Ray Tracing News

"Light Makes Right"

June 20, 1988

Volume 1, Number 7

Compiled by Eric Haines erich@acm.org . Opinions expressed are mine.

All contents are copyright (c) 1988, all rights reserved by the individual authors

Archive locations: anonymous FTP at ftp://ftp-graphics.stanford.edu/pub/Graphics/RTNews/,
wuarchive.wustl.edu:/graphics/graphics/RTNews, and many others.

You may also want to check out the Ray Tracing News issue guide and the ray tracing FAQ.



So, I've regained the desire to type again a mere month after the SIGGRAPH course notes deadlines. Not much in the queue, but I thought I'd pass on what little there is. The most interesting developments which affect ray tracing are the release of the RenderMan (tm) interface by Pixar and the publication of Ardent's Dore' (tm) Programmer's Guide and Reference Manual.

Andrew Glassner's hardcopy "RT News" is coming out soon - if you're not on the mailing list, write him.

SIGGRAPH Ray Tracers Roundtable: in case you don't know, this is an informal get-together during SIGGRAPH where we talk about ray tracing techniques and trends. Personally, I'd like to aim for about the same time as last year: Thursday, sometime after 5 pm (with people then hitting the technical reception for food afterwards). Same as last year, we'll leave notes at the message center to all subscribers as to exactly where and when. If you're not planning to attend SIGGRAPH, please save me some note-writing effort by telling me. Otherwise, see you there.

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New People and Addresses

Paul Heckbert's summer address (at Xerox PARC):


Mail will still (slowly but surely) reach Paul at his old Berkeley address.

# David Lister
# Data General Corp.
# 62 T. W. Alexander Drive
# Research Triangle Park, NC   27709
# (919) 248-6223
alias	david_lister	hpfcrs!hpfcla!hplabs!lister@dg-rtp.dg.com

From David:

I have been working on Ray Tracing since 1984 while I was a graduate student at The Ohio State University. I am still working on my thesis for my MSEE on parallelism and algorithm improvements for Ray Tracing. My areas of Ray Tracing interest include the following:

1). algorithm efficency 2). simulation of natural phenomenon (optical characteristics of materials)


3). parallelism.

David Lister

# Pete Segal
# AT&T Pixel Machines
# Room 4K-208
# Crawfords Corner Road
# Holmdel, NJ  07733
# (201)-949-1244
alias	pete_segal	hpfcrs!hpfcla!ihnp4!homxc!pixels!pls

From Pete:

I'm not real big on introductions, but here goes...

I was born the son of a poor black sharecropper... wait, wrong story....

I started in the Computer graphics lab at RPI in 1979, got my Master's in '82 and came to Bell Labs doing graphics for CAD systems. I moved to Pixel Machines in early 1987 and have been working there since. I am interested in 3d rendering and animation, and I am currently working on the Ray tracing library for the Pixel Machine, RAYlib.

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Non-article on RenderMan and Dore', by Eric Haines

What follows is a non-review of RenderMan and Dore'. If you've been looking for a chance to contribute to the RT News, here's your chance - I'm not planning on reviewing either of these in depth, but would love to hear others' opinions (even anonymous ones) of these packages.

I just received a copy of Pixar's "RenderMan" interface. To quote the preface:

	The RenderMan interface is designed so that the information needed to
	specify a photorealistic image can be passed to different rendering
	programs compactly and efficiently. ... In order to achieve this,
	the interface does not specify how a picture is rendered, but instead
	what picture is desired. ... The RenderMan interface is a collection
	of procedures to transfer the description of a scene to the rendering

The interface for the ray tracer is wonderfully short, as it is simply another command in Pixar's shading language. I include it here in full:


color trace( point R )

	"trace" returns the incident light falling on a surface in a given
	direction R.  If a particular implementation does not support ray
	tracing, and cannot compute the incident light arriving from an
	arbitrary direction, trace will return 0 (black).

That's it. I don't see any way this command can support shadowing or filtering, but I haven't read through the document carefully (Pixar seems to want to go with their "Shadow Depth Maps" instead - SIGGRAPH 87 paper).

