Ubuntu OpenCV not compiling - c++

Question

I'm trying to compile OpenCV 3.2 with contributions with the following commands:
1.
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=/usr/local/ -DOPENCV_EXTRA_MODULES_PATH=/home/matteo/Desktop/Xilinx/OpenCV/source/opencv_contrib/modules/ /home/matteo/Desktop/Xilinx/OpenCV/source/opencv-3.2.0/
2.
make -j7 # runs 7 jobs in parallel
3.
sudo make install
Can you explain why I get
...
........
...........
........................
-- VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file
-- Caffe: NO
-- Protobuf: NO
-- Glog: NO
-- Downloading ...
CMake Error at cmake/OpenCVUtils.cmake:1043 (file):
file DOWNLOAD cannot open file for write.
Call Stack (most recent call first):
../opencv_contrib/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download)
../opencv_contrib/modules/dnn/CMakeLists.txt:5 (include)
CMake Error at cmake/OpenCVUtils.cmake:1047 (message):
Failed to download . Status=
Call Stack (most recent call first):
../opencv_contrib/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download)
../opencv_contrib/modules/dnn/CMakeLists.txt:5 (include)
-- Configuring incomplete, errors occurred!
I'm working with Ubuntu 16.04 . I already had OpenCV on the system: maybe I unistall it in the wrong way? I remember to compile OpenCV 3.2 with the same command used above.

Answer 1

You must have matching versions of the opencv_contrib and the opencv itself.
Under the opencv github, go to the OpenCV releases and download the 3.2.0 (it should be the same in the master branch).
Now, go to https://github.com/opencv/opencv_contrib/releases and download the 3.2.0. Then you will have both versions matching.
After that all the cmake commands found on the README.md at opencv_contrib master branch should work fine.

Answer 2

I get the same error, that exact error, around the protobuf. There's another error on the xfeatures2d module, too, if your delete the dnn modules (so they don't get configured/built). My problem is, I need the "non-free" xfeatures2d module. :(
The problem appears to be in the opencv_contrib, in the DNN and xfeatures2d modules, but I'm not sure how to fix it. the call to ocv_download seems to be having empty inputs, even though the dnn and xfeatures2d cmake files are passing in arguments. I am not even a novice with cmake, so I'm not sure how to troubleshoot further.
I get this error on both Mac configuring for XCode and on Windows configuring for Visual Studio, using the latest version of cmake-gui, 3.8.0-rc3.
EDIT: I think I've found the issue, though. I opened an issue in the opencv_contrib github. There is a call to ocv_download in the dnn and xfeatures2d cmake files that uses FILENAME as the first parameter, but should be using PACKAGE instead. When I changed the parameters to PACKAGE, CMake successfully configured opencv with the opencv_contrib modules.
Hope this helps! :)

Answer 3

You might not use the same version of opencv and opencv_contrib
https://github.com/opencv/opencv_contrib/archive/<version>.zip
https://github.com/opencv/opencv/archive/<version>.zip
like master or 3.2.0

Answer 4

SHORT
You need to have the same version in opencv and opencv_contrib (.../opencv_contrib/modules/... belongs to an independent repo).
Either the same release or the last commit in BOTH repositories.
Check which version you have and move the other. In your case, I guess you have to change the version of opencv_contrib, then move to the release with git or download it from github.
git checkout <number_opencv_version i.e. 3.2.0>
LONG
I guess as Ken Lee, that you do not have the same version in the repositories.
As Matt referenced in the opened issue, there is a problem with the call of ocv_download because the version is not the one that was used when opencv-3.1, therefore it fails because the parameter is not the expected one.
It happens to me when I was using opencv 3.1.0 and the last version of opencv_contrib. You could change the cmake files one by one, but it is easier to take the correct version in each repo.

Answer 5

There is a right conflict in your build folder (may result from your previous sudo make install). I don't remember how I fixed it, but you can try recursively chown to both source and build folders (or chmod to 777).