jbn@glacier.STANFORD.EDU (John B. Nagle) (01/31/89)
Clearly the next step after HDTV will have to approach Showscan
resolution. We are also going to need computer displays with that kind
of bandwidth. How much bandwidth is it? Well, a 70mm film frame is
generally considered to be about 6000 by 8000 pixels. So 60fps x
256 levels x 3 colors x 6000 x 8000 = 2.2*10^12 bits/sec, or an
uncompressed data rate of about two terabaud. Hardware with this
kind of speed should be achievable by 1995 or so.
For flight simulators and such, one really needs an image that covers
a hemisphere. What fraction of a sphere is Showscan?
The amount of compute power necessary to generate high-quality
images in real time at these densities will be rather large. If we
take a goal of obtaining the quality of Pixar's "Tin Toy", and want a
hemispherical view, how much compute power will be required, and,
based on projections that progress continues at current rates, when do we
get it?
John Naglecraig@hp-lsd.HP.COM (Craig McCluskey) (02/01/89)
> How much bandwidth is it? Well, a 70mm film frame is generally considered > to be about 6000 by 8000 pixels. So 60fps x 256 levels x 3 colors x 6000 x > 8000 = 2.2*10^12 bits/sec, or an uncompressed data rate of about two > terabaud. 256 levels = 8 bits therefore, 60 x 6000 x 8000 x 8 x 3 = 6.9 E 10, or 69 gigabits/sec Craig
myers@hpfcdj.HP.COM (Bob Myers) (02/01/89)
> Clearly the next step after HDTV will have to approach Showscan >resolution. We are also going to need computer displays with that kind >of bandwidth. How much bandwidth is it? Well, a 70mm film frame is >generally considered to be about 6000 by 8000 pixels. So 60fps x >256 levels x 3 colors x 6000 x 8000 = 2.2*10^12 bits/sec, or an >uncompressed data rate of about two terabaud. Hardware with this >kind of speed should be achievable by 1995 or so. However, I strongly suspect that we will *not* be seeing the computer graphics industry moving toward this resolution; it simply will be too difficult to get the display device itself at a reasonable cost, at least in this timeframe. If you're talking color displays at 1k x 1k or higher, you are by necessity talking about CRT-based displays. An 8k x 6k display, even with a 0.20 mm dot pitch, would require a tube approaching 2 meters on the diagonal; finer dot pitches would make the tube smaller, but probably are not achievable anytime soon. (And it still wouldn't be THAT small - care to work out the numbers for 0.15 mm or even 0.10 mm dot pitches?) For that matter, how much resolution is usable? A 4k x 3k image, on a 19" tube, gives around 300 dpi, and is already comfortably beyond the color resolution limit of the eye. I suspect that something in this range will be the limit for "desk-size personal workstation" displays, especially in color. ShowScan is nice, but don't forget that it IS for the "big screen"! (One other frightening number to contemplate - the video clock for a 8k x 6k, 60 Hz non-interlaced display!) Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other {the known universe}!hplabs!hpfcla!myers | sentient life-form on this planet.