TITLE: Orthonormal
NAME: Tekno Frannansa
COUNTRY: UK
EMAIL: tek@evilsuperbrain.com
WEBPAGE: http://www.evilsuperbrain.com
TOPIC: Architecture
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
RENDERER USED:
POV-Ray for Windows v3.5
TOOLS USED:
POV-Ray editor
RENDER TIME:
2 minutes 16 seconds
HARDWARE USED:
Athlon 2200 512MB RAM
IMAGE DESCRIPTION:
I've been fascinated by this kind of illusion since I was a kid, looking at Escher's drawings. I remember thinking about it and working out that if you had shadows or reflections or similar real-world details then the illusion would fall apart and you'd see how it was done, so I decided to make a scene to prove myself wrong! Everything's slightly reflective and there's lots of shadows, and yet the image still has that wierd disorienting feel that an escher picture can give.
Incidentally, the title "Orthonormal" is a slight abuse of a mathematical term for a type of matrix. I felt it was appropriate because of the widespread use of unit cubes and it's similarity to the word "abnormal" :)
Viewing reccomendation: to avoid headaches I suggest covering the right side of the image and just looking at the left, and then revealing the left gradually. Also it's entertaining to put it in a paint program and rotate it 180 degrees, only the pattern on the marble changes, nothing else moves.
DESCRIPTION OF HOW THIS IMAGE WAS CREATED:
Okay, this is the spoiler. The trick is I create half a scene, with all lighting as part of a light group, then I copy it and rotate the copy through 180 degrees around the camera's axis.
Still not clear? Okay, well there's a few things to understand here. Ignoring shadows and reflections, a cube viewed from an angle where you can see 3 faces looks exactly identical to an inverted cube (i.e. the 3 other faces) lit from the opposite side, if there's no perspective. I think I just explained that really badly! This isn't just true of cubes, lots of other shapes work just as well, but it's easier to find situations involving "inverted" cubes.
The really simple explanation (skip this if you get it already): Think of buttons on windows your computer pops up, notice how the top and left sides are coloured light, and the bottom and right sides are dark? Well that's just a convention suggesting there's some imaginary light off the top left of the screen. The illusion works by having some things lit from that side, and some things lit the other side so they look like pushed in buttons even though they're not. Mix them together just right and you can't tell if you're looking at a point on a cube that points towards you or away from you.
Now, within this system of cubes I construct a few objects that cannot be made to look like their inverse. This gives you a few points to focus on that clearly contradict each other, so your brain tries to find the break between these two worlds (the up world and the down world) and when it can't you get that strange sensation that increases sales of aspirin.
On top of that I added my website logo as a little sculpture, which I rotated so that the "up" and "down" versions look the same as their closest counterpart, apart from the lighting. And then I added shadows and reflections, with a lot of tweaking to avoid the many errors that are inevitable in this kind of scene.
I've provided the full source code, just one pov file, so you can turn on my debug code and see where the edge is.