Compiling using cmake with dependencies installed using macport - opencv

Question

I'm trying to build project that has dependency to OpenCV. I installed Opencv using macports and when I try to build project, cmake gives the following output:
CMake Error at CMakeLists.txt:47 (FIND_PACKAGE):
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV"
provides a separate development package or SDK, be sure it has been
installed.
I searched a little bit about this problem and added the following env. variables to my $HOME/.profile file
export DYLD_LIBRARY_PATH=/opt/local/lib:$DYLD_LIBRARY_PATH
export CMAKE_PREFIX_PATH=/opt/local
without success. I checked and I have all opencv files istalled in /opt/local/lib and /opt/local/include/opencv directories. There is also OpenCVConfig.cmake in the following path:
/opt/local/lib/cmake/OpenCVConfig.cmake
How to make cmake know the path where opencv is installed? Previously I've build OpenCV on my own using cmake and installed into /usr/local and then it worked fine without any other fix. However I had some problems with ffmpeg and right now I switched to using macports.

Answer 1

Another option that works for me was set the env value OpenCV_DIR at the cmake opencv dir:
export OpenCV_DIR=/opt/local/lib/cmake/

Answer 2

macports traditionally installs OpenCV to /opt/local/ instead of the standard /usr/local/.
The solution to your problem is stated at:
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files.
When building your project in the command-line, make sure you execute:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/opt/local/lib/pkgconfig
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/local/lib
And then set the flag CMAKE_PREFIX_PATH for cmake:
cmake -D CMAKE_PREFIX_PATH=/opt/local ../

Answer 3

Not a MACPORT problem, but someone may find this helpful. Followed #hugh-pearse 's and #leszek-hanusz 's answers in this question, with a little tweak. I had installed opencv from ubuntu 12.10 repository (libopencv-)* and had the same problem. Couldn't solve it with export OpenCV_DIR=/usr/share/OpenCV/ (since my OpenCVConfig.cmake whas there). It was solved when I changed some lines on the OpenCVConfig.cmake file:
# ======================================================
# Include directories to add to the user project:
# ======================================================
# Provide the include directories to the caller
#SET(OpenCV_INCLUDE_DIRS "${OpenCV_INSTALL_PATH}/include/opencv;${OpenCV_INSTALL_PATH}/include")
SET(OpenCV_INCLUDE_DIRS "/usr/include/opencv;/usr/include/opencv2")
INCLUDE_DIRECTORIES(${OpenCV_INCLUDE_DIRS})
# ======================================================
# Link directories to add to the user project:
# ======================================================
# Provide the libs directory anyway, it may be needed in some cases.
#SET(OpenCV_LIB_DIR "${OpenCV_INSTALL_PATH}/lib")
SET(OpenCV_LIB_DIR "/usr/lib")
LINK_DIRECTORIES(${OpenCV_LIB_DIR})
And that worked on my Ubuntu 12.10. Remember to add the target_link_libraries(yourprojectname ${OpenCV_LIBS}) in your CMakeLists.txt.

Answer 4

I finally read the header of the OpenCVConfig.cmake file.
It instructs to include these lines to use from an external project:
find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})
target_link_libraries(MY_TARGET_NAME ${OpenCV_LIBS})
(adding include_directories to CMakeLists.txt fixed it for me)

Answer 5

Make sure you have compiled OpenCV, once you compiled, OpenCVConfig.cmake will be generated in build directory.
follow these steps to compile
then , export OpenCV_DIR=<path to build directory with OpenCVConfig.cmake>
It should work now !

Answer 6

I tried all the above ideas in vain.
I eventually found a way to have the compilation work: Besides using #kengregson steps, I simply renamed the folder /usr/local/include/opencv2 so that it is not chosen when compiling my cpp file.

Answer 7

Since I compile my own OpenCV in a multiple-users server, so I can't install the OpenCV libs in /usr/local directly, but in my home folder instead, then exactly the same issue occurs to me.
Below is how I fix it:
Flowing the steps in OpenCV official doc: Using OpenCV with gcc and CMake
Add displayImage test program, and use this CMake file
cmake_minimum_required(VERSION 2.8)
project( DisplayImage )
find_package( OpenCV)
add_executable( DisplayImage DisplayImage.cpp )
target_link_libraries( DisplayImage ${OpenCV_LIBS} )
The same error happened, so add one environment variable in my .tcshrc
setenv OpenCV_DIR "${folder where contains OpenCVConfig.cmake }"
\# mine is:
setenv OpenCV_DIR "~/local/OpenCV2.4.13/share/OpenCV"