bin/ld: cannot find -llibopencv_video /usr/bin/ld: cannot find -llibopencv_videoio collect2: error: ld returned 1 exit status
I have also added a .conf file in /etc/ld.so.conf.d/opencv.conf with the line /usr/local/lib/ and issued the command sudo ldconfig. However, the issue remains.
I’d be grateful for any ideas or suggestions to resolve this issue.
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Answer
-llibopencv_calib3d
make it
-lopencv_calib3d
etc. the lib part in front of it is simply wrong