fish@shape.cis.ohio-state.edu (Keith Fish) (10/20/88)
I'm sure PIXAR is more than willing to send you a spec of Renderman ...
just ask them. Also, there may be something available through the
Siggraph 88 proceedings.
<<< The following is MY understanding of Renderman >>>
Renderman is an attempt by PIXAR to force a defacto standard interface in the
Graphics Rendering/Imaging arena. My understanding is that this interface
is based on tools/routines that they have developed throughout the years for
use on their hardware. Because it was not designed for general/varying
graphics architectures, many companies wonder if it will only work well on
their systems -- hence, making their hardware also the defacto standard.
More importantly, PIXAR already has the software written for this "standard"
so if this becomes a standard, any competitor of PIXAR would have to make the
$$$ investment to write this software -- a good way to limit your competition.
PIXAR made a big push for Renderman at Siggraph 88. Although a few companies
agreed to endorse this package (SUN, of course ... they'd endorse anything to
get their name in lights ;-), many took a more intelligent approach and said
that they would evaluate it. PIXAR basically used a lot of marketing hype
to get support initially and even listed supporters who, when you would
walk up to their booth at Siggraph and ask them, said they did not support it.
Many (most ?) of the companies who looked at Renderman have decided that it
still needs a lot of work before it can be considered as even a base to start
the development of a standard in the rendering/imaging arena. There are
several problems in the area of getting Renderman to mesh with other current
standard graphics environments (eg. phigs, cgi, ...) so that it becomes a
natural extension to the less-interesting/fancy graphics people do today.
Even for the niche market of image-rendering, Renderman does not include
many (any ?) ideas from the companies that have been in this business for
years ... Wavefront, Alias Research, Neo-Visuals, Disney, etc.
Keith Fish
PS. I'm not cutting down PIXAR -- I think that the work they do is
fantastic (literally)! I just don't like marketing ploys to degrade
what should be good technology, and this is what the Renderman-hype
seems to be. I think that the industry can develope a good imaging
interface standard if everyone (animation software companies,
universities, graphics hardware companies, etc.) gets to contribute.upstill@pixar.UUCP (Steve Upstill) (10/25/88)
I'm writing the RenderMan book, so I guess I'm qualified to clear up
a couple of things from this posting:
In article <25225@tut.cis.ohio-state.edu> fish@shape.cis.ohio-state.edu (Keith Fish) writes:
>
>I'm sure PIXAR is more than willing to send you a spec of Renderman ...
>just ask them. Also, there may be something available through the
>Siggraph 88 proceedings.
There's nothing in the SIGGRAPH 88 proceedings about RenderMan. You can
get a copy of the spec by sending $15 (yes, I know it's a pain, but we've
sent out ~1000 specs so far, and it got kind of expensive; this is the
real cost) to
Pixar
3240 Kerner Blvd.
San Rafael, Ca. 94901
>
><<< The following is MY understanding of Renderman >>>
>
>Renderman is an attempt by PIXAR to force a defacto standard interface in the
>Graphics Rendering/Imaging arena. My understanding is that this interface
>is based on tools/routines that they have developed throughout the years for
>use on their hardware. Because it was not designed for general/varying
>graphics architectures, many companies wonder if it will only work well on
>their systems -- hence, making their hardware also the defacto standard.
RenderMan is based on about six years' research at Pixar and Lucasfilm on
how to get quasi-photographic realism into computer graphics. The effort
has encompassed algorithms, software and hardware, and much of what is in
the standard has been proven to work by actually implementing it; so in
some sense the above is a correct statement. However, there is an
implication here that RenderMan is some inhouse methodology that Pixar is
trying to foist off on the rest of the industry. That is definitely
untrue. Pat Hanrahan and Tom Porter spent about six months talking to
other companies in the industry, trying to establish a consensus and
ensure that the standard is technically sound. The best evidence I
have of how much it changed as a result is the amount of work I had
to put into changing my book between Versions 2 and 3 of the spec.
As for the standard being specific to some particular hardware or
software configuration, you just have to look at the standard itself.
From the geometric standpoint, it is a simple protocol for describing
scenes, as generic as can be, and deliberately so. It is essentially
a superset of PHIGS+, with two differences: there is no provision for
changing model descriptions once defined (you have to respecify scenes
from one frame to another), and there are extensions for realism like
the shading language, motion blur and depth-of-field. The hardware-
specificity is a canard, pure and simple. The current (incomplete)
version of our software runs on Sun, Silicon Graphics and '386-based
Compaq machines, as well as on Transputer-based hardware accelerators
in all three.
