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Graphics Software

Poor Man's Stereoscopic Projection 132

Posted by timothy from the you-supply-the-cart dept.
Jed Link writes: "This summer I helped built a Geowall stereoscopic projection (3D) system for the Southern California Earthquake Center. Although there are no new concepts involved with this system, what is new is that the system cost a little over $10K and is comprised of materials that you can buy at any computer-hardware store. A complete description of the system, as well as a diary of its assembly is available here. Traditional stereoscopic projection systems like The Cave which is used primarily for new product modeling and on a few university campuses cost anywhere from $150K to $1.5M. They are built into a fixed location, often requiring significant architectural modifications, so transportability isn't even an option. The Geowall, on the other hand, can be fixed to a cart (like we've done) and rolled from room to room. The price-tag makes the system feasible for undergraduate post-secondary education classrooms and even high schools. The system is based on a very simple concept, and while its use is currently primarily educational, I think it's only a matter of time before we see something like this in the gaming or entertainment industries."
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Poor Man's Stereoscopic Projection More

Poor Man's Stereoscopic Projection

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  • $10K? (Score:3, Funny)

    by Anonymous Coward on Thursday September 05, 2002 @06:58AM (#4199294)
    Not exactly poor man then. More like upper middle class.

    Oh well, back to looking at my 14" screen.
    • Well, from an educational institution's point of view, though...


      What impresses me about this is that it exploits above all the brain's capacity to justify visual data... Rather than attempting the perfect visual justification through hardware or software. This "good enough for gub'mint work" approach is perfect for the job at hand - since most of us are blithely carrying a fantastic image-justifying supercomputer around on our shoulders.


      Hmm, now to just extend it to MOVING pictures...

  • Bear with me here. I'm a little slow. Are you saying you could use this thing to turn a small room into a virtual environment (like the holodeck) for gaming? A room like my living room? For 10K? Cool.
    • No, it's saying you could project your PC's onto your wall a display similar to what you can do now with a standard computer projector, but by wearing special glasses, you'd be able to see depth in the image.

      It uses the well understood method of polarising two images, overlaying them, and wearing glasses with polarised lenses, so you see a different image with each eye. But it does it very cheaply by using a standard dual-head video card to drive two standard computer projectors.

      Actually I imagine you could do this for under $10K easily. Cheap computer projectors are what, $2000 each? $100 for a cheap dual-head card - more for an expesnive one if you plan to play games. The filters and glasses can't be that expensive. Of course, you'd need software that produces the appropriate pair of images, but TuxRacer and Quake are both open source, so I'm sure it can't be that hard.
  • I think that perhaps traveling systems like these could do wonders to teach and inspire children (K-12) about mathematics.

    Maybe even get them fired up about graphics and visualization research.

    At least it can be a cheap way to setup and show 3d movies.

    One small step for man, one huge leap for Muppets in 3D.
    • I think what you say is the absolute best use of this technology. Has anyone ever seen the PBS college course by that professor from MIT who is teaching a beginning physics class? That series uses pretty impressive computer graphics to demonstrate ideas. I see this system as taking that excellent idea one step further by adding 3D. If students can actually SEE magnetic fields doing their thing in 3D space they will quickly understand some concept being taught. Actually SHOW them what the inside of a jet engine looks like while it is operating in 3D and they will pick up the ideas much better abd more quickly. And that doesn't even take into account geologic commercial uses for this technology. The fact that this is portable and relatively cheap means that A/V departments in schools and small businesses can have some of these things, and not just big companies/research institutions.

  • Sure... (Score:3, Funny)

    by Quixote ( 154172 ) on Thursday September 05, 2002 @07:09AM (#4199323) Homepage Journal
    It costs 10K now, but once the p0rn industry gets into the market, we'll all, errr.. I mean, you'll all be able to buy it for under $1K with economies of scale.
    • You may not be aware of this, but there have been 3D porn movies for some time. The Egyptian Theater in Seattle sometimes shows them for their midnight movies on the weekends. Pretty goddamn amusing stuff.
      • You may not be aware of this, but there have been 3D porn movies for some time.

