Received: from watserv1.uwaterloo.ca (watserv1.waterloo.edu) by karazm.math.UH.EDU with SMTP id AA29626 (5.65c/IDA-1.4.4 for ); Wed, 23 Oct 1991 22:26:13 -0500 Received: by watserv1.uwaterloo.ca id ; Wed, 23 Oct 91 23:22:02 -0400 Date: Wed, 23 Oct 91 23:22:02 -0400 From: Dave Stampe-Psy+Eng Message-Id: <9110240322.AA17551@watserv1.uwaterloo.ca> To: glove-list@karazm.math.uh.edu, newton@neworder.ils.nwu.edu Subject: Re: Transputers... > From glove-list-request@karazm.math.UH.EDU Wed Oct 23 21:13:53 1991 > From: newton@neworder.ils.nwu.edu (Dave Newton) > Subject: Re: Transputers... > To: glove-list@karazm.math.uh.edu > > In a previous message, Dave Stampe-Psy+Eng said: > > Actually, VPL is just sending world database updates by Ethernet, which > > is OK. But we're talking about sending rendered pixels to the video board, > > which, for a 500x500x24 bit picture, needs 6 Mbits/sec times the frame rate! > > Can the video board handle this data rate??? If ypu use 4 transputers, can > > they SEND this rate??? For our purposes, I think the world database > > could reside on one transputer, which does preliminary clipping and > > sends polygon and attribute lists to the other transputers. IF the > > video board can handle the input speed, this idea will work. But not > > if you have to design a custom video buffer... Or, how about using > > 4 video boards, genlocking them, and switching between them as their > > video segments occur??? > > Each set of transputers that is doing rendering would have a copy of > the world in it, so theoretically all it would have to do is blob-move > that memory into whatever yo uwere using for output. If I'm going the > cheap eye-phone route, I'll probably not have 500x500x24 in the near > future. > > Why??? A fair amount of the work involved in the preprocessing of the world database (especially if you're using an object-oriented tree or a BSP algorithm would then have to be done on each processor... needless repetition, with little load involved in the transfer from the central world-list handler you'd need. And the data rate to the central video board is STILL too high... 320x200x8 bit video, 20 frames/sec is 11 Mbit/sec, with no margin for peak loads, repetitive writes to any pixel, etc. Unless you are using a PARALLEL interface... As you can see, it's borderline. And for the cost of the Transputers and the video buffer, I'd like to get something good for my money. Not that I believe it's impossible, but I'm working without the transfer specs, and prefer to err on the side of caution. (B-{) So... can you post the transfer specs on the video card, prices, etc. I AM interested, just cautious. It would be great to be able to put together a 10Kpoly/sec system with Gourand shading, textures, GOOD color, stereo video (2 outputs) and 20 frames/sec for under $1500 extra... - Dave Stampe