Convolutional deep neural network module

[ludv1x]

libprotobuf required to sucessfuly buid this module

[alalek]

Hi!

Generally you shouldn't fail whole OpenCV build if some requirements are missing for module (at first it is needed for other users who uses opencv_contrib). In this case you should simply skip module build with optional message.

Use something like this:
https://github.com/Itseez/opencv/blob/48c9c24da6d8d4c432b674eae8808ee717c422c4/modules/cudev/CMakeLists.txt#L1-3

BTW, This patch is rather big, about 5.5Mb, but I believe it is not very critical. Most part is the .caffemodel file.

@vpisarev We can think about installation of the libprotobuf on a some builder to test compilation of this patch (I prefer Linux).

[bhack]

@vpisarev We will have the same problem of the libprotobuf and probably glog gflag dependency on the other DNN project. Then we will put caffe dependency with minimal cmake flag activated in a submodule if you think that will be buildable on buildbot servers. Probably this could help https://github.com/xdbr/cmake-module-submodule.cmake

[bhack]

/cc @mtamburrano @wangyida

[Nerei]

Header for sampe too

[vpisarev]

@ludv1x, could you please also fix the error reported by the doc builder?
http://pullrequest.opencv.org/#/summary/contrib

[Nerei]

👍

Buildbot failures are not related to DNN module

[alalek]

@ludv1x Please recreate PR with "dnn" branch name (same as the extra PR branch name). Also please squash/replace commits into one (102 commits are too much and there are many useless/nonworking intermediate changes)

[alalek]

If you have some problems (there are many "merge" commits from master, squashing will not go well) I prepared a sample squashed commit: c94fdef

You can get it via:

git fetch https://github.com/Itseez/opencv_contrib c94fdefcfff9cc5b8300c49052f0c1eee8896f0b:dnn
git commit --amend # edit commit message
git push -f ...

[Nerei]

@ludv1x The branch should match opencv_extra brach so that buildbot could test them jointly.

[ludv1x]

This PR moves to #362