        Anyone know if any (many?) of the major computer video formats (AVI, QuickTime, MPG, etc.) have specific support for 3-D?
        • Well, I know Quicktime has a panorama view, that lets you see in 3D, but I've never seen an animated example of this, although I'm sure it must be possible, if a little data-intensive.
      • Yah, I'm sure there's nothing quite like having Long Dong's penis thrust out of the screen and into your face... [shudder]
    • You are correct sir. I had a college professor who taught telecomm back in 1993. His doctoral thesis was based on the idea that the porno industry has been at the root of making any new entertainment technology cheaper. VCRs were his prime example at the time. Now, I am sure he talks about the internet boom. After all, what other use is there of r a fast connection? ;P Not the *I* download a lot of porn or anything.
  • ...then open up your Q3A console and type "/r_stereo 1" followed by "/vid_restart"
    (change the value of cg_stereoSeparation to suit your taste) ;)
  • Gotta buy one. I can't be the last geek in Michigan without one.

    I use real caves on a daily basis. Looks like I'll try building this one at home to see if it can compare to the ones at work.

    The biggest issue I see is having a room long enough to put the projector(s) behind the screen far enough to make it large enough to have fun with.

  • why would secondary school education need something like this?

    some please point this out to me
    • Because doping our kids up with ritalin just made them drowsy. That and it would have made Calc 2 in highschool SO much easier to visualize.
    • Imagine if you will a Science presentation on the Solar System. Watching badly edited documentaries from the 1950's, or slides that are so old and grainy they look like ink-blots.

      Now imagine if they could pop up an image of the Sun that's 10 Feet x 10 Feet in full 3-D. Viewing the properties of Sun-spots up close or watching a prominence burst forth. Then going to a 2/3 view and showing the different layers of the sun and how they all work. Then zoom into the core and show a representation of the fusion process. Or pull out and watch the death of the Sun and how it swallows up the Earth. Then moving on to the other planets. Driving around the Martian surface, or doing the Voyager 1-2 tour. All of it done in stunning 3-D.

      Or the Chemistry class where instead of the teacher drawing the various bonds on a chalk board he/she slips on a modified Power-Glove, /* You remember those, 80's 8-bit Nintendo VR controller. */ and actually grabs the different molecules and puts them together and then Rotates them so you can see how they're all combined.

      What about the Biology class where instead of talking about DNA or looking at it in a book the teacher could put up a floating 3-D replica of it then manipulate it. They could show a heart beating and isolate the various chambers to show what they do. Then zoom out to show the entire circulatory system. Or phase it out and concentrate on the bone structure or nervous system. It would definitely go a ways into appeasing those who are ambivalent towards the dissection experiments.

      You could even use it in Art classes to show different sculptures, landscapes, and monuments from around the world.

      Or a History class that depicts various moments in history. Imagine watching D-Day in 3-D. Placing you in the action so that you could begin to have an idea of what it might have been like to be there.

      Hell, you could even use it in Sex-Ed. Get rid of those incredibly bad 70's movies with dialogue worse than a Blacksploitation flick. You could actually show an egg leaving the ovaries, roll down the fallopian tubes and into the womb. Or show sperm production from scrotum to ejaculation. All the while rotating, and zooming in and out for effect.

      This would be an invaluable tool for Secondary Schools. Most kids don't pay attention as it is because the classes are "boring", lots of facts and figures but no real way of putting it together. You either get it, or you don't. But this way you could actually "show" the kids what you're trying to teach them.

      Make it fun, make it exciting, or at the very least interesting, and I think you'll start seeing kids understand and care a little more about learning than they did when I was in school.

      For $10,000.00 I can't imagine why any school shouldn't have this type of set up.

