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From: uselton@nas.nasa.gov (Samuel P. Uselton)
Newsgroups: comp.graphics
Subject: Re: Digital Holography
Summary: Not soon, MORE FLOPS needed
Message-ID: <1991May10.165256.12414@nas.nasa.gov>
Date: 10 May 91 16:52:56 GMT
References: <1991May7.215514.6676@csl.dl.nec.com> <261@rins.ryukoku.ac.jp> <1991May9.153446.21742@leland.Stanford.EDU>
Sender: Sam Uselton
Organization: NAS Program, NASA Ames Research Center, Moffett Field, CA
Lines: 56

In article <1991May9.153446.21742@leland.Stanford.EDU> rick@pangea.Stanford.EDU (Rick Ottolini) writes:
>IMHO digital holography will be THE 3-D graphics technique of the future.
>Current rendering techniques SIMULATE 3-D through the using of lighting
>models, shape [perspective, stereo], and motion [fly-thru animation,
>virtual reality animation].  Holography seeks to compute actual light waves
>themselves.  
	As a tray racer, I mean ray tracer, I've thought a bit on this,
	and have a little experience too.
>I envision "Princess Lea" displays, floating images like that
>of the help message in Star Wars I.  This avoids the sensory sheaths the
>VR people are using.
>The mathematics of digital holography are fairly well known, but the computations
>are expensive.  
	Probably more than you realize.
>They are similar to other imaging mathematics such as my field
>of seismic imaging.  
	I've also consulted with "Big Oil".  Seismic imaging is more similar
	to image processing and scene analysis than to image generation
	techniques.  You HAVE the image, and are trying to guess the most
	likely scene which could have created it.   
>Even with all kinds of shortcuts thrown in, it will take
>billions to trillions of calculations per second to display interesting
>holographic images.  
	Current realistic image synthesis techniques can take from 100 million
	 to 1 billion operations per image.  Laser holography is AT LEAST
	a couple of orders of magnitude more.  And you still WANT the animation
	so add another one or two orders of magnitude.  I see trillions of
	operations per second as a LOWER bound on what it might take.
	The NAS project at NASA Ames regards pushing industry into producing
	a teraflops computer by the year 2000 as a "Grand Challenge" problem.
	It'll be quite a while longer before that capacity finds its way
	into workstations for the broad market.
>With the computing speeds increasing an order of magnitude
>every five years and no end in sight, 
	          ^^^^^^^^^^^^^^^^^^^
	There is a growing number of "experts" pointing out limits to current
	hardware techniques that we ARE rapidly approaching.  We need 
	BREAK-THROUGH improvements in technology, not just incremental
	improvements in the technology we have now.
>we are taking about the early 21st
>century for this capability.  
	Proof of concept maybe.  To get the image quality you want, the speed
	you'll want, and the cost to make it usable by someone other than
	national labs, I think it'll most likely be after 2030.
>The Popular Science article of last year equates
>the complexity of MIT Media Lab holo-images with 2-D graphics on oscilloscopes 30
>years ago.  So this technology is probably realizable in most readers lifetimes.
	Some yes. Most? That depends as much on health technology as 
	anything.
>As pointed out in an early posting, much work still has to be done in the
>display hardware, that is getting the numerical description of the light waves
>converted into light.
	That too.

Sam Uselton		uselton@nas.nasa.gov
employed by CSC		working for NASA (Ames)		speaking for myself