Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!uoregon!tillamook!markv
From: markv@tillamook.uucp (Mark VandeWettering)
Newsgroups: comp.graphics
Subject: Re: Ray Trace for IBM
Message-ID: <3793@uoregon.uoregon.edu>
Date: 13 Feb 89 19:25:03 GMT
References: <986@novavax.UUCP> <2897@m2-net.UUCP>
Sender: news@uoregon.uoregon.edu
Reply-To: markv@tillamook.UUCP (Mark VandeWettering)
Organization: University of Oregon CIS Dept.
Lines: 26

In article <2897@m2-net.UUCP> sa@m-net.UUCP (Scott A. Almburg) writes:

>Doesn;t  ray  tracing take up huge amounts of cpu time?  Does anyone
>have examples  of  cpu time/ frame on various machines?

Well, last time I checked my raytracer on a 20Mghz 68020 and 68881,
I managed to trace a scene with 8192 reflective spheres in ~2.5 hrs.
Unfortunately for the PC, segmented memory confines you to small numbers of 
objects, or use large model (or huge, or superhuge, or whatever) which
slows all pointer dereferencing.  I've never really played to much with 
PCs, so I don't have any hard figures for them.

People in general overestimate the amount of CPU time that raytracing takes.
Improvements in hierarchy methods have made it quite feasible to use
raytracing.  Certainly the next generation of workstations will help.
Combined with the generality and (relative) simplicity of the method, 
raytracing is in many ways a superior algorithm to many scanline algorithms.

>I would think  several hundred hours per frame on an ibm might not
>be too far off...

People who have been working on my raytracer have reported times on the order 
of a day for moderately complex images rendered on the PC.  It's all in the
tuning and optimization....

Mark VandeWettering