  • Missing the point (Score:5, Informative)

    by Anonymous Coward on Thursday September 05, 2002 @07:23AM (#4199345)
    The author is completely off the mark in comparing his "geowall" ($12k, mobile, stock parts) to a cave system ($120k, fixed, custom parts). The projectors are easy for a cave, too. They cost a few thousand dollars, and use the same NVIDIA trick as he does. What is expensive and difficult is the motion/orientation-tracking system. The last cave I was in used a magnetic field to precisely detect the position and orientation of the viewer, thus moving the image ot make it seem like you were crawling around inside the scene. This has to be pretty precise, IIR, or else it feels wrong. And getting a good rectilinear magnetic field the size of a room takes lots of metal -- hundreds of pounds of shielding, permanent magnets, electromagnets, etc -- positioned very carefully all over the room. Not to mention the sensors. This is the part that costs $100k.

    • Re:Missing the point (Score:3, Informative)

      by cyranose ( 522976 )
      I don't know about the CAVE you were in. But on the ones I've built and/or been in, the trackers weren't necessarily the driving cost. Here are some of the big costs in the past:

      1. 4-6 high-end stereo-capable video channels (typically big iron SGI or smaller but heavily synchronized computers) doing 120hz rendering of large datasets

      2. Infrastructure -- custom-built cube, often raised off the floor for bottom to work, requiring risers, stairs, and quality construction for insurance purposes

      3. 4-6 x 8'-10' fixed panel rear-projection screens (that preserve polizaration, not an easy trick)

      We were able to reduce #2 with wood construction, omitting the raised floor. We also found that for entertainment apps, head tracking wasn't the most important thing, so for #1, somewhat cheaper computers and no tracking is an option. For #3, cheaper acryllic screens are fine if you don't need passive stereo (which you don't if your virtual objects are greater than say 12 feet from the viewer or you use active stereo).

      Bottom line: we built a cheap-ass CAVE in 1993 for under $30k not counting the computers (which were over $300k back then). With new PCs, new projectors, and some clever predictive synchronization over simple ethernet, we could be talking $6k per wall without stereo, $10k with. Add decent tracking, and you add maybe another $10k overall. Add labor costs, markup, and an insurable level of steel infrastructure and that gets you near the $120k for current CAVE systems. But cheaper is always an option. For example, in my home, I use non-stero and an 8' screen made of stretching a 300 thread king-sized bed-sheet over a custom wood frame (it's as good or better than many screens I've used).
      • (that preserve polizaration, not an easy trick)

        Your CAVE uses polarization? The one that I've used uses LCD shutter glasses.

        Polarization would certainly cut down on the expense of the glasses (despite the cheap ones you get with some consumer video cards, GOOD LCD glasses are expensive) with the disadvantage, as you note, of increasing the screen cost.

        By "active" and "passive" stereo are you drawing a distinction between, say, LCD glasses and polarized glasses?

        • Yeah. The advantage of passive (polarized) is cheaper/light/more-comfortable glasses, less (or no) flicker. Circular polarization is probably best, since standard linear polarization breaks down when you tilt your head. But the screens are almost non-existent for read projection passive. (This job calls for transparent aluminum :)
          Even good active (LCD shutter) systems also have flicker and extinction problems (cross-talk between the eyes because the LCD can never go 100% dark or change at 100% of the speed you need) which kind of ruins the stereo effect for me personally. These projectors are also more expensive--to get 60HZ for each eye, you need 120HZ total, right? Two standard 60HZ projectors might actually be cheaper and brighter in the long run. Both methods have the pitfall that they're losing half or more of the projector's power.

    • Re:Missing the point (Score:1, Informative)

      by Anonymous Coward
      No, wrong. I run a CAVE. The tracking system is a 1' square box, that is expensive ($10-20k), but not
      the most expensive part. Up until a few years ago, the only thing that could really run a CAVE was an SGI Onyx2 or equivalent. Those are expensive. Even today, the inexpensive graphics cards we use for gaming don't do what a 6 year old Onyx does, things like syncing the display signal, stereo frame buffers, etc.

      Systems like the Geowall are the next step, but we still have to cut corners to get them to work, thats why we use two projectors to create a stereoscopic image. Ever try to do stereo with a DLP projector?

      And for us, the hardest part of the CAVE is still the same, it's finding a room to put it in.

