Lately I have been experimenting with augmented and mixed reality application development and finally I am figuring a few things out about it. Thanks to a few youtube tutorials I got the transparent shadow plane working after quite a few tries.
Now I just wish, other people besides me could actually have the same experience, watching those pieces. But since the app is custom written in Unity I will not be able to put it out through the official app store.
This is how it works btw (there was a discussion on reddit a few days ago and various ideas rambling about):
After painting on the wall directly, I created some 3D models to match the piece with Unity 3d. With this software and the Vuforia package I built an AR app that runs on my android phone, matching the 3d models on the reference image of the wall.