galt@dsd.es.com (Greg Alt - Perp) (05/20/91)
Apparently biggest expense was just the display and position
tracker. The display was $1500 (2X$750) and the position
tracker was $3000. The voice input isn't too important, and
could probably be done with a soundblaster card for only $150.
The glove is very cheap, but the interface is ugly.
In the paper, they said that resolution wasn't important and
that 320x200 is good enough. They also said that stereo wasn't
necessary. This being the case, wouldn't it be easy to use a
cheap ($100-$200) lcd display and hang it in front of someone's
face? Then, it would be necessary for some sort of position
tracker. I still think that a power glove mounted backwards on
the head would be a cheap alternative. It apparently has high
enough resolution, but possibly too big of a lag. I would be
willing to settle on the more limited movement (and even the lack
of up/down head rotation).
A system like this would cost between $300 and $500 which is less
than $.50 per day for 3 years (less than many students spend on
video games).
(also, I think that it would be unecessary to get an 80387 since
the matrix manipulation could easily be done with fixed point
math using the fast 386 integer math)
Greglance@motcsd.csd.mot.com (lance.norskog) (05/21/91)
3rd-party 8514 cards are now $500 here in Silicon Valley. They should be fast enough to do animated displays, and include painter's algorithm polygon fills. E.g. you copy from bitmap A to bitmap B, the chip uses an outline in rectangle C to decided when to actually write in B. The problem with 8514 is the chip sets that I've studied don't support low-resolution clocks; you can do full-color with one buffer, 16 colors with dual-buffer screens, and no quad-buffering. Stereo VR needs quad buffers, two for display and two for drawing the next frame. The most interesting card I've seen is from Antex in Gardena, CA (213-xxx-xxxx). For $900 you get VGA, NTSC, stereo 12khz 14-bit sound, 1mg RAM, and a TI DSP chip. With an assembler loop on the TI doing sound management interspersed with drawing from a 2D display list, and a 386 feeding it the 2D display list and sound start/stop/position commands, you could do a really nice low-end VR system. As for tracking, this Polhemus stuff is for the birds. It should be easy to put a few ultrasonic or infrared transmitters in the corners of the room, and place 2 receivers each on your head and hands. You've already got a wire bundle feeding the glasses, more wires from the receivers is fine. PC lab cards that could read these are $200-$400. If all the transmitters transmit at different frequencies, you can just pull the frequencies out with a multiple notch filter circuit and feed those into the lab card A-Ds. You already have a 386/387 (or in my case a 486-33, smirk) for doing transforms. You have to decide which signals are are obscured or reflected, build XYZ for all receivers, then extract roll/pitch/yaw from the receiver-pair deltas. You need to build a model for dealing with reflections of your ultrasonic/infrared transmissions. Ray-tracing has been used in this modeling domain. You're welcome to build and sell from these ideas. I want one and I flunked electronics. Lance Norskog
lowry@SRC.Honeywell.COM (Dave Lowry) (05/23/91)
In article <1991May21.011155.15840@milton.u.washington.edu> lance@motcsd.csd.mot .com (lance.norskog) writes: > >3rd-party 8514 cards are now $500 here in Silicon Valley. They > >The most interesting card I've seen is from Antex in Gardena, CA >(213-xxx-xxxx). For $900 you get VGA, NTSC, stereo 12khz 14-bit > I've been working on a *very* cheap system. I just finished a board (4 x 7 in) that will generate modest wireframe stereo images at 256 x 192 pixels. Update rate is 30 Hz. for each eye. Total cost was about $75, not including a DSP chip I borrowed. Assembled the thing in my spare time, in my basement, using mostly scrounged parts. Yes, the resolution is real low, but most TV LCDs are only a little better (300 x 200 ?), I think. And yes, it's not sexy Gouraud-shaded polygons in 16.7 million colors, but this is something you could slip into a coat pocket. Beats carrying two Personal IRISes on your back :-) Don't have a tracking system yet, but RS-232 is on the board, so I could plug into a Polhemus, I think. Anybody want to lend me one?