    • So you're telling me that technology that can be found in an arcade (Police 911, the boxing game, etc.) that track my movements and map them to effects and movement on the screen costs 100K? Without shielding, magnets, sensors that are on me? Granted, it's not room size, but it's also not a controlled enviroment.

      Jester.
    • This is wrong in so many ways, I don't know where to start. The projectors for a CAVE are completely different from the ones used for the Geowall. They are usually big CRT projectors that cost around $20k a piece. If you are one of the lucky few that have 3-chip DLP projectors like the Mirage, they cost you at least $50k a piece. These are for field sequential stereo and aren't using any kind of "NVIDIA trick".

      If you are using a magnetic tracker you don't have "hundreds of pounds of shielding, permanent magnets, electromagnets, etc". There is a transmitter that's about 1' cubed in size and several 1" cubed sensors. Metal tends to interfere with the tracking due to induced currents, so you want for there to be a little metal around your tracked area as possible. The 6 sided CUBE at the Beckman Insitute at UIUC is made completely out of wood for this very reason. There's usually only one transmitter and it doesn't have to be positioned very carefully. All the XYZHPR readings from the sensors are relative to the transmitter, so you just have to calibrate it once and you're good to go. Also, a magnetic tracker doesn't cost anywhere near $100k. More like $20k. Check out Ascension [ascension-tech.com] for their Flock of Birds which is the most commonly used magnetic tracker for immersive displays. Now, if you're using something like the InterSense tracker with their nifty new wireless sensors, it can get pretty pricy, though probably still under $100k.
  • Its a cool idea but I thought that the since our eyes are in a horizontal direction the projectors should also be in a horizontal direction. Whereas this system is putting the projectors in vertical direction. I don't know how it will look with the vertical projector placing. The main price of this setting is anyway getting the two projectors.
    • The two images are projected over each other, so it doesn't matter where the are, as long as they are close enough to each other (and there is enough room for ventilation and so - their first (plastic) polarizing filters melted from the heat).
    • The reason that the projectors are mounted vertically vs. horizontally is simple, the projectors used would need a horizontal keystone ajustment to mount them next to eachother. These projectors were orginally designed to be used alone. It is reasonable for the manufacturer to assume that adding a horizontal keystone ajustment wouldn't be cost effective in this low-end of a projecor because they are usually placed center perpendicualar to the projection surface anyways.
  • You could easily knock off another 1000 USD by building the computer yourself. That's one of the more expensive (read server) dualie boards out there.

    Plus it would be nice to be able to script the creation of the images to make movies. Can The GIMP be made to do this? So if you were able to avoid using Windows XP and Photoshop, my guess is that you could really come close to having a sub-10k setup today.

  • A thesis work related to the subject (Score:5, Interesting)

    by jukal ( 523582 ) on Thursday September 05, 2002 @07:29AM (#4199361) Journal
    I read this Licentiate Thesis [eve.hut.fi] work sometime ago, and if you are interested in getting to know virtual reality/environment techniques and CAVE construction it is excellent. It's PDF and over 700K, 146 pages.
  • Well, the ones who really need it (car designers, whatever) probably care about the 'minor imperfections' and are willing to spend the additional 140K. As for the others... well... i think i'd rather spend 10k on regular CRT monitors + stereoscopic glasses (the ones making your left/right eye see even/odd frames). I am too lazy to look up the price tags on these, but my guess is i can get a whole monitor + glasses set well under 500$. So, 20 sets that can also be used as regular monitors instead of one projection set seems a good deal to me.
  • And here I was thinking there's an easy and cheap way to make stereoscopic videos!

    After reading it I think I'm gonna stick to my Asus 7700 with the polarizing lense that came with it.

