Have you ever wondered why perspective drawing using vanishing points works ?

What are these mysterious points that all lines point towards ?, Where are they ?

Well I can do better than just tell you where they are – I can show you what it looks like from there ! All vanishing points are actually in the same place. This is because they are, in fact, none other than our point at infinity.

If we take a simple orthogonal grid like this :

and invert it with respect to a sphere at the centre of the grid, we get something like this :

The video starts inside the central cube of the grid (which has now been turned completely inside out) and moves towards the origin of the inversion sphere. Once there the view rotates and we see that what looks at first strangely similar to a normal perspective view of a straight orthogonal grid, ( compare it with this video of the view inside a normal grid) but if you pause it a moment and take a closer look, you will see that everything is in fact reversed. In a normal perspective all the lines appear to converge as they get farther away. Here they are converging as they get closer to us. This is because we are at the vanishing point!

As the camera turns around a second time it also moves away from the origin and the distortion becomes more apparent.

P.S. I know Googlevideo have had a few server problems recently so here are the same videos on Youtube