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Using Cellophane For 3D Displays On Your Laptop
prestidigital writes "From the abstract:
[the authors] present a novel, inexpensive, stereoscopic technique for generating 3D displays from cellophane and a laptop computer screen.
(Once again my physnews update sends me email that doesn't suck!)"
no duct tape?
My problem? I was perfectly gruntled, until some numbnuts came by and dissed me.
Cell o phone ???????
Okay, I just had to respond to this. I've been a long-time semi-dabbler in stereophotography, and naturally anything 3-D related on /. just jumps right out at me (sorry about the pun). This article, while organized in a scholarly-looking fashion, really doesn't present anything new whatsoever. In fact, if I'm reading it correctly, you can achieve exactly the same results with no cellophane at all!
They talk a lot about cellophane having natural polarizing characteristics (I'd never heard that, but okay). Then they talk about how laptops have polarizers built into them -- sure, I've known that ever since the glasses for Starchaser: Legend of Orin made my digital watch look funky. Where their article breaks down is in the actual application of polarizing technology on the laptop.
They suggest putting the right eye's image on the left half of the screen, and the left eye's image on the right, then using polarizing filters to ensure that each eye only sees what's appropriate for it. Great. No problem. Except that there is one problem -- when your left eye is looking at the right half of the screen, your right eye is looking there, too!!
In order for your brain to properly "fuse" the images together, your eyes will have to perform some tiresome calisthenics -- that is, your left eye is going to have to turn slightly right, to face the right half of the screen, while your right eyes turns slightly left. Basically, you're crossing your eyes.
If you're just going to cross your eyes anyway, drop all the cumbersome cellophane goggles and overlays and crap, and simply look at two images side by side.
Also, I'm not convinced that placing a polarizer over half the screen wouldn't just turn that half of the screen totally black (as shown in figure 2 of the paper).
The challenge for 3-D image display isn't blocking the "wrong" images from each eye, it's blocking the wrong images when they're displayed in the same space -- overlaid in a single frame. For that, you need colors (anaglyphic glasses), or polarizing filters (again, though, both images displayed in the same space), or lcd shutters (multiplexing the images in time, rather than in color or polarization). Or you can use a lenticular screen, that bends the images left or right and draws them in a series of interlaced vertical stripes.
But not what they're suggesting here. It all seems pretty useless to me.
[obCaveat: "Unless I'm missing the point entirely."]
Dude1: Hey, you been pr0ning again? Dude2: Erm, no way dude! Dude1: So why you got cellophane over your screen?! Dude2: 3D display man, 3d display Dude1: Aahhhhhh
I can't wait to try this with TuxRacer.
Boromir, son of Faramir, King of Gondor and Minas Tirith
Sheesh, evil *and* a jerk. -- Jade
I recommend wrapping the cellophane around your head. It takes very little time after application before things look 3D, an effect that lasts suprisingly long before everything goes black.
Platform independent bug tracking software
http://perljam.net/cache/individual.utoronto.ca/i
-ted
Porn companies have decided to ship Cellophane to their customers free of charge. ;)
smd4985
I believe displays that use this technique already exist, but couldn't you print a transparency with a special dot pattern, and place it over the laptop screen? The dots would be arranged so that the parallax from your eye spacing would block the pixels that the other eye can see. Laser printers have much more resolution than LCD screens, so you could adjust for the changing viewing angle from the center to the edges of the screen. You'd have to be able to control the distance from the mask to the screen pretty accurately, and there would be pretty much only one viewing position.
...
Using cellophane to convert a laptop computer screen into a three-dimensional display
Keigo lizuka
Department of Electrical & Computer Engineering
35 St. George Street
University of Toronto
Toronto, Ontario, Canada M5S 1A4
Abstract
We present a novel, inexpensive, stereoscopic technique for generating 3D displays from cellophane and a laptop computer screen. Stereoscopy requires independent manipulation of the left and right eye views.1 Our technique takes advantage of two facts; the first is that the light from the liquid crystal display of a laptop computer is polarized light 2, and therefore we can easily manipulate its transmission with a polarizer sheet. The second fact is that a cellophane half-waveplate can change the direction of polarization of light. The direction of polarization of one half of the laptop screen was rotated by the cellophane half-waveplate. Two images displayed with orthogonal polarization on two halves of the screen become separable by wearing a pair of glasses of orthogonal polarization.
