matthen:

Walking down a corridor, it’s interesting to see how your image of what’s in front of you shifts with your steps.  Mathematically, your eye is forming a projection of the 3D world onto the 2D retina, and as it moves slightly closer to the walls and the ceiling/floor as you walk, the perspective changes.  This is one example of creating a lower dimensional representation of a higher dimensional reality, another example would be projections of the globe. [more] [code]