The first step in making the project work on Mac OS is to install OpenCV. Fortunately, this is very easy using the brew command. If you develop on Mac OS and do not use it already, you should download it right now. In a nutshell, brew is an alternative package manager that gives you access to many packages (for developers and non-developers) that are not available in the Mac App Store.
You can download and install brew from http://brew.sh/.
In a Terminal, simply type the following command:
brew install opencv
This will download, compile, and install OpenCV on your machine. At the time of writing, the latest OpenCV version available on brew was version 3.2. Once this is done, open filter-plugin-designer.pro and add the following block:
macx { target.path = "$$(QTDIR)/../../QtCreator.app/Contents/PlugIns/designer/" target_lib...