From: dstamp@watserv1.waterloo.edu (Dave Stampe-Psy+Eng)
Newsgroups: sci.virtual-worlds
Subject: Re: TECH: My standard is better than your standard.
Date: 26 Jul 92 14:40:29 GMT
Organization: University of Waterloo
Originator: hlab@milton.u.washington.edu


s047@sand.sics.bu.oz.au (Jeremy Lee) writes:
>
>>Exactly.  Just as we have a (physical) "world scale", we should have
>>a "world time scale".  ("In this world, one unit is one angstrom and
>>one time unit is one nanosecond").
>
>Why a world time scale? If I want a process over here going at 1
>nanaosecond per second, and another over there going at 2 nanoseconds
>per second, does that mean I can't? I think the best way is to throw out
>a "world time scale" and simply ask each of the objects to adopt a time
>scale with *certain other objects*. If they adopt it with every object,
>including you, then I think you will end up with some unreasonable
>behaviour. (eg, you push on the object with a force of 1m/s/s, and it
>takes 1.6 billion years to perform the action)

One of the basic goudelines for a virtual world is going to have to
be "Match the user, dammit!".  Why even bother representing something that
the user can't see, or model tiny effects that would be swamped by friction
or whatever in the real world!  We're NOT planning a worldwide network of
simulation programs, after all.  So as for speed or force, it's OK to
set a minimum force threshold for motion (which is part of the object
description) and allow some quantization.  As for speed, same thing applies. 

>>>Allow the object to decide how to scale itself to the world. How else
>>>am I going to put a representation of myself into the insides of a
>>>virtual single celled animal?
>
>Er, problem. What if I go straight from a world in which I had scaled
>myself up to galaxy size, then I zap over to another world that it at,
>as you say, the size of single cell. I've got to be able to see what I
>am doing before I re-scale myself, and before that I'm going to have all
>sorts of overflow problems due to not fitting in the world. Answer: Use
>128 bit numbers, and "actual size" scaling. Accept no substitutions!

The answer to this has to do with how people percieve themselves.  You
MUST have some constancy in your world, even if it's just the size of
your arm.  Therefore the default should be to match your height in local-
scale units (which will relate directly to the size objects appear on-screen).
You now use the world-scale of the area you stepped into to draw objects in
this area, translating them into local-scale units.  This will let you be
Part of the world description would be a referant to how big people
should appear (you get the general idea).
"very tall" in both worlds, whether that height is 100m or 100um.

This type of scaling has to take place anyway.  Overconcern with things not
representable to the user will not add to the VR experience, but will
result in a slow system.



--------------------------------------------------------------------------
| My life is Hardware,                    |                              | 
| my destiny is Software,                 |         Dave Stampe          |
| my CPU is Wetware...                    |                              | 
| Anybody got a SDB I can borrow?         | dstamp@watserv1.uwaterloo.ca |
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