The software knows the size each square should be when placed at a certain distance from the camera. By comparing this base-line size to the size in-picture, depth can be determined. And by considering the deformity of the squares the software can determine the angle of the cube relative to the camera. The easy part is directional markers. That’s taken care of by the “icons” on the face of each cube. The thick squares on each face take care of the rest. Its still a nice trick, but nothing special.”]
Source: https://gizmodo.com/cyber-figure-alice-creates-interactive-virtual-peepshow-5027038