In the link above is a compilation of three demential street art. These drawings trick the viewers into believing that the picture is actually underground or beneath them. This occurs because the drawings trick the viewers depth perception. Depth perception consists of two main cues monocular and binocular cues. The area involved in the street art allusion is the binocular vision area. It allows for 3D vision by forcing the viewer to see two images created from slightly different positions (points of view). Trained artists know how to use specific techniques not only to trick the viewers depth perception, but also to create an amazing spectacle.