cmake is not working in opencv c++ project

问题:

I need your help ! I have this C++ code in this link

[link] https://github.com/royshil/FoodcamClassifier

and I've been trying since two days to compaile it , and I've failed they say that I have to use cmake , I've tried the "GUI version and it gave me errors realted to the cmake itself . so I took the cpp and header files and made a new project but I have now 100 errors related to the opencv library and I swear to god I'm sure of the include folders and the libs of it in my project ! don't know what's the matter with it !

any idea ?

Here's the errors :

'CMake Error: Unable to open cache file for save. C:/Program Files/CMake 2.8/bin/CMakeCache.txt
CMake Error at CMakeLists.txt:4 (FIND_PACKAGE):
  Could not find module FindOpenCV.cmake or a configuration file for package
  OpenCV.

  Adjust CMAKE_MODULE_PATH to find FindOpenCV.cmake or set OpenCV_DIR to the
  directory containing a CMake configuration file for OpenCV.  The file will
  have one of the following names:

    OpenCVConfig.cmake
    opencv-config.cmake



OpenCV_DIR-NOTFOUND
Configuring incomplete, errors occurred!
CMake Error: Unable to open cache file for save. C:/Program Files/CMake 2.8/bin/CMakeCache.txt
CMake Error: : System Error: Permission denied
CMake Error: : System Error: Permission denied '

回答1:

So, this is what fixed this for me.

Firstly, if in doubt - always remember to clear out your CMake "cache" before trying adding some-other path/value/mod. Seems a bit weird I know, but the legacy of previous attempts to fix things may be obsuring the true problem. Simplest way to do this is to nuke your out-of-source "build" directory from orbit (only way to be sure) and try again...

Secondly, and more fundamentally, what is your target compiler & architecture here and what is provided by the version of OpenCV you've downloaded? For example, as of the time of writing the OpenCV 3.1 pre-built installer I downloaded provides ~\build\x64\vc12 & vc14 - which were of course for building against VisualStudio 2012 & 2014.

I was using Mingw and targeting x86 - so I downloaded the source (via github release as a *.zip file) and did these steps from within the \opencv folder:

mkdir build
cd build
cmake -G  "MinGW Makefiles" ..
cmake --build .
cmake --build . --target install

You can of course control the build by various switches and also dictate where an install should go.

Doing the "install" step - by which by default is to copy the final libraries etc. into a folder called "install" - is key as it correctly puts all the resulting libs and files in the right place and includes the magical OpenCVConfig.cmake file at the top.

Thus, I could finally point my project CMakeLists.txt file to resolve OpenCV with:

set("OpenCV_DIR" "C:/Code/opencv/build/install")

find_package( OpenCV REQUIRED )

And, making sure the resulting executable was aware of the *.dll's with:

PATH=%PATH%;C:\Code\opencv\build\install\x86\mingw\bin

回答2:

You're probably gonna have to add the following piece of code in the CMakeLists.txt before the line FIND_PACKAGE(OpenCV Required) (in my case):

SET("OpenCV_DIR" "PATH/TO/CMake/build")

In my installation it solved the problem since the mentioned files are located in the build folder.

回答3:

On Linux I did the following:

$ git clone https://github.com/royshil/FoodcamClassifier.git
$ cd FoodcamClassifier/
$ mkdir build
$ cd build/
$ cmake ../

-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
/usr/local/share/OpenCV
-- Configuring done
-- Generating done
-- Build files have been written to: /home/cog/workspace/opencv/FoodcamClassifier/build

$ make

Scanning dependencies of target build-vocabulary
[  8%] Building CXX object CMakeFiles/build-vocabulary.dir/build_vocabolary.cpp.o
Linking CXX executable build-vocabulary
[  8%] Built target build-vocabulary
Scanning dependencies of target foodcam-predict
[ 16%] Building CXX object CMakeFiles/foodcam-predict.dir/foodcam_predict.cpp.o
[ 25%] Building CXX object CMakeFiles/foodcam-predict.dir/predict_common.cpp.o
Linking CXX executable foodcam-predict
[ 25%] Built target foodcam-predict
Scanning dependencies of target kmeans-trainer
[ 33%] Building CXX object CMakeFiles/kmeans-trainer.dir/kmeans_trainer.cpp.o
Linking CXX executable kmeans-trainer
[ 33%] Built target kmeans-trainer
Scanning dependencies of target make-test-background
[ 41%] Building CXX object CMakeFiles/make-test-background.dir/make_test_background_image.cpp.o
Linking CXX executable make-test-background
[ 41%] Built target make-test-background
Scanning dependencies of target manual-classifier
[ 50%] Building CXX object CMakeFiles/manual-classifier.dir/manual_classifier.cpp.o
Linking CXX executable manual-classifier
[ 50%] Built target manual-classifier
Scanning dependencies of target test-classifiers
[ 58%] Building CXX object CMakeFiles/test-classifiers.dir/test_classifiers.cpp.o
[ 66%] Building CXX object CMakeFiles/test-classifiers.dir/predict_common.cpp.o
Linking CXX executable test-classifiers
[ 66%] Built target test-classifiers
Scanning dependencies of target train-SVM-alone
[ 75%] Building CXX object CMakeFiles/train-SVM-alone.dir/train_SVM_alone.cpp.o
[ 83%] Building CXX object CMakeFiles/train-SVM-alone.dir/training_common.cpp.o
Linking CXX executable train-SVM-alone
[ 83%] Built target train-SVM-alone
Scanning dependencies of target train-bovw
[ 91%] Building CXX object CMakeFiles/train-bovw.dir/train_bovw.cpp.o
[100%] Building CXX object CMakeFiles/train-bovw.dir/training_common.cpp.o
Linking CXX executable train-bovw
[100%] Built target train-bovw

回答4:

For me, on Windows, I received a similar error message when I ran batch scripts with my file editor (Atom) open. Don't think the original question mentioned an OS, and I'm sure my issue was Windows specific.

Though the OS is implied by the URL's in code sample.

If it's not a file-handle/editor issue, it probably is a fie permissions error.