Kokichi Sugihara at Meiji University in Kawasaki, Japan, has been using computer software to bring impossible drawings to life. The video above shows some of the objects he has made moving in ways that appear to defy geometry.
When the models are turned around, however, the trick is revealed: the objects are not what they seem. That’s because we constantly make assumptions about perspective and depth in order to move about in a 3D world, and these models take advantage of those assumptions.
Sugihara used computer software to analyse seemingly impossible drawings and come up with solid shapes that might look like the drawing from one perspective, but not from others.
Also be sure to check out this second 2010 video from Sugihara where he appears to make balls roll *up* ramps.
from New Scientist.