More specifically, I can tell you that Pat went to a lot of trouble to
make the interface standard independent of even the basic rendering
algorithm. That is, RenderMan is consistent with scanline-based methods
as well as ray tracing; standard shading models as well as radiosity
techniques. That wasn't easy.
>More importantly, PIXAR already has the software written for this "standard"
>so if this becomes a standard, any competitor of PIXAR would have to make the
>$$$ investment to write this software -- a good way to limit your competition.
Sorry. I'm working closely with the software group in trying to
generate pictures and example programs for my book, and I can testify
that the software, while quite far along, is not "already written",
largely because of extensions to the standard that came out of
discussions with other companies. True enough, we probably have a
head start on others, but the standard has been out there for five
months now, and will probably have been around for close to a year
before Pixar has its stuff on the market.
Besides, the standard specifies nine capabilities which are optional for
any particular implementation. No renderer should have any trouble
meeting the RenderMan standard if it supports PHIGS primitives and
performs such quality calculations as anti-aliasing and gamma correction.
>PIXAR made a big push for Renderman at Siggraph 88. Although a few companies
>agreed to endorse this package (SUN, of course ... they'd endorse anything to
>get their name in lights ;-), many took a more intelligent approach and said
>that they would evaluate it. PIXAR basically used a lot of marketing hype
>to get support initially and even listed supporters who, when you would
>walk up to their booth at Siggraph and ask them, said they did not support it.
This comment is borderline offensive to me, partly because it is admittedly
based on speculation and partly because I was around during the process
I mentioned above, and I know what a painful and elaborate job Pat had
to get the proposal into shape to win the support of the companies he did.
There is a difference between endorsement and support. Endorsement means
"we have evaluated this; it is sound and we believe this is the way the
industry should go". Support means "we have hardware and/or software
which implements this standard". You would expect the latter to be a
subset of the former.
Nineteen companies endorsed the RenderMan standard at rollout. The main
holdouts at this point are Silicon Graphics and Wavefront. My personal
suspicion (not to be taken as the views of Pixar) is that Wavefront
perceives RenderMan as a threat to their rendering market because
it supports features which would be difficult or impossible to
implement using their rendering algorithm. And Wavefront software
runs on SGI machines.
>Many (most ?) of the companies who looked at Renderman have decided that it
>still needs a lot of work before it can be considered as even a base to start
>the development of a standard in the rendering/imaging arena.
Who are these "many companies"?? What is this "lot of work"?? We would
love to hear about. There is a RenderMan Advisory Council made up of
industry representatives whose job it is to hear complaints like that.
I don't expect to hear too many of them, however. As I said before,
RenderMan is basically a simple-minded extension of PHIGS (read: EXTENSION.
Meaning "If PHIGS is good enough for you, so should be RenderMan")
adding constructs for supporting realistic graphics. It has gone
through the mill of two major rewrites as a result of consulatations
with "many companies".
>There are
>several problems in the area of getting Renderman to mesh with other current
>standard graphics environments (eg. phigs, cgi, ...) so that it becomes a
>natural extension to the less-interesting/fancy graphics people do today.
What are these problems?? Can you be more specific??
>Even for the niche market of image-rendering, Renderman does not include
>many (any ?) ideas from the companies that have been in this business for
>years ... Wavefront, Alias Research, Neo-Visuals, Disney, etc.
What are these ideas?? Come to think of it, what ideas has Disney
contributed to image rendering?
>Keith Fish
>
>PS. I'm not cutting down PIXAR -- I think that the work they do is
> fantastic (literally)! I just don't like marketing ploys to degrade
> what should be good technology, and this is what the Renderman-hype
> seems to be.
I appreciate your appreciation, but I wish I knew where these
impressions of yours came from.
< I think that the industry can develop a good imaging
> interface standard if everyone (animation software companies,
> universities, graphics hardware companies, etc.) gets to contribute.
Again, I thought that's exactly what we did.
If anyone on the net is interested in more information on RenderMan
without investing $15 in a spec, the current issue of Unix Review
includes an article I wrote discussing the major aspects of the
standard. Also, the November issue of Dr. Dobb's Journal has a
cover story on the shading language, which is RenderMan's doorway
for extensibility.
Steve Upstillallen@granite.dec.com (Allen Akin) (10/28/88)
Pardon, but RenderMan is not a superset of PHIGS or PHIGS+. For example, it includes neither text nor vectors, both of which are integral parts of PHIGS. (My understanding is based on Version 3.0 of the RenderMan specification. Someone please correct me if I'm out-of-date.) Personally, I think this is an advantage. RenderMan covers its application area well, and making it a true superset of PHIGS would only burden it with irrelevant detail. Allen