  • SGI (Score:3)

    by lovebyte ( 81275 ) <lovebyte2000&gmail,com> on Thursday September 05, 2002 @07:35AM (#4199375) Homepage
    These things are quite commonly build out of one expensive projector and an SGI box. There are many of these and they are mostly used for viewing 3D models (of geological surveys, cars, proteins, ...) for a group of people. If you are alone, then you can easily use active stereo on a big CRT screen.
    I think it is interesting that these people have done a cheap version of a one-wall cave, but caves are most impressive when you have more than one wall! I've personnaly used caves of 3 (floor and corner) and four walls (floor and 3 vertical walls, i.e. a room without ceiling and one wall), and I know of people who have played Doom in them. They told me that it was physically tiring because you had to move, duck, ... Maybe that would be a good training for geeks wanting to work for the FBI!
  • Use the homebrewed projectors "Slashdot|Homebrewed LCD Projectors" [slashdot.org] instead of off-the-shelf and the price should become pretty reasonable ($1-$2K tops I would think).
    • Since such projectors are likely to have a lot of compromises.

      On the other hand, it's theoretically possible to make projectors more suited to a task.

      Finally - Search hard enough and you can get used LCD projectors for $1000. Resolution will be a bit low tho. I'm assuming 90%+ of that $12k was for the projectors. (Maybe only 80% - They did use a Quadro4...)
      • LCD Projectors use polarized light internally to build the display field. So unless you plan on turning one of the projectors 90 degrees to the other, you'll have problems trying to use LCD projectors.

        Of course if you do use LCD projectors then you'll no longer need the external polarizers. You'd only have a square overlapping projection area to work with, and the display software would have to rotate one of the two images on the fly, but other than that it might be doable.

        • The problem has already been worked around, although in a reverse manner.

          The autofocus and metering systems in modern cameras do NOT take kindly to polarized light.

          So how do you use a polarizing filter? A circular polarizer. Basically, it consists of a linear polarizing layer followed by a quarter-wave retardation plate of some material that will take the polarized light passing through the filter and convert it to circular polarization. (Not sure of the exact mechanics of how it works, but in short they somehow convert a linear polarization to circular.)

          So one would simply need to do this in reverse with an LCD projector - In fact, one might even be able to use circ polarizers designed for cameras.

          It will probably have higher loss (reduced brightness) than a system with a DLP projector, but it should probably still work well.

          I'll try it tonight with my 72mm circ and my projector.

    • Won't work. The article specifically mentions the use of PLD projectors, not LCD, because LCD displays already uses polarized light to turn the pixels on and off. Put an extra polarization filter in front of it and you may not see a thing. It is not possible to generate two beams with a 90' polarization difference this way. Unless you rotate one of the LCD displays 90', but then you must rotate the image too, plus they are not square, etc...

      Sorry, but this ain't going to be this cheap :-)

  • I've seen a fair few 3D systems lying around - already, universities have 3D projection systems, and these are often used in CAD visualisations.

    To be able to view 3D images without 3D glasses is crucial to the success of such a system, especially if it is to be marketed to consumers. There are all kinds of systems involving glasses, from the basic red/green system to (I don't know if this has been tried; if not, I was there first!) using two projectors with polarising filters, and glasses with polarised lenses, which preserves colour.

    I remember seeing on Tomorrow's World several years ago a demonstration of a 3D TV, which required glasses to view. Bizarrely, the footage of the TV displaying a 3D image appeared in 3D on my TV, without the need for glasses. What this shows (and, indeed, what projecting any 3D image on to a 2D surface shows) is that there must be a way of making a true 3D image on a standard CRT. Maybe the computational power is too much right now, but I can't help thinking that if you can get an image that looks 3D on to a flat surface, there has to be a way to display one on a monitor, without any special hardware.
    • there must be a way of making a true 3D image on a standard CRT. Maybe the computational power is too much right now

      Viewing 3D means that each of your eyes sees a different image. You can't do that on a standard CRT no matter how much computer power you throw at the problem. If you go to the linked site, on of the first things he does is explain how we see 3D.

      -
    • To be able to view 3D images without 3D glasses is crucial to the success of such a system, especially if it is to be marketed to consumers.
      I don't think you are right. It's just an extra bit of hardware, like a mouse or kbd. The important thing is 3D images. As I said in a post below, these systems are used to view 3D models. Faking 3D from 2D images is something completely different.

      if you can get an image that looks 3D on to a flat surface
      Have you ever seen a movie? Doesn't it look 3D? Perception of 3D from 2D images is known since the renaissance with methods such as perspective. What you want is a real 3D model from a flat source. Then you have to estimate the respective distances between every points on an image and extrapolate what is on the other side of objects, ... Too difficult and intractable. How do you know you see a small tree from close or a large tree from far?
      • I don't think you are right. [3-D glasses are] just an extra bit of hardware, like a mouse or kbd.

