can someone explain me how to do this?
thank you all

Hi and welcome to this forum,

As far as I can tell, this setup is a simple camera which tracks the positions of these piece of papers, and also identifies their colours. The colours are used to activate certain parts of the patch, and their positions are mapped into other parameters (e.g., x-axis mapped into tempo). I am currently working with fiducial markers, which can be used to generate identical results and are very reliable and easy to use: http://reactivision.sourceforge.net/

Here is a very simple example of how it can be implemented:

I hope this helps, take care,
Gilberto

Max Neupert has written some color tracking patches that work quite well. Can't really remember where to find them, but a web search should give results...