Before I start, I apologise for posting what I already know to be a fully-baked idea - but it's not a well-known idea and the instructions here will let anyone build a neat piece of kit that's fun to use.

By the way I built this back in 2001 and sat on it thinking I would patent it. An exhaustive patent search at the time showed no prior art. But I was too lazy and never did the paperwork, and now I've seen at least two of these home-brewed at exhibitions in the last year or two. That's my only justification for entering this as a half-baked idea, because like most of my hobby projects it never went past the prototype :-)

One of the earliest 3D displays was Edwin Land's system (US Patent No: 02084350 from 1935) with two TV tubes and two sheets of polarizing film, plus a semi-silvered mirror. The displays are placed 90 degrees to each other with the mirror at 45 degrees between them so they overlap when viewed through polarized glasses.

My design is to use two LCD flat panels, and *no* polarizing filter, because the panels are already polarized. And fortunately almost all flat panels are polarized at about 45 degrees (actually nearer 39 but it's close enough for this to work) so when placed at 90 degrees to each other with the semi-silvered mirror between them, by a wondrous piece of luck they are almost perfectly cross-polarized.

Back in 2001 I mailed the authors of several 3D graphics drivers and asked them to support this format (one of the displays needs to be mirror inverted - either horizontally or vertically, it doesn't matter - just rearrange the panels and the mirror to suit) and much to my surprise several of them did so, so you ought to find it relatively easy to make a home-brew system like this work.

The glasses you use are the standard passive ones as used at old-style (pre shutter-glass) IMAX cinemas. They're easily obtainable from Stereophotography vendors.

Any two-headed VGA card will work, like the very old Matrox I used in 2001, or cheap modern cards like the GEForce 5500 which can be had for $50.

I'ld love to see a new generation of arcade games use this technology. Many stand-up arcade boxes already use a 45 degree mirror to conserve space with large glass monitors. They'd be easy to tweak into using a semi-silvered mirror and two flat panel LCD displays.

Graham
-- gtoal, Jan 12 2006

Original posting by me in 2001 http://www.stereo3d.../643.html?994777197
with link to original 1935 Land patent. [gtoal, Jan 12 2006]

Planar display https://web.archive...nding/stereomirror/
Commercial version now on sale (not by me!) [gtoal, Sep 08 2006, last modified Dec 25 2019]

HD version https://web.archive...d.de/3dvideo-e.html
And another one [gtoal, Sep 08 2006, last modified Dec 25 2019]

Folding Stereoscopic computer display http://patft.uspto....282&RS=PN/5,598,282
Damn, beaten to the punch again :-( Patent filed 7 years before [gtoal, Nov 14 2006]

PS When I first thought of this I also thought of 3D contact lenses as a joke, not realising it was possible. According to the entry for "3D Contact Lenses" (qv) it is actually possible to design lenses which align themselves correctly in a vertical direction, so this should be very realisable. With big bright LCD TVs around nowadays which didn't exist when I built my prototype, a cheap home 3D IMAX ought to be very feasible. Unfortunately I rented one of the IMAX 3D DVDs last month to see how it could be displayed on such a system and it turned out that the DVDs are actually *2-D*!!! Grrr.
-- gtoal, Jan 12 2006


PPS (is it considered uncool here to follow up your own postings?) before anyone points out the ridiculous high cost of lab-quality semi-silvered mirrors - you don't need anything that good. Lab-quality mirrors can be very precise and give 50% reflection and 50% transmission; however glass sold for office windows etc is pretty damn close at a ratio of about 45 to 55. You can tweak the brightness on one of the panels to make them even. Google for a product called "MirroPane". Any local glazier ought to be able to order it for you.
-- gtoal, Jan 12 2006


i don't understand why is this called 3D. as i see it, all you get is a planar image projection, apparently in thin air. ingenious, but still, planar. in my opinion, real 3D imagery has to involve lasers.
-- sweet, May 19 2006


Long ago people used to view 2 photographs simultaneously in a handheld viewer. All you need is 2 displays as that is probably cheaper than alternating views to each eye through a filter and 1 display. Also makes refresh requirements slower.
-- Kirkmcloren, Aug 14 2006


I toyed around with this idea myself, except with flatscreen CRTs and polarizing film, but like you, couldn't find a driver that would send separate images to each screen.

One setup that I did get to work passably was FlightSim 2002 with WidevieW to display multiple views on multiple monitors. I just set up two views in the same direction, but with slightly varied eyepoints. It worked well as long as the onscreen motion wasn't too fast, but it pointed out a few graphical shortcuts that the coders took, such as drawing the airports as separate planar images on top of the 3-D render. While the terrain was visibly 3-D, the airports were always displayed identically on each screen, resulting in what looked like cutouts on a window, decidedly NOT 3-D.

If, as you say, drivers have been made to do this, I may just have to try it again next time I upgrade my computer. (no dual-head currently, can't justify buying a new card for my AGP-only motherboard just yet).

no [+] from me, since it is baked, and the concept has been baked for a long time (using a device with built-in polarizers instead of adding your own filter is not really a novel idea, although the grant-everything mentality of today's patent system may disagree)

But no [-] either, since I've been wanting a workable 3-D system for a while.
-- Freefall, Sep 08 2006



random, halfbakery