From: katefans@chinet.chi.il.us (Chris'n'Vickie of Chicago)
Subject: Re: arenderman update!
Organization: Chinet - Public Access UNIX
Date: Wed, 19 Aug 1992 08:42:46 GMT

In article <1992Aug17.204956.10418@westford.ccur.com> mark@calvin..westford.ccur.com (Mark Thompson) writes:
>In article <Bt0nyu.6En@chinet.chi.il.us> katefans@chinet.chi.il.us (Chris'n'Vickie of Chicago) writes:
>>   For the price, many of the programs are acceptable, but none can even 
>>begin to touch the power, quality, flexibility and speed of RenderMan.
>
>Hi Chris, it was good meeting ya at Siggraph...now its time for me to to
>give ya a little grief :-) ........

  OK. Nice to see you too... :-)

>I'll allow the "power, quality, flexibility" portion of that statement to
>stand unchallenged but speed is definitely not one of RenderMan's strengths.
>There is no personal computer implementation of RenderMan that is worth
>using for production without something like the Levco i860 RenderMan
>accelerator.

  Not true. Digital Arts 3.8 is the most fully RenderMan complient renderer
yet, and frankly it runs rings around everything I have found on the Amiga.
I use it on a daily production basis on the following equipment:
   
   A 486-33 clone w/ 8 megs of RAM and a 220 meg hard drive
   a Targa 32 graphics card
   and a Lyon-Lamb controller and a Sony Beta deck.

  Not any sort of super system.     

>Doing things like breaking all primitives up into stochastically
>super-sampled sub-pixel micro polygons is extremely compute intensive
>and nearly approaches the slowness of full ray-tracing. Hence all the
>clamoring for NetRenderMan and workstation based RenderMan servers.

   Not really. In real terms the slowest part of the renderer is still
determining visibility. Breaking the "primitives" into micro-polys is
actually quite quick, although it _is_ hard-disk intensive. An "average"
scene may create a 2 meg "temp" file. It seems to be a special case
of ordinary "clipping."

 From what I've seen, the REYES algorthym is faster than any raytracer.

  Also, remember...these folks clamoring for faster renderers are on
_Macs_! Of course they need faster rendering.

>RenderMan does have many, many advantages, but speed is not one of them.

   It may not appear obvious from reading either the spec, or the "Renderman
Companion" but there are almost infinite areas the clever user can optimize
render speed. For example, "ShadingRate" is number for how often the 
renderer computes the color of a surface. A rapidly changing surface, like
a texture map, needs a fairly high shadingrate, but a dull matte surface
can get by with an amazingly low one. RenderMan allows the user to set
this for every surface name. The shiny, env mapped vase on a dull table
does not force the user to render at a quality wasted on the table.

   "Shaders" are an incredible time saver. The "Chrome" shader can be
run at a shadingrate of 200 (i.e. only determine the color of every
group of ~200 pixels) and get a very nice looking chrome look, without
the cost of an enviorment map.

  On the system mentioned above, I get broadcast quality animation at a very
reasonable 5 minutes a frame. Of course this presupposes that the
operator is not afraid to get his fingers dirty in the RenderMan .RIB
file. This leaves our Mac friends out in the cold.

>%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
>%      `       '        Mark Thompson                 CONCURRENT COMPUTER  %
>% --==* RADIANT *==--   mark@westford.ccur.com        Principal Graphics   %
>%      ' Image `        ...!uunet!masscomp!mark       Hardware Architect   %
>%     Productions       (508)392-2480 (603)424-1829   & General Nuisance   %
>%                                                                          %
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

                                Chris Williams
                                   katefans@chinet.chi.il.us

Newsgroups: comp.sys.amiga.graphics