        The biggest problem with polarized or shutter glasses, as I understand it, is that there's enough "leak-through" of the other eye image to damage the 3-D illusion.

        Head-mounted displays have no problems in this respect, but have the problem of making the focal distance far enough away from the viewer that they don't cause eye fatigue or destroy the illusion of distance to the objects.

        Have you ever seen a movie? Doesn't it look 3D?

        Apparently the video release of "Gosford Park" used some sort of post-processing on its images to try to enhance the 3-D feel of the movie. I watched it and can't say it really jumped out at me, but I would have liked to have seen split-screen or before and after demonstrations of the effect to get a better sense of what it did and how effective it was.
    • Bizarrely, the footage of the TV displaying a 3D image appeared in 3D on my TV, without the need for glasses

      So - when you moved from one side of the TV to the other it looked different? Did it?

      No.

      It didn't did it!

      doghty at school used to tell us his dad had a 2 wheel drive motorbike. Your not doghty are you???

  • Didn't someone do this in 1996? (Score:3, Informative)

    by reachinmark ( 536719 ) on Thursday September 05, 2002 @08:11AM (#4199489) Homepage
    Actually, I know they did: The Wedge [anu.edu.au]. A much more immersive version of it too. Granted, the wedge uses the expensive Crystal Eyes glasses for stereo instead of polarised glasses/projectors, but the basic principle of cheap VR is the same. Why don't people who set out to make a cheaper better solution start by doing a bit of web surfing!?

  • Cost-cutting (Score:2, Informative)

    by SablKnight ( 205665 )
    I found it interesting that they would pay ~$500 for a cart, ~$100 for a surge protector, and then be blocking up the projectors with dry erase markers and holding them in place with nylon straps. Some more careful management of budgets could probably bring this project in under $10K.

    SablKnight
  • hrm. I'm about 8 years out of the classes where I could have calculated this, but doesn't diffuse reflection (as used in projection) destroy polarization?

    I had assumed that these guys used alternating l/r images and synced them up with lcd shutter glasses, but apparently not!
    • Diffuse reflection does destroy polarization, for the most part. That's why polarized sunglasses are good for reducing glare. The diffuse image passes through with no problem, while the specular reflections from things like the surface of water tends to be polarized. Orient the polarization of the glasses in the opposite sense and voila! No glare.

      You need special screens with a specular or "somewhat specular" surface to get good 3D using polarization.

      These aren't that hard to find, though. They have higher "gain" than a normal diffuse screen, which makes the image brighter. The disadvantage is that the viewing angle is somewhat restricted (no free lunch).

      I suspect that's also why these guys specify DLP projectors rather than LCD. The light from LCD projectors (or screens) tends to polarized in its own right, which would mess things up unless you took special precautions.

      The CAVE system I've used uses LCD shutter glasses rather than polarized glasses, and will thus work with LCD projectors.
      • I'm certain that the CAVE you used was not using LCD projectors. There is no current LCD projector that is capable of active stereo. Also the polarizers in the glasses would interfere with the polarizers in the LCD projectors. LCD shutter glasses have the same sort of polarizers as the passive polarizing glasses.
        • I'm certain that the CAVE you used was not using LCD projectors. There is no current LCD projector that is capable of active stereo. Also the polarizers in the glasses would interfere with the polarizers in the LCD projectors. LCD shutter glasses have the same sort of polarizers as the passive polarizing glasses.

          Not necessarily. The viewer watches the screen, not the projector. As long as the screen is diffuse the polarization of the LCD projector will be destroyed, and can thus be repolarized by the LCD glasses. I'm not sure what you mean by active stereo though; are you saying that no LCD projector is capable of switching images on each frame (ie switching pixel states 60fps)?