A distinct advantage of our technique is its simplicity; a laptop screen can be converted into a 3D display with minimal knowledge of optics. An additional advantage of our technique is that we can eliminate the need for the observer to wear special glasses by making the computer wear the glasses instead. This is possible because a laptop computer normally has only one viewer at a time, and the relative orientation of the viewer's head and the laptop screen is sufficiently stationary. A further significant discovery is that we verified that cellophane (costing mere pennies) proved to be a better half-waveplate than a commercial half-waveplate (costing hundreds of dollars for the required size) for rotating the polarization of white light.
1. Properties of cellophane
Let us begin by examining the properties of cellophane. Cellophane is fabricated by protruding an alkaline viscose solution through a narrow die into an acid bath. Because of the unidirectional strain during the protruding process, cellophane is an anisotropic material and it behaves like a calcite crystal. The refractive index ny of cellophane measured by a light wave component polarized in the direction of the longer dimension of the rolled cellophane (in the y direction) is larger than nx, measured by a light wave component polarized in the direction of the shorter dimension (in the x direction).
As a result, the component polarized in the x direction propagates through the medium faster than the component polarized in the y direction. After transmission through such a medium, a phase difference arises between these two light wave components. The difference ny-nx in the refractive index and the thickness of the cellophane determine the amount of the phase difference between the components polarized in the x and y directions. A medium that creates a 180o phase delay is a half-waveplate. The phase difference incurred in plain ordinary colorless cellophane (our sample had a thickness of 25 microns was measured to be 170.2o , which is about 95% of the phase delay of an ideal half-waveplate. These measured results are within acceptable limits for a number of practical applications that do not require a precise 180o phase delay. Having demonstrated the feasibility of using cellophane as a half-waveplate, we now examine what a half-waveplate does and how it can be used to create a 3D display.
One of the most important functions of a half-waveplate is its ability to rotate the direction of polarization of the transmitted light. We found that cellophane's performance in rotating the direction of polarization of white light was superior to that of a commercially available half-waveplate designed for a specific wavelength. An added bonus is that cellophane is very inexpensive. Before describing the role of a half-waveplate in generating 3D images, we need to introduce some basic stereoscopic principles.
2. Stereoscopic principles
Figure 1 explains the basic principle of
Using cellophane to convert a laptop computer screen into a three-dimensional display Keigo lizuka
Department of Electrical & Computer Engineering
35 St. George Street
University of Toronto
Toronto, Ontario, Canada M5S 1A4
Abstract
We present a novel, inexpensive, stereoscopic technique for generating 3D displays from cellophane and a laptop computer screen. Stereoscopy requires independent manipulation of the left and right eye views.1 Our technique takes advantage of two facts; the first is that the light from the liquid crystal display of a laptop computer is polarized light 2, and therefore we can easily manipulate its transmission with a polarizer sheet. The second fact is that a cellophane half-waveplate can change the direction of polarization of light. The direction of polarization of one half of the laptop screen was rotated by the cellophane half-waveplate. Two images displayed with orthogonal polarization on two halves of the screen become separable by wearing a pair of glasses of orthogonal polarization.
A distinct advantage of our technique is its simplicity; a laptop screen can be converted into a 3D display with minimal knowledge of optics. An additional advantage of our technique is that we can eliminate the need for the observer to wear special glasses by making the computer wear the glasses instead. This is possible because a laptop computer normally has only one viewer at a time, and the relative orientation of the viewer's head and the laptop screen is sufficiently stationary. A further significant discovery is that we verified that cellophane (costing mere pennies) proved to be a better half-waveplate than a commercial half-waveplate (costing hundreds of dollars for the required size) for rotating the polarization of white light.
1. Properties of cellophane
Let us begin by examining the properties of cellophane. Cellophane is fabricated by protruding an alkaline viscose solution through a narrow die into an acid bath. Because of the unidirectional strain during the protruding process, cellophane is an anisotropic material and it behaves like a calcite crystal. The refractive index ny of cellophane measured by a light wave component polarized in the direction of the longer dimension of the rolled cellophane (in the y direction) is larger than nx, measured by a light wave component polarized in the direction of the shorter dimension (in the x direction).
