Enhanced Chemistry Education via 3D Projection
What we hope to include on this page are more specific details, the expected problems, the unexpected difficulties, and the work arounds that we experienced.
| Item |
Challenge |
Comment |
| 11 | New computer system for lecture hall (November, 2003) | Dell, Precision 360 MiniTower with 2.40 GHz/800 FSB, P4, 512K Full Speed Cache, 1GB, 400 MHz SDRAM (2x512), nVidia Quadro FX 500 128MB dual VGA Grapics card, 80 GB HD, Floppy drive, 48X CD-RW/DVD combo. |
| 10 | New System Configuration | In September 2003 we completed the setup of the new system. This utilizes a Quadro XGL card and Quad Buffered Clone mode (which should be compatible with any "OpenGL Stereo" software) to solve many of the problems we had before. The Cyviz is no longer necessary, greatly reducing the overall cost of the system. Problems The Wildcat card abruptly ceased to work properly in older system - Windows refused to recognize it as anything beyond a "Standard VGA card". It has been RMAed back to the manufacturer for inspection and possible repair. We use a video splitter to alternate from CrystalEyes stereo to Projector (Quad Mode) stereo. This involves changing the "OpenGL Stereo Mode" in the nVidia drivers. However, CrystalEyes works best with a high refresh rate (>=100hz), and switching it back to Projector mode while using the high refresh rate will cause mysterious problems such as one projector not working, both not working, or bizarre artifacts. Solutions Always reduce the refresh rate to 60hz or 75hz when moving from CrystalEyes to Projector stereo mode. |
| 9 | New Computer System | In November, 2002, we upgraded to a new
computer for the "Portable 3D System" and have learned some things. System: Generic system with a Athalon Processor (? GHz), ??MB memory running X, GeForce 2 card, hacked driver. Problems with the above: Motherboard does not contain a slot that can accommodate the Wildcat graphics card. The two JPS Viewers we tried (Open GL JS Stereo Viewer 1.0 by M. Husak, staff.vsch.cz/~husakm/ and the one that came with a GeForce card (??) both WORK with the shutter glasses, but DO NOT WORK with the Cyviz. Solutions in progress: |
| 8 | 3D Polarized Glasses | In Sept '01, we order 100 "Paper 3D glasses" and 30 "Plastic 3D glasses". Even though polarizers are configured so that the paper ones worked regardless of how you folded them, we found them to be too flimsy for use more than 3 or 4 times. |
| 7 | First public demonstration | Everyone involved in the project design were very impressed with the 3D capability; even when you know what to expect, the experience is quite impressive! [12/6/01] |
| 6 | Silvered screen | We ordered a Stewart AT2M266CSLV3D
screen, with "Silver 3D-(0")" sreen material and an
image size of 13-ft by 18-ft (225-ft-2.5-in diagonal) with an aspect
ratio of 1.38:1 and a 14-ft by 19-ft frame.
