Colograms - A simple way to create stereoscopic images

Dragon
Bill Beaty says "The author is making his own version of those 3D advertising signs popular in the late 1980s. (I saw many of these mounted on the walls of corridors at large airports.) They're "lenticular" 3D which uses pinhole optics rather than cylinder lenses." Link.




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Posted by: Oracle1729 on September 20, 2006 at 2:55 PM

Why create a new name (Cologram) when there already is a name. This is a 3D Lentricular image.


Posted by: Shadyman on September 20, 2006 at 3:12 PM

I guess 'Lentriculogram' doesn't have the same ring to it.


Posted by: supertim on September 20, 2006 at 4:02 PM

I think it's time to try this with an LCD monitor to view 3D video. Does anyone know where to find some 3D video content to try?


Posted by: wbeaty on September 20, 2006 at 4:25 PM

It probably already has some other name other than "colorgram." IIR, the company who was making them in 1988 was founded by students from University of ?Indiana?

"Lenticular" uses an array of lenses, but this method does not. When building a pinhole camera, would you call the pinhole by the name "lens?"

It's not a lenticular display ...so it must be "slot-ticular?"

:)


Posted by: monopole on September 20, 2006 at 5:12 PM

The proper term is "parallax barrier display" and it is an old trick (the sharp LCD 3d displays use a variant).

This is very neat implementation in that it uses the same printer to generate the mask and the image allowing for reasonably good registration. Registration is always the tricky part with lenticular and parallax barrier techniques.

be sure to have a bright light table as well in that this method blocks a lot of the light (at a minimum 60%)

With LCDs the situation is tricky in that each pixel is split into three sub-pixels (red, green and blue) which can cause color shifting. But use of a thinner tilted mask coupled with a interspersing color channels allows for up to nine seperate images to be implemented.


Posted by: monopole on September 20, 2006 at 5:26 PM

One other thing, the free visualization toolkit (VTK) has native support for this sort of display just set the render window to StereoRenderOn() and SetStereoTypeToDresden() (based on the old ELSA/University of Dresden displays)and any VTK application will generate an appropriate image (use the vtkWindowToImageFilter to capture the resulting image)

You can get VTK from:
http://www.vtk.org/

The excellent EnThought Python distribution also incorporates VTK:
http://code.enthought.com/enthon/


Posted by: aolshove on September 21, 2006 at 7:41 AM

I'm confused. This doesn't look 3D at all to me. So, how is it supposed to be viewed?


Posted by: aolshove on September 21, 2006 at 7:42 AM

I'm confused. This doesn't look 3D at all to me. So, how is it supposed to be viewed?


Posted by: monopole on September 21, 2006 at 7:50 AM

aolshove
The image consists of three perspectives split into interspersed stripes (like feeding the three perspectives through a shredder and pasting them together cycling through one stripe from each photo). To view the image you use a striped mask offset from the image by ~2mm.
For more info RTFA


Posted by: monopole on September 21, 2006 at 8:06 AM

A good discussion of the Parallax barrier technique (and a variety of other displays) is in this paper:
http://citeseer.ist.psu.edu/cache/papers/cs/30003/http:zSzzSzwww.dur.ac.ukzSzcomputer.sciencezSztechnical-reportszSz2002zSztech-report_05_02.pdf/d-display-systems.pdf

The discussion of parallax barrier displays starts on page 22


Posted by: wbeaty on September 21, 2006 at 10:09 AM

[i]I'm confused. This doesn't look 3D at all to me. So, how is it supposed to be viewed?[/i]

That image must be placed behind a black slot-mask. Or it could be placed behind an array of cylinder lenses, as with those three-D religious postcards.

The image on Make Blog contains all the 3D information in the form of multiple viewpoints compressed into narrow vertical swaths of pixels


Posted by: JohnKit on September 21, 2006 at 1:19 PM

I've seen parallax barrier/lenticular kits that you can buy in computer stores in Thailand. It had some software (simple image manipulation, 3D title maker, and the lenticular program) along with a picture frame that had a screen of the ridged lenticular material. The whole thing looked very cool. I think it was being sold by a printer maker, but I can't remember what one. I do a bit of stereo photography here and there and was quite intrigued with it, but sadly not enough to buy the kit. The free software in the DIY article should be fun to play with though.


Posted by: wbeaty on September 21, 2006 at 7:12 PM

The lenticular kit is EZ3D,

http://digigearinc.com/


Posted by: wbeaty on September 21, 2006 at 7:17 PM

Looks like the lenticular array panel itself is on amazon for $25:

http://www.amazon.com/exec/obidos/ASIN/B000FQ2M1E


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