Augmented Reality sandbox

This sandbox seems to have a topographic map projected onto it. This map seems to be created with how the user shifts the sands. I believe there is a program that recognizes the changes in sand and matches topographic data accordingly to the sand, how this is done I don't know. I believe a team of a few people was needed to create this, to do the calculations and create the instruments to make this possible. This seems somewhat complicated as you need to take the whole area of sand into account and the various unpredictable ways someone may shift them around and even how deep or shallow they dig. https://arsandbox.ucdavis.edu/