The instructions that come with the silvered screen warn not to touch the surface. It is absolutely necessary to warn your installation people not to touch the surface or to let anything else touch it, or if something comes in contact with, not to compound the problem by "wiping it off". I can assure you that handprints are easily viewed, that dropping the screen against the scaffolding puts permanent marks on it, and that attempts to rub out dirt by the installers leave noticeable imperfections. [1/8/02] REMEMBER: Always use white gloves, and if you shall reinstall the screen, never fold it, but cover the surface and roll it around a tube! 4/25/02] |
| 5 | Overlapping projector outputs | Our A/V engineers did quite a good job overlapping the displays of the two projectors; however they are not perfect. If one projects the "desktop", usually one corner, at least, of the dual images, is noticeably not overlapped. This limitation requires that we configure the lecture hall projection system such that only one projector be used, without the polarizer for PowerPoint (and such) presentations. Initially we had anticipated that both projectors would always be on, through the polarizers, regardless if a 3D image was being shown, or just a normal image - that expectation is not longer reasonable. [1/8/02] |
| 4 | Cyviz location | Our house PC is approximately 150 ft from the data projectors, so the question arose as where to mount the Cyviz, close to the projector or close to the computer. Since a serial cable connection between the Cyviz and the House PC is necessary, our initial feeling of putting the Cyviz next to the projectors was scrapped and we have the Cyviz next to the house PC and run two separate signals to the data projectors (luckily for us, during our recent renovation, we had requested and received wiring for sending output from the front of the lecture hall to two different data projectors at the back!). We don't know if we could have spliced a long serial cable in for the Cyviz control, or whether that cable length is limited. [1/8/02] |
| 3 | Cyviz limits portable use | Our initial lecture hall configuration was such
that all computer outputs from the lecturer were sent through the Cyviz to
the two projectors. In the event that 3D was not being used (i.e.,
if a normal PowerPoint presentation was needed), one of the projectors
would be manually blocked (or turned off), and the polarizers remotely
removed from in front of the lenses. However, we found that some
portables PCs that work quite well with the Sharp Projector directly, do
NOT work when their monitor signal is first sent through the Cyviz.
As our lecture hall is expected to be used by lots of different people,
many of whom will bring their own portable for their powerpoint
projections (but use our House PC for the 3D), we found it necessary to
rewire such that only the House PC output goes through the Cyviz and the
portable bypasses it. [1/8/02]
(Cyviz's note: Most projectors will not allow lower than 45 Hz input signal. Try as follow; Make sure that the output signal from your PC is more then 96Hz, or set the output signal to 60Hz (then the output also will be 60Hz). |
| 2 | Aging of lamps | We have discussed whether the lamps in the two projectors should "age" at the same rate. In other words, if one lamp is sufficiently brighter than the lamp in its mate projector, will that impact the 3D projection. Initially we decided that both projectors should be on, if one was used (i.e., that the bulbs should always have the same amount of usage); but currently we don't feel that way anymore. Our lecture hall is currently wired such that only one power on/off control is available which means we are slaving the second projector to the first and that both projectors are either on or off. [1/8/02] |
| 1 | Polarizers Melted | Because the polarizers provided by Cyviz are
only ? in sq, we were worried that they might be too small for the light
beam. So, initially, we had our machine shop fabricate aluminum
holders that fit onto the lens of the Sharp Projector. The plastic
polarizer was then taped to this aluminum piece and the piece held to the
lens with a set screw. While this worked well, and allowed the light
beam to completely pass through the polarizer, we found, after maybe 5-10
hours of projector use, that the plastic polarizers had noticeably warped
in their very center. [1/8/02]
We are now looking to buy glass polarizers, and will fabricate a motorized "wheel" that will allow the lecturer in the front of the lecture hall to select a wheel position such that the polarizers are in front of both projectors, or another position such that only the light from one projector is passed through (no polarizer) and the second projector's output is manually blocked. We ended up buying polarizer film from Edmund Industrial Optics (see previous web page), and had our wonderful model shop staff build a slider to move the 9-inch square polarizers (about 5 inches in front of the lenses) in and out of the light path, and our talented e-shop staff building a remotely controlled motor to actuate the movement. There are four different ways to installed the "pair of crossed polarizers" (<, >, V, ^); by trial and error we had to explore three of these before we had them matched to the glasses (i.e., you need the left eye data projector mated to the same polarizer as the left eye of the glasses). If the data projector polarizers are off by 45 degrees from the glasses orientation, dramatic color shifts are obvious; if the polarizers have the correct orientation, but are mismatched with respect to eyes, the "images" are obviously "confused". [4/25/02] Cyviz sells a set of 4x4 and a set of 5.5x5.5 linear polarizer lens (but each pair costs more than a $100). |
Site maintained by: Joe Grabowski, joeg@pitt.edu
Last updated:
13 December 2003