As a result, the component polarized in the x direction propagates through the medium faster than the component polarized in the y direction. After transmission through such a medium, a phase difference arises between these two light wave components. The difference ny-nx in the refractive index and the thickness of the cellophane determine the amount of the phase difference between the components polarized in the x and y directions. A medium that creates a 180o phase delay is a half-waveplate. The phase difference incurred in plain ordinary colorless cellophane (our sample had a thickness of 25 microns was measured to be 170.2o , which is about 95% of the phase delay of an ideal half-waveplate. These measured results are within acceptable limits for a number of practical applications that do not require a precise 180o phase delay. Having demonstrated the feasibility of using cellophane as a half-waveplate, we now examine what a half-waveplate does and how it can be used to create a 3D display.
One of the most important functions of a half-waveplate is its ability to rotate the direction of polarization of the transmitted light. We found that cellophane's performance in rotating the direction of polarization of white light was superior to that of a commercially available half-waveplate designed for a specific wavelength. An added bonus is that cellophane is very inexpensive. Before describing the role of a half-waveplate in generating 3D images, we need to introduce some basic stereoscopic principles.
No, because your right eye is wearing a polarizer that blacks out the right half of the screen and lets it see only the left half. See figure 3.
cellophane has a poor separation quality, i.e the difference between 90 degrees (blocked) and 0 degrees (pass) polarized light is little.
Real lab-quality polarizer crystals are way to expensive and generally too small for this application.
however, sheet polarizing material can be bought in photo equipment stores and cut to size with normal scissors. It's more expensive than cellophane but less expensive than lab polarizers and has a quality that is waaaaay better than cellophane. I paid about 15 bucks for 25*25 cm. about 8 years ago in Germany. Hama sold them at the time
This animated GIF technique showed up on Metafilter a couple of weeks ago, and for me it was one of those "Why the hell didn't anyone try this sooner" epiphanies for me. Yes, the constant jitter while flipping between frames gets old, but not nearly as old as straining your eyes with the 'cross-eye' viewing method.
... so their burgers don't look so flat.
Buy Steampunk Clothing Online!
I'd hate to have to peel off the melted cellophane from the LCD.
Alex.
So I didn't RTFA.
I'm assuming its similar to this .
I just hope the solution was more inventive than doing the old theatrical movie stunt about using relative shifting of color information and celluloid glasses - which gives you depth information at the expense of color information. Spy Kids 3D just did this using a blue or green image for the left eye and a red image for the right.. That one's been around since the 40's. In both movie and book. Cute trick but it gives me headaches to see it for any length of time.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
I guess that this is more proof of the old saying that technology is driven by either
a) Man's desire to impress women
b) Man's desire to find a subsitute for women when he is rejected
This idea has been around for years. I first saw in the "Garage VR Handbook", which was published in the early 90's.
Sigpilot : I'm in the pipe, 5 by 5.
Here's a short but decent article on the same research.
Yes, those animated GIFs achieve a 3D effect. They do so via motion, however, not via stereo--a completely different mechanism. You can actually be blind to depth from motion and still perceive stereo and vice versa. The fact that it works by alternating between stereo pairs has to do with the way motion perception works.
Using motion to indicate depth has a long history in computer graphics. The obvious problem is that it requires the viewpoint or the object to move significantly, not always desirable.
Images that use motion to indicate depth don't have to look as horribly jittery as those animated GIFs: the effect works just as well with nice, smooth motion sequences. So, get out your camcorder and make some nice animated images.
So I figured I'd shake my head, synchronized, in the opposite direction of the image shake, separating my eyes with my hand. I studied, ahem, one of the pictures for quite a while to get it right.
:)
It works - real stereo viewing.
And gives me quite a headache.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Couldn't I just take a regular old CRT monotir, put celophane over the right half to polarize it, then put another pice of celophane over the left half, but rotated 90 degrees, and still end up with two halves of a monitor polarized 90 degrees from each other?
paintball