> >I can see