          • If your screen perfectly depolarizes the light, then you're right. Most screens do let through some amount of polarized light, though. You'll see color shifts as you tilt your head when looking through LCD shutter glasses at the image from an LCD projector. When you're using shutter glasses it's called active stereo because the glasses are actively blocking and unblocking each eye. Passive stereo is when your glasses are just chunks of plastic. In order to do active stereo you need a projector that has a vertical refresh of at least 96 Hz so that each eye can get 48 Hz. LCD projectors can only refresh at 60 Hz, so each eye only gets 30 Hz which isn't nearly enough (lots of flicker).

  • Is it useful though? (Score:3, Insightful)

    by bluGill ( 862 ) on Thursday September 05, 2002 @09:26AM (#4199931)

    Sure this is cool, but is it useful? 2D screens are old hat, and seem to work well. People play doom and other 3d games on them without problems, so we can fake the 3rd dimention if we try.

    I can't be the only person who gets sick watching 3d films. I've only done it a few times, but that is enough that I refuse to considering doing it again. If 3d films become a major part of education, then I'm disabled because I cannot watch them.



  • ahh...this reminds me of 10 years ago when I hacked an Amiga Video Toaster to record interleaved 3D video from 2 cameras and play it back through LCD shutter specs.

    Those were the days...

  • The $10K setup described uses polarized projection, which is pretty good but requires a straight optical path. To make a 6' image you need 8-10 feet of throw distance - no mirrors allowed. A full wall (8-10ft) requires even more (I dont have the ratio handy, see projector specs). Front projection means you can cast shadows on the screen, which might be used for tracking/interaction but interfere with the 3d immersion/presence effect. Multi-walled setups require a LOT of space - or active stereo, which means more expensive projectors ($50k+) and gen-lock sync between video sources (not available for nvidia, ati, matrox 3d cards - sorta see links below)

    Tracking is another big problem left out in this implemenation. Mag trackers mentioned in another comment are one solution, although the interference problems are a big pain. My choice is the Intersense IS900, but it starts out at around $20k.

    For more on low cost immersive projection environments see Dave Pape's course notes [resumbrae.com]

    For more info check out my Siggraph2002 report [isdale.com] and my vr info site [isdale.com]

    Jerry Isdale

  • My college had mobile projection systems somewhat like what you describe and a bunch of them were stolen last semester. Evidently their compactness and cost makes them a hot item. (" 'scuse me, young man, could you show me what is making such a large lump under your jacket? ")

  • $10k? Bah!

    Drew Olbrich has a much better idea [traipse.com]. Nothing like 3D Asteroids!

    - grue

  • Try it with NO hardware... just crossed eyes (Score:3, Interesting)

    by Goldenhawk ( 242867 ) on Thursday September 05, 2002 @10:45AM (#4200356) Homepage
    No kidding. Start with this picture [simusic.com] (JPEG, 144Kb) of me on vacation last year. Now position your head squarely in front of the monitor, about 24" from the screen, and cross your eyes slowly until you see three pictures - the center one will be in stereo.

    This is rather like the random-dot stereograms, but inverted left/right from that arrangement. In the RDS, you RELAX your eyes, the opposite of crossing them. I personally find this difficult, so I swap the images so crossed eyes produce the correct left/right arrangement instead.

    Incidentally, I used to fly Microsoft Flight Simulator back in 1988 this way - yes, version 1.0. I discovered that I could set two different forward views from the Chase Plane mode, with one plane offset slightly to the right and the other slightly to the left. By properly arranging the windows and crossing my eyes, I could fly around looking at the simulated world in true 3D. I believe you can still do this with the different window options available in Flight Sim, and you could probably do this in any game that allows you to set up multiple windows from different viewpoints.

    Now, granted, it is tough on your eyes, and it's kind of hard to see any non-stereo items (like the control panel), but it IS 3D and requires NO hardware. From time to time I do this for other purposes - like the picture above.

    You can also do this with any camera if you have a still (or mostly still) subject - take a photo, move sideways about four inches and take another. Then load both photos into your image editor of choice, position them side-by-side with the proper left/right orientation, and you're set.

