about compiling opencv programs outside ROS

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Hi Michael,

Generally the below issues are observed in compiling opencv2.3. As you mentioned these are linking errors. a)

 error while loading shared libraries: libopencv_core.so.2.3: cannot open shared object file:

either your file libopencv_core.so.2.3 is present in /usr/local/lib , and the default opencv directory is /usr/lib so you should change the path of your library. can be done using

export LD_LIBRARY_PATH=/usr/local/lib.

b) or there could be linking problem , which can be resolved by using

ln -s /usr/lib/libopencv_core.so.2.3 /usr/lib/libopencv_core.so.2.2

In your case i observe many such files are missing their links as in the case b. So you may have to link all of them. Before you link make sure what is available in the path and what needs to be added. Check where these files are available in the system. Do the linking after having known this.

And in your compiling you can just use

g++ -o my_example my_example.cpp `pkg-config opencv --cflags --libs`

No need of opencv-2.3.1, unless you have other conflicting version installed.

Hope this helps.

Karthik

Kei is correct. I just ran into this problem too, but instead of using sed, I just created an additional "/usr/lib/pkgconfig/opencv.pc" with the following diff:

12c12
< Libs:  -l${exec_prefix}/lib/libopencv_contrib.so.2.3.1 -l${exec_prefix}/lib/libopencv_legacy.so.2.3.1 -l${exec_prefix}/lib/libopencv_objdetect.so.2.3.1 -l${exec_prefix}/lib/libopencv_calib3d.so.2.3.1 -l${exec_prefix}/lib/libopencv_features2d.so.2.3.1 -l${exec_prefix}/lib/libopencv_video.so.2.3.1 -l${exec_prefix}/lib/libopencv_highgui.so.2.3.1 -l${exec_prefix}/lib/libopencv_ml.so.2.3.1 -l${exec_prefix}/lib/libopencv_imgproc.so.2.3.1 -l${exec_prefix}/lib/libopencv_flann.so.2.3.1 -l${exec_prefix}/lib/libopencv_core.so.2.3.1
---
> Libs: -L${libdir} -lopencv_contrib -lopencv_legacy -lopencv_objdetect -lopencv_calib3d -lopencv_features2d -lopencv_video -lopencv_highgui -lopencv_ml -lopencv_imgproc -lopencv_flann -lopencv_core

or if you just want the contents of the file:

# Package Information for pkg-config
prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir_old=${prefix}/include/opencv-2.3.1/opencv
includedir_new=${prefix}/include/opencv-2.3.1

Name: OpenCV
Description: Open Source Computer Vision Library
Version: 2.3.1
Libs: -L${libdir} -lopencv_contrib -lopencv_legacy -lopencv_objdetect -lopencv_calib3d -lopencv_features2d -lopencv_video -lopencv_highgui -lopencv_ml -lopencv_imgproc -lopencv_flann -lopencv_core
Cflags: -I${includedir_old} -I${includedir_new}