Feature matching tutorial compilation problem

edit

Thanks for your reply. I do have searched the forum, but the questions I found were slightly different... Anyway, I have included all of the following:

"<opencv2/core/core.hpp> <opencv2/nonfree/nonfree.hpp> <opencv2/features2d/features2d.hpp> <opencv2/highgui/highgui.hpp> <stdio.h> <iostream>"

but I still get:

/usr/bin/ld: /tmp/ccPbfO0y.o: undefined reference to symbol 'cv::flann::SearchParams::SearchParams(int, float, bool)'

/usr/bin/ld: note: 'cv::flann::SearchParams::SearchParams(int, float, bool)' is defined in DSO /usr/lib/libopencv_flann.so.2.3 so try adding it to the linker command line

/usr/lib/libopencv_flann.so.2.3: could not read symbols: Invalid operation

Then, I included flann.hpp as well and added -lopencv_flann to the build command and I get new errors, such as

feature.cpp:(.text._ZN2cv4SURFD1Ev[cv::SURF::~SURF()]+0x1e): undefined reference to `vtable for cv::SURF'

feature.cpp:(.text._ZN2cv4SURFD1Ev[cv::SURF::~SURF()]+0x6b): undefined reference to `cv::Algorithm::~Algorithm()'

Actually, I just realized that there is no nonfree folder in /usr/include/opencv2. I just tried to find a way of installing it individually, but I couldn't find a way. Hmm.

Hve you also called initModule_nonfree() before calling any SURF methods? And did you link also against nonfree-lib?

Yes I have. I'm reinstalling OpenCV now and making sure nonfree is too. Hopefully that'll fix the issue. [Edit] It's still not working. Here is my current build command:

g++ -Wall -o "feature" "feature.cpp" -I /usr/include/opencv2/ -lopencv_features2d -lopencv_highgui -lopencv_imgproc -lopencv_nonfree -lopencv_flann -lopencv_core

And this is what I get:

/usr/bin/ld: warning: libopencv_core.so.2.4, needed by /usr/local/lib/libopencv_nonfree.so, may conflict with libopencv_core.so.2.3

/usr/bin/ld: /tmp/ccGzJyU9.o: undefined reference to symbol 'cv::Algorithm::~Algorithm()'

/usr/bin/ld: note: 'cv::Algorithm::~Algorithm()' is defined in DSO /usr/local/lib/libopencv_core.so.2.4 so try adding it to the linker command line

Does the order of linked libraries matter?

Now it seems that you have built nonfree w. opencv2.4 but it tries to link it with the core of 2.3. So, you should fix that. Some further notes: I think it should be -I/usr/include (without /opencv2) . For building your program, please have a look at http://answers.opencv.org/question/14611/example-of-makefile/#14649 .

Thanks, I'll have a look at it. Sorry for my double posting (now fixed), there seems to be server problems.

[Edit] I just solved my problem in an unexpected way. I changed my build command to "g++ -Wall -o "feature" "feature.cpp" -I /usr/include/ $(pkg-config --cflags --libs opencv)" and it worked. I'm surprised because I had tried it before and it had failed. I guess reinstalling might have fixed the issue.

Thanks a lot for your help! :)