I think it's a little more complicated than that. I'd be more apt to think it's some custom software/hardware.
Why? There is a constant line of sight with the paint roller. It makes me think that there is a sensor when the roller is being rolled, and that it's also being motion tracked (IR light source/camera maybe). You're then tracking a 2D plane; the wall basically.
With my limited knowledge, street art like this usually comes from people with programming and microcontroller experience. Doesn't seem like an unusual stretch.
Angelo Lorenzo
Fallen Empire - Digital Production Services
RED transcoding, on-set DIT, and RED Epic rental services.
