[Chimera-users] Fwd: Re: 3D stereo

Dougherty, Matthew T matthewd at bcm.edu
Fri Nov 19 15:44:35 PST 2010

Hi Nadir,

We have a early DepthQ.  The screen is about  ~three  meters wide, which is limited by the height of the room.  I would suspect we could go bigger.  We can pack 30 people in our conference room.  We have been doing stereo for 15+ years.  The limiting factor we have seen is the cost of stereo glasses, originally $1k each & now at $300.  If you are going beyond 5 people a polarizer with passive polarized glasses is the way to go.  Unlike the Zalman and other monitors where you loose 50% of your vertical resolution, the DepthQ will give you full resolution because it buffers the LR frames.

The big problem we have seen with stereo is implementing it correctly.  Just like color blindness, a fairly large percentage of the population just does not get it or barely gets it; but unlike colorblindness tests which most people are familiar with the concept and their personal results, stereoscopic vision ability is not normally measured or discussed, so most people are clueless about their ability or inability.  Optometry stereo tests are available and not difficult to use, they require no batteries or equipment.

Beyond this, actually producing stereo imagery has some tricky hurdles.  Stereoscopic effect is a macular phenomena, which occurs at the center of vision about the size of a baseball at arms length or the moon on the horizon.  In the real world the stereo zone is constantly moving as we move the focus of attention.  For one or two people exploring a dataset on a monitor, making these adjustments can be done (but could be significantly improved through better interfaces to stereo control parameters, like a knob on binoculars).  But for a large crowd, this interactive ambiguity can be a major liability, consequently a choreographed animation is needed.  

GREG- correct me if I am wrong here: using reset to change from keyframes does not change the stereo values, so this is a tricky problem in getting the stereo to change during the animation.

Consider this, in the movie Avatar the stereo effect is weak and strong, depending on the focus of the storyline.  Through out the movie, there is stereo, no stereo, strong stereo, weak stereo, no stereo, etc.  The common problem in presenting to conference room crowds is the mistake of turning on the stereo, setting the parameters once and you are done.  To make it work effectively you have to dynamically change those parameters in a way that guides the audience to what is being revealed.  One size does not work, you have to make it work for the people in the front of room optimally, then adjust the effect for people in the back of the room to see it optimally.  It is the dynamically changes in the brain that accentuates the effect; too fast and you confuse the audience, too slow and they are bored.

From: chimera-users-bounces at cgl.ucsf.edu [chimera-users-bounces at cgl.ucsf.edu] On Behalf Of Nadir T. Mrabet [Nadir.Mrabet at medecine.uhp-nancy.fr]
Sent: Friday, November 19, 2010 11:14 AM
To: Greg Couch
Cc: chimera-users at cgl.ucsf.edu BB
Subject: Re: [Chimera-users] Fwd: Re:  3D stereo

Hi Greg,

Both DepthQ and Christie (made in fact by the same manufacturer. http://www.depthq.com/projector.html; http://www.depthq.com/christie.html) are, as expected, sold in France by a unique firm.
They say that DepthQ HDs3D-1 ($2,995) has no capability for 3D for a conference room with 30-50 people, and that my only option is Christie (> $65,000!).
Your earlier mail states that DepthQ can go along with a 3-meter size screen, suggesting it could accommodate an audience of 30-50 people.
Can you, please, comment on all these issues and eventually let me know if I can go along with DepthQ DLP?
Many thanks in advance.



Pr. Nadir T. Mrabet
Structural & Molecular Biochemistry
Nutrigenex - INSERM U-954
Nancy University, School of Medicine
9, Avenue de la Foret de Haye, BP 184
54505 Vandoeuvre-les-Nancy Cedex
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E-mail: Nadir.Mrabet <at> medecine.uhp-nancy.fr
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On 28/09/2010 12:59, Greg Couch wrote:

Subject:        Re: [Chimera-users] 3D stereo
Date:   Tue, 28 Sep 2010 12:59:13 -0700
From:   Greg Couch <gregc at cgl.ucsf.edu><mailto:gregc at cgl.ucsf.edu>
To:     Nadir.Mrabet at medecine.uhp-nancy.fr<mailto:Nadir.Mrabet at medecine.uhp-nancy.fr>
CC:     Chimera-users at cgl.ucsf.edu<mailto:Chimera-users at cgl.ucsf.edu>

 On 07/21/2010 07:24 AM, Nadir T. Mrabet wrote:
> Hi,
> This is for teaching purposes so that students can "walk" though 3D structures. Would it be possible to use Chimera via a 3D stereo beamer to project display on a very large screen and watch the selected structure in 3D by means of shutter glasses?  If this is so, what kind of equipment would you recommend?
> Many thanks,
> Nadir

So there were some developments at SIGGRAPH, but nothing that would
change the previous recommendations made in the chimera-users mailing list.

To summarize, for a large group of people, you want a setup similar to
what is done for 3D movies in a movie theater, which is to use left-hand
and right-hand circularly polarized light for the left-eye and right-eye
images.  There are three parts to the setup: (1) projecting the stereo
images, (2) reflecting the images, (3) receiving the images at the eyes.

1. For projecting the stereo images with chimera, you need a
workstation-class graphics card, either an AMD FirePro (or ATI FireGL)
or a NVIDIA Quadro (or Quadro FX, not Quadro NVS), and either (a) two
projectors with passive polarizers, or (b) a single projector with an
active polarizers.  The single projector method is much simpler to
maintain because you don't have to keep aligning the two projectors, but
may cost more because the projector has to be able to display at 120Hz
(and there's the cost of the active polarizer).  The relative costs of
the two options vary.  Active polarizers are available from DepthQ,
http://www.depthq.com/, and RealD,
http://www.reald.com/Content/professional.aspx.  DepthQ also sells a 3D
projector that can display 3 meter wide images, and has European
distributers, so that might be the best choice.  If you want a larger
image, you'll need a Christie Mirage or a Barco projector.

2. To reflect the stereo images, you need a screen that doesn't change
the polarization of the light.  There are lots of choices.  Google for
"3D projection screen" to see what's available.  What screen you want
depends on the layout of the room that the stereo projection will be
in.  Narrow rooms can use screens with a smaller viewing cone and higher
gain.  I've heard good things about Stewart Filmscreen, but get
recommendations from whoever you buy your projector too.

3. Last part of making sure each eye only receives the image it is
supposed to is for the person to wear circularly polarized glasses.
Google for "polarized 3d glasses" to see what's available.  I'd avoid
the disposable paper ones.  I like the RealD glasses that the movie
theaters use.  Perhaps a theater would sell some to you.  The glasses
from Zalman displays work too.

    Bon chance,


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