Fractal images

No problem, Rich. I don't know them all either.

I discovered this effect independently when I was a very young lad. I just stared at bathroom floors with small tiles, and crossed my eyes by one tile width, and lo, and behold the floor took on a third dimension, with the grout seeming to be as much as a foot above the floor. Every visit to a new bathroom was an adventure in 3D.

Wonder why it didn't do the opposite and make the blocks appear above the grout?
Thanks,
barondla

Tried it with this on my monitor:

I got a lock, albeit overlapped, but no depth effects.

This locked properly but still no depth effects.

No tiles in my cabin ...

This one shows an easily identifiable 3D effect in the different depths at which the different colored squares are positioned.

The power of depth separation differs from one person to another. There are medical tests specifically designed to determine these differences.

The grout and the edges of the tiles are where most of the differences in edges are. It is those differences that create the illusion of depth.

I see depth here. All the tiles seem to be at different distances, for example, there is a clear gradient on the bottom row with the whitest tile seeming closest. The yellow tile seems closer than its W, NW, and N neighbors. The brown and dark green tiles on the top row seem farther back than their neighbors.

This isn't what I was talking about, though. I was talking about tile floors up to a century old with no maintenance, with inconsistent grouting and debris, and chips on the edges of the tiles, etc. These are what can rise to surprising apparent height.

Thanks - but not obvious to my 84-year old myopic brain. Looking again, I could indeed see some slight differences in apparent depth.