Stereogram Tetris
lutanho.net
lutanho.net
When I was a kid I was obsessed with inventing a 3D TV. I went to the library and tried to understand how holograms worked and everything. I was so intrigued by stereopsis that I would constantly try to get any two similar objects in my field of view to "combine" by crossing my eyes until they locked. I'd hold my index fingers in front of my face, and then either cross my eyes or stare past them to bring them together, and see how far I could move them apart before I lost the lock.
I obtained the power of exceptional vergence. I was actually surprised to find that only two or three people I've met can make non-auto-stereograms (two photos side by side) work at all. And to this day, autostereograms resolve automatically for me.
My only weaknesses are cheap faux wood flooring and other short period tilings.
And Tetris. Man I suck at Tetris.
You know how when you cross your eyes you get like two different perspectives of whatever you're looking at? Well if you focus in the right way, there's a "middle" perspective between those two. That is where I can see these stereograms or whatnot.
Try it on this picture of a dinosaur[1], notice the 7 white bird-like shapes repeated across the page. Cross 2 of those over and you should see the image of the dinosaur appear.
What you're describing is the cross-eyed way. The parallel way has the disadvantage that the separation between the two images can't be too big (no more than about 5 cm at arms length is my guess), while cross-eyed images can have very large separation (e.g. two side-by-side images[2]).
In return, once you learn how to put your eyes into parallel mode, it's incredibly easy and quick to do so compared to cross-eyed viewing, and much much less taxing on your eyes (since they are pointing in only slightly unnatural angles), and with more easily discernable details.
(also, if you try to view an image with the opposite viewing method it was designed for, it'll come out with the depth inversed, e.g. the raptor image linked by another poster[3] should stand out, rather than look "punched-in")
[1]: http://www.vision3d.com/3views.html
[2]: http://farm3.staticflickr.com/2073/1620326328_6dc93774bc_z.j...
The way I assume it works is that our brains naturally filter out patterns so we can see the interesting stuff. In a stereogram, the underlying image is XOR'ed with a random pattern that is repeated, and therefore filtered out by our brain. Interestingly, the repeated pattern is not constant, so if you XOR the image against the first instance of the pattern it will look increasingly noisy as you get further into the picture.
So I'll describe what you should expect to see. The image consist of 3 equal sized columns. Left and right columns are not part of the tetris field and have the same depth with the page itself (Z=0). Middle column is the tetris field with 5 playable columns which is the deepest layer on the page (Z=-2). And the tetris pieces are on an intermediate layer between those two layers (Z=-1). You now should be able to imagine what the game will be like. Hope that helps.
It takes about a second to figure out what each new piece is, though.
And I'm pretty sure my eyes would ache horribly if I played it for more than about two minutes.
But, fascinating just to see that it can be done.
A while back, I watched Captain America in side by side mode on my computer. Only problem was that in SBS they put the left eye on the left and the right on the right. To view that as a stereogram would require "wall-eyed" vergence, which is basically impossible to do beyond a certain angular distance - I'd have had to watch it all tiny. So as an experiment in perceptual adaptation, I watched the whole movie cross-eyed, so that I perceived the depth as inverted.
It wasn't really enough time for full perceptual adaptation, although by the end of it, I basically found that my brain had stopped paying attention to dept whatsoever unless I consciously thought about it.
Anyway the point is that at the end, I let my eyes slide back into their normal state, and they burned for a while after like they were dry, but they didn't ache at all.
That said, I have spent a ludicrous amount of time in my life setting my vergence to values outside of the manufacturer's recommended range. So my results may not be typical.
BTW, the book which introduced RDS: "Foundations of Cyclopean Perception" by Bela Julesz is considered one of the most influential books in cognitive science. With just a computer, using no invasive microelectrodes and animal sacrifices, he proved a fantastic result...stereopsis (fusion of the individual images from each eye) occurs before object recognition!
1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 2
3 3 3 3 3 3 3 3 3
4 4 4 4 4 4 4 4
5 5 5 5 5 5 5
6 6 6 6 6 6 6
7 7 7 7 7 7Can't lock on, and gives me eye-ache within minutes.
So if you're having trouble, you're not the only one. It might be wonderful, but despite finding auto-stereograms easy, I can't see this at all.
Ended up alright though; score of 2080, and that's only because I lost vision after sneezing. This is a fun little concept.