Anyway, this interface is "endorsed" by Apollo, DEC, Stellar, Ardent, and Sun, so it seems to be a happening something. I'm not sure what "endorsement" means, exactly, but one thing it means is that you should probably check it out.

Dore': well, I received the two preliminary manuals yesterday. As such, about all I can commit myself to is: "nice packaging - very artsy binders". Reviews, please?

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Ray Tracing Bibliography Update, by Paul Heckbert and Eric Haines

Paul Heckbert's "Ray Tracing Bibliography" has been updated for May, 1988. It will appear in the next issue of the hardcopy "Ray Tracing News" and in the SIGGRAPH '88 "Introduction to Ray Tracing" course notes. If you would like to see it before then, or would just like to have an electronic version on hand, please write Eric Haines and I'll mail you the latest version. Also, if you do get a copy, please tell us of any errata or addenda you may have for it.

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Commercial Ray Tracing Software, by Eric Haines

I'm collecting information for the "Consumer's and Developer's Guide to Image Synthesis" course at SIGGRAPH this year - namely, companies selling ray tracers. The bare bones info is at the end of this issue. I'm in the midst of ordering manuals, but that's about as far as I'm going. So, I would like to hear from anyone who knows anything about these packages. I will keep all reviews confidential, unless you explicitly state otherwise.

Below is a partial list of groups (in alphabetical order) offering ray tracing packages. If you know of any others, please clue me in (I'm particular ignorant when it comes to software for animators & advertising, such as Wavefront. For now, I have left them off the list below). The "Contact" section first lists the person who I have dealt with, followed by the official contact address and/or phone number. I believe the only company that won't have representation on the floor at SIGGRAPH is Ray Tracing Corp (though UCS probably will, in some form). Oh, just to dispell rumors, "Numerical Designs Ltd", Turner Whitted's company, is not planning on announcing a ray tracer by SIGGRAPH 88. Instead, they are marketing a package based on using pipes and filters for rendering (beyond this, I do not know...).

AT&T, Pixel Machines "RAYlib". Available only on the Pixel Machine.

	Cost: ???, manuals available realsoonnow.

	Contact: Ken Krause, 201-563-2274.
		 AT&T Pixel Machines

Ardent, "Dore'". Available on Ardent's Titan superworkstation. Source available in C, portable to other machines.

	Cost: $250 for universities, research sites.  $15000/$5000 per year
	for commercial sites.  Binary license $200 per copy.  Programmer's
	Guide and Reference Manual preliminary versions are $25 each.

	Contact: Ardent Computer Corporation,
		 880 West Maude Avenue,
		 Sunnyvale, CA  94086

Hewlett Packard. Add-on to their existing "Starbase" graphics package, which will also include radiosity software. Announced at NCGA 1988. Available with the TurboSRX come the end of the year (?).

	Cost: ???

	Contact: Hewlett Packard Co.
		 1-800-752-0900, Ext. 782A

Integra (via Mitsubishi, via Enimax), "Turbo Beam Tracing". Available on IBM PC/AT or compatible.

	Cost: ??? (will be shown at SIGGRAPH)

	Contact: Gregory Szewczyk
		 Enimax International Inc.
		 113 Martin Grove Road
		 Etobicoke, Ontario M9B 4K7

Ray Tracing Corp, "TRACER" and "TRACER PC". Source available in FORTRAN 77. "TRACER" runs on Cray, VAX, and many Unix-based systems. "TRACER PC" is for the IBM PC, 640K memory, 20 Mb hard disk, math co-processor, and Targa or Number Nine card. "TRACER PC" includes a modeler.

	Cost: $3000 for source and first year of updates.  Manual for $25.

	Contact: Mark Franklin
		 Ray Tracing Corporation
		 2516 Via Tejon, Suite 316
		 Palos Verdes Estates, CA  90274

United Computer Systems, Inc, "Ray Tracer". Available on Apollo, IBM, and Mac. Evidentally selling well on Mac and IBM: 4x sales than Apollo sales since intro post-SIGGRAPH '87. It turns out that this product is actually made by Ray Tracing Corp.