  • Tho I may have mispelled it. It's a mini-cave system, complete with tracker and small enough to fold into a crate for shipping.

    CAVEs can also be shipped. Setup and teardown time is pretty harsh but it can (and has at NCSA/UIUC) been done.
  • Hey,

    "This summer I helped built a Geowall stereoscopic projection (3D) system for the Southern California Earthquake Center."

    Do you need any help to test your 3D Quake Simulator? If so, call 1-800-GAMERSINC

    Thanks,

    Michael
  • The basic idea is sound, but if you want a really cheap 3D projection system, use a couple of old LCD projection panels + overhead projectors. You can find a lot of these things on Ebay. Proxima made the best ones AFAIK. Overhead projectors are big and heavy so you might want to look at a local auction instead. So now, you're looking at a cost of perhaps..

    100x2 lcd panels
    50x2 overhead projectors
    30-50 quality polarizing filters
    5ea polarized glasses
    50 old silver screen
    150 dual-head radeon 8500

    Around $500-600. Much better. Now it's truly a 'poor man's' 3D projector. And to think some people would spend that much on a 32" television!
  • It's been tried before, and done. The real problem is that an ideal stereoscopic projection is different for each viewer - it depends on the distance between the eyes. It's also difficult for an individual to judge when a stereoscopic projection is properly calibrated to their vision.

    And if it's not properly calibrated, within half an hour, you have a real killer headache. Combine that with the fact that we are already really good at picking up 3-d visual information from 2-d projections, and I don't see this going much of anywhere in the near future. Especially at $10k.
  • From MS Manual of Style v3.0:

    comprise

    Avoid in general, mostly because its meaning is often confused. It means "include" or "contain." Depending on your meaning, use those terms or consist of or make up as appropriate. Do not use comprised of.
  • Has anyone produced a left-eye/right-eye differential version of DOOM?

    Because 10k for stereoscopic DOOM is well... within the realm of daydreams at the very least!
  • Now I could be wrong but as I understand the writeup the user is using a rather expensive converter to send the images to the projectors. Couldn't a Linux box with two xservers running and 2 video cards (or two linux boxes run by a master system, a mini cluster) do the same thing for under 4000?? I am not a Linux Guru by any streach of the imagination. But if that worked it would be a heck of a lot cheaper then the 12000 buck converter.
  • OK...projector maker type folks...here's what I dream about...

    Take one of those 3 DLP projectors; remove one of the panels; make the remaining 2 panels full function color; and then put high-efficiency polarizing filters or splitters/combiners (preferably circular) into the internal projector path.

    Now we would have a fully pixel aligned, efficient, single-box, passive stereo projector that could turn into a mass-produced item for us all.

    Then do this for native 1920 X 1080 DLP chips...ASAP.

    Would be sweet!

    MJR

    PS...More Geowall assembly instructions can be found at the eMedia Center Geowall/AGAVE Development Project site [wisc.edu]

  • It seems that, tho I like what they did, it could have been better.

    The problem with the "no software implementation" for sending the images to different monitors? Tho still grounded slightly in hardware, wouldn't it have been easier to just use two cards?

    And, tho i understand they can afford it, when I get around to trying this out, I'm making the projectors myself! A nice google search tells you all you need to know.

    The first point I made solves this one: they didn't need to do so much image editing. Not to mention, aren't the image files timestamped? That should help with the ordering... And most camera software lets you specify filename prefixes.
    • The latest NVidia cards (700, 750 and 900 XGL...not sure if it works with the really cheapo 550 XGL) all support "Native" dual projector passive display for OpenGL applications using just one card under Windows (not available for Linux yet). And it is very high performance. So far, it requires "standard" OpenGL Crystaleyes apps to work (like GL Quake). Hopefully, Nvidia will someday put their "Clone" mode support into their stereo gaming driver as well.

      When building your own projector, make sure that you use methods that allow you to control polarization. LCD projectors can cause considerable problems for this. We use DLP projectors.

      Here's more info on Windows setup for Geowall stereo projection in OpenGL with nVidia cards [wisc.edu](pdf file)

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