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From: jk87377@korppi.tut.fi (Kouhia Juhana Krister)
Newsgroups: comp.graphics
Subject: Re: Motion Blur in Ray Tracing
Keywords: Motion Blur Ray Tracing
Message-ID: <1991Feb25.153405.29472@funet.fi>
Date: 25 Feb 91 15:34:05 GMT
References: <471@forum.SUBLINK.ORG>
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Organization: Tampere University of Technology
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In article <471@forum.SUBLINK.ORG> work@forum.SUBLINK.ORG (Forum SuperUser) writes:
>
>BIG PROBLEM: how do you move objects while time-sampling? Should we store
>several complete (huge) databases of objs at different times? Should we
>transform objs every time we want to sample in time (very expensive!)?
>
>What i'm missing?

Probably nothing more than others do...

I have heard that others store all moving objects to the different
place than static objects... guess, they calculate them at the each
time for the each ray. Or they calculate several keyframes and then
interpolate.

I make a motion blur in my system this way...
It's easier to show and draw this; here's a data structure for a
circle moving ball:

(root) - (transform matrix) - (object: table)
       |
       - (procedural matrix) - (object: ball)

A procedural transformation is a program code which is executed once
per ray if there's no speeding up methods used.
For example:
   t = jitter(t);
   Rotz(t*maxangle);

This calculates a transformation matrix on the fly.
You don't have to calculate all datas - just that matrix.

I have designed my program so that it's possible to move objects in
data structures while motion blur.
I mean when you drop a class from your hand it's not anymore in your
hand structure.

Ummm... how you others do motion blur?


Juhana Kouhia
jk87377@tut.fi


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