	Cost: ???, manual available for $25.

	Contact: Alan Brown (at TMAC (sp?)), 213-475-1067
		 United Computer Systems, Inc
		 Graphics Development Group
		 10564 Progress Way
		 Cypress, CA  90630

Wavefront Technologies, Inc, "3-D Dynamic Imaging System". Their system has "production speed ray tracing" as a feature.

	Cost: ???

	Contact: Wavefront Technologies
		 530 East Montecito Street
		 Santa Barbara, CA  93103

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Benchmarks, by Jeff Goldsmith

[This recently appeared in the email newsletter on scientific visualization that Jeff Goldsmith has been editing. If you're interested in subscribing and contributing to the SciVi discussion group, contact him at: jeff@hamlet.caltech.edu . I thought it of interest because of the bounding box intersector statistics. - EAH]

I did an interesting micro-project this winter/spring. We were interested in porting some programs to PCs and/or Workstations, so I compared the performance of a few chunks of graphics code on a bunch of machines. The code was supposed to represent some of the typical cpu and I/O intensive things that graphics programs tend to do.

The benchmarks are:
	Faults:	randomly accesses a huge array (>16 Megabytes)
		(I know--not huge to you Cray users, but it is
		to PCs)  Obviously, tests virtual memory usage.
	Shade: typical shading routine.  Tests floating point
		very strongly.
	Bbox: highly optimized bounding box intersection routine
		for a ray tracer.  (actually, this one has become
		somewhat unoptimized for the testing, but you get
		the idea)  Was intended to test floating point
		performance and if-then-else branching.  Actually,
		tests floating point and caching.
	Clear: sequentially clears a large memory array.  Tests
		compiler, MIPS, and memory usage.
	Sub: calls an empty subroutine repeatedly.  Tests MIPS.
	Fread: formatted reads and writes.  Tests I/O speed, floating
		point performance and MIPS.
	Uread: binary reads and writes.  Tests raw I/O speed.

Machine	faults	shade	bbox	clear	sub	fread	uread
------- ------  -----	----	-----	---	-----	-----
VAX780	12.5	16.9	12.3	11.8	19.3	17.4	23.2
uVAX II 22.2	18.5	15.6	12.9	18.9	24.0	29.1
HP320	*	10	45	4	8	5	6
HP350	4	5	28	3	4	3	4
Sun 3/1	*	9	34	4	6	5	5
Sun 3/2 *	9	48	3	3	2	4
Sun 386 *	9.5	16	2	5	3	1
Mac II	* 	31.3	44.3	*	4.3	13	5.3
PC/AT	* 	70	180	*	39	17	6
PS 2/80 *	9.4	49.7	*	11.1	11.4	7.3
Compaq	~	~	~	~	19.0	13.1	5.5
Iris	*	30	59	4	5	15	3
IrisFPA *	11	13	4	5	6	3

All entries are in seconds to run specified benchmark.
* indicates that operating system not set up to allow
   program to run.
~ indicates benchmark not attempted.

The machines tested:
	VAX780:	Vax 11/780 with FPA and 32 Mbytes memory
	uVAX II:  Microvax II, VMS, 16 Mbytes memory
	HP320: Unix
	HP350: SRX, Unix, 32 Mbytes memory
	Sun 3/1: Sun 3/160, 68881 co-processor
	Sun 3/2: Sun 3/260, 68881 co-processor
	Sun 386: Sun 386i/250, 80386/80387, Unix
	Mac II: MPW, 68881
	PC/AT: Xenix, 80287
	PS 2/80: OS2, 80387 co-processor
	Compaq: Compaq 386, Unix, no coprocessor
	Iris: SGI IRIS 3030 without FPA
	IrisFPA: SGI IRIS 3030 with FPA
	(Iris 3130 performance was identical to 3030.)

What did I learn from all this? One thing is obvious: if a FPA is available for your machine and you can afford it (they are usually cheap) buy it even if you don't do alot of floating point. It affects all sorts of performance characteristics. Another important point: it is not possible to evaluated computer performance as one number. Different computers do different things well.

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Eric Haines / erich@acm.org