I'm trying to compile a sample program after installing Opencv with the command:
g++ hello-world.cpp -o hello-world -I /usr/local/include/opencv -L /usr/local/lib -lm -lcv -lhighgui -lcvaux
however, I'm getting an error that says:
/usr/bin/ld: cannot find -lcv
/usr/bin/ld: cannot find -lhighgui
/uer/bin/ld: cannot find -lcvaux
collect2: ld returned 1 exit status
What do I need to do to correct this?? I installed opencv by downloading the latest stable version and using cmake to create the build files, then ran make install from the command line.
Was there anything I may have missed?
UPDATED-
Better use this command:
g++ opencv.cpp -o opencv -L `pkg-config --cflags --libs opencv`
The pkg-config command will locate the correct include and library for your source code.
For better handling with OpenCV programming go with an IDE like code::block.
Maybe this tutorial will help you in OpenCV programming with code::block:
How to Setup OpenCV for code :: block in Linux and Windows?
Recently I started using OpenCV and I got similar problem and for me this works really well:
-lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_objdetect
Hope it will solve your problem.
You need to add another -L argument specifying the actual location of the OpenCV libraries.
Related
I installed Protobuf in MinGW from the sources on github.
When I try to compile my C++ program I get errors:
CMakeFiles/nxcore_interface.dir/main.cpp.o:main.cpp:(.rdata$.refptr._ZN6google8protobuf8internal13empty_string_E[.refptr._ZN6google8protobuf8internal13empty_string_E]+0x0): undefined reference to `google::protobuf::internal::empty_string_'
collect2: error: ld returned 1 exit status
I found something that indicates the development libs are not present:
Program with protocol-buffers don't compile with MinGW-w64: "undefined reference to google::protobuf:: ..."
I have included the -lprotobuf compiler flag.
After some searching I determined I need to use libprotobuf-dev but I am having trouble locating it.
Does anyone know where to get it, or is something else wrong?
You should compile your application with pkg-config.
g++ my_program.cpp `pkg-config --cflags --libs protobuf`
If you don't have pkg-config you should locate libraries path and set them with -L option. Eg:
g++ my_program.cpp -L/usr/local/protobuf/lib -lprotobuf
I installed GLFW3 and am trying to compile my OpenGL program with the following:
g++ -std=c++11 main.cpp -lGL -lGLEW -lglfw3
But here's the library error I get:
/usr/bin/ld: cannot find -lglfw3
collect2: error: ld returned 1 exit status
I also tried with pkg-config:
g++ `pkg-config --cflags glfw3 glew` -o myprog main.cpp `pkg-config --static --libs glfw3 glew`
it compiles but when I run myprog it says it can't find libglfw.so.3
But it is located in /usr/local/lib
http://www.brandonfoltz.com/2012/12/compile-glfw-on-ubuntu-and-fix-libglfw-so-cannot-open-error/
Ubuntu installs libglfw.so.3 in /usr/local/lib so you have to add this line to /etc/ld.so.conf
I had the same problem.
In my case was usefull following steps:
Download glfw source code
unzip it
cd glfw_folder
cmake . (with dot)
make
sudo make install
To check, copy and paste following command in your console "whereis libglfw3".
you should have output like this one: "libglfw3: /usr/local/lib/libglfw3.a" (or another path after ":").
My config: VAIO Pro 13/Ubuntu 16.04 LTS/ Intel HD4000.
P.S.: Yes, I'd tryed "sudo apt-get install libglfw3" and all dependenses.
I am compiling a C++ application using GNU g++. The project takes advantage of OpenSSL libraries.
Background
On my machine (a 64 bit CentOS quad core) I compile and link my files.
g++ -g -c -L/usr/local/lib/ -L/usr/lib64/
-I/usr/local/include/ -I/usr/local/ssl/include/
-lcrypto mysrc1.cpp mysrc2.cpp mysrc3.cpp
g++ -L/usr/local/lib/ -L/usr/lib64/ -lcrypto
*.o -o ./myapp.out
My application uses function MD5 which is contained in libcrypto.so. As you can see I specify to g++ the dirs where to search using the -L, -I options and which libraries to look for with the -l<lib-name> option. There are some trivial paths like /usr/local/lib which can be omitted of course, but I specified them because the makefile is parametric.
The problem
My problem is that I can successfully compile my stuff (first command), but linking fails (second command):
/usr/bin/ld: cannot find -lcrypto
collect2: ld returned 1 exit status
make: * [cppsims_par] Error 1
But I did check folders and everything... libcrypto.so is inside /usr/lib64/. What is going on?
It may help if you try strace to find why it failed the file lookup
strace -f -e trace=file g++ -L/usr/local/lib/ -L/usr/lib64/ -lcrypto
*.o -o ./myapp.out
I did find the problem and it is related to this question: ld cannot find an existing library
Actually I had no symlink libcrypto.so and the compiler was not able to find the library...
I had related issue, and resolved it after inspecting the trace.
I had
-L<my/path/to/lib> -llib_some_library
when it should have been
-L<my/path/to/lib> -lsome_library
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
OpenCV on ubuntu 11.10
I am having a very hard time trying to install OpenCV on Ubuntu. I believe that I have already installed OpenCV; however, I am trying to compile one of the samples program kalman.cpp with Eclipse, and I am not able to compile it. My problem I believe is linking with the libraries.
I have seen a lot of tutorial, and I do not understand why after installing opencv in my computer, I get the following output after using the command pkg-confi opencv --libs:
manuel#manuel:~$ sudo pkg-config opencv --libs
/usr/local/lib/libopencv_calib3d.so
/usr/local/lib/libopencv_contrib.so /usr/local/lib/libopencv_core.so
/usr/local/lib/libopencv_features2d.so
/usr/local/lib/libopencv_flann.so /usr/local/lib/libopencv_gpu.so
/usr/local/lib/libopencv_highgui.so
/usr/local/lib/libopencv_imgproc.so /usr/local/lib/libopencv_legacy.so
/usr/local/lib/libopencv_ml.so /usr/local/lib/libopencv_nonfree.so
/usr/local/lib/libopencv_objdetect.so
/usr/local/lib/libopencv_photo.so
/usr/local/lib/libopencv_stitching.so /usr/local/lib/libopencv_ts.so
/usr/local/lib/libopencv_video.so
/usr/local/lib/libopencv_videostab.so
Every tutorial out there the libraries appear as:
-L/where/you/have/installed/opencv/lib -lcxcore -lcv -lhighgui -lcvaux
This is really annoying because Eclipse cannot find the library as libopencv_contrib.so. It is waiting for something as -lopencv_contrib
I really appreciate the help. Please let me know what I am doing wrong.
I have never used OpenCV with Eclipse. I basically compile it using gcc or g++ (depending on c or C++) file.
for C file,
$ gcc -ggdb `pkg-config --cflags opencv` -o `basename opencvtest.c .c` opencvtest.c `pkg-config --libs opencv`
for C++ file,
$ g++ -ggdb `pkg-config --cflags opencv` -o `basename opencvtest.cpp .cpp` opencvtest.cpp `pkg-config --libs opencv`
For more information, see http://jayrambhia.wordpress.com/2012/05/08/beginning-opencv/
If you are comfortable with this, I don't think you would need to use Eclipse.
Hope this helps.
To link to a library you need to specify the path to the directory where it is located using the -L /path/to/libraries flag.
You also need the specific libraries you want using -l my_library.
Usually you also need to specify the necessary include paths using -I /path/to/headers
pkg-config can be used as a helper to do this, as it returns the exact parameters you need in order to use a library.
You should rather use it like this:
echo `pkg-config opencv --cflags --libs`
resp.
g++ my_first_opencv_app.cc `pkg-config opencv --cflags --libs`
which on my system evaluates to
g++ my_first_opencv_app.cc -I/usr/include/opencv -lml -lcvaux -lhighgui -lcv -lcxcore
To get it to work with eclipse, you probably need to specify the include path (/usr/local/include/opencv ?), the library path (/usr/local/lib ?) and the libraries you need via some GUI element somewhere in the project settings. You probably shouldn't need pkgconfig then.
I've just updated my system from ubuntu 11.04 to 11.10 and now I can't compile anymore any C program that contain references to OpenCV libraries
I've already tried to reinstall OpenCV (I use the 2.1 version) but I'm stuck with this error:
/tmp/ccArHTZL.o: In function `main':
z.c:(.text+0x59): undefined reference to `cvLoadImage'
z.c:(.text+0xa0): undefined reference to `cvNamedWindow'
z.c:(.text+0xb1): undefined reference to `cvShowImage'
z.c:(.text+0xbb): undefined reference to `cvWaitKey'
z.c:(.text+0xc5): undefined reference to `cvDestroyWindow'
z.c:(.text+0xd1): undefined reference to `cvReleaseImage'
collect2: ld returned 1 exit status
In order to install OpenCV I've always followed this procedure:
$ sudo apt-get install libcv2.1 libcv-dev libcvaux2.1 libcvaux-dev libhighgui2.1
libhighgui-dev opencv-doc python-opencv
$ export LD_LIBRARY_PATH=/home/opencv/lib
$ export PKG_CONFIG_PATH=/home/opencv/lib/pkgconfig
$ pkg-config --cflags opencv
-I/usr/include/opencv
$ pkg-config --libs opencv
-lcxcore -lcv -lhighgui -lcvaux -lml
$ g++ -I/usr/include/opencv -lcxcore -lhighgui -lm hello.c
Anyone can help me?
Why don't you use pkg-config to your favor?
g++ hello.c -o hello `pkg-config --cflags --libs opencv`
I think it is because of some changes from gcc 4.5 to gcc 4.6
Try this command instead (i.e., move the libraries to the end, instead of at the beginning of your command line) -- it works for me:
g++ -I/usr/include/opencv hello.c -lcxcore -lhighgui -lm
I'm still on kubuntu 10.10 so I'm not really familiar how does 11.10 work, but the most common answer to problems with not finding libraries is to use ldconfig with sudo. It'll refresh libraries database. If that doesn't help, look into /usr/lib, /usr/lib64 and /usr/lib32, because its the default place where apt-get throws libraries in. When you find the libraries, change the LD_LIBRARY_PATH so it contains the directory. I don't think that /home/opencv/lib is where they are, but i don't know Your environment
I just upgraded to 11.04 on my laptop and having similar issues. I would try building the latest version of OpenCV (2.3.1) and see if this fixes anything, this seemed to fix quite a few issues for me.
Use the following command, it worked for me:
gcc pkg-config --cflags opencv opencv.c -o open_cv pkg-config --libs opencv