How install OpenCV_contrib modules after installing opencv - c++

Question

I decided use some extra modules of opencv so i should install OPENCV_CONTRIB firstly,
I Downloaded contrib from this github repo. and extracted the same directory which i installed opencv.
opencv files : /programs/opencv3.0
opencv build: /programs/opencv3.0/build
contrib folder:/programs/opencv3.0/opencv_contrib_master
and then i added extra module path in CMake and while i press Configure button, i got an error:
Error in configuration process, project files may be invalid
and in the bottom window there is this error:
CMake Error at opencv_contrib-master/modules/dnn/cmake/OpenCVFindLibProtobuf.cmake:32 (ocv_download):
Unknown CMake command "ocv_download".
Call Stack (most recent call first):
opencv_contrib-master/modules/dnn/CMakeLists.txt:5 (include)
please help me!

Answer 1

I recommend you to work with the head/master version (or at least sources) in order to keep opencv and opencv contrib synced, and because releases of opencv contrib are not that frequent. If you're planning to keep it automatically updated, you might want to use scripts. In a bash script (update.sh):
#!/bin/bash
cd opencv && git pull
cd ../opencv_contrib && git pull
then with powershell:
$src = "I:/opencv-master/opencv"
$srcextra = "I:/opencv-master/opencv/opencv_contrib"
$build = "I:/opencv-master/build"
$target = "Visual Studio 15 2017 Win64"
bash update.sh
cd $build
rm -Recurse -Force CMake*
cmake -G $target -T v140,host=x64 `
-DOPENCV_ENABLE_NONFREE=1 `
-DOPENCV_EXTRA_MODULES_PATH="../opencv_contrib/modules" `
../opencv | Tee-Object -Variable RESULT
if("$RESULT" -eq 1)
{
"cmake didn't succeed, exiting."
exit
}
msbuild.exe OpenCV.sln /verbosity:m /m
cd ..
then all you have to do is to run the powershell script. Feel free to adjust your cmake configuration with variables -DXXX to match your needs.

Answer 2

You're trying to install contrib modules, which were released in 3.1 and changed a lot in 3.2. (google protobuff for nn is new feature)
So it might be a problem to build it now.
I built 3.2 with contrib on friday and it worked well. Just follow this tutorial very carefully : http://docs.opencv.org/3.2.0/d3/d52/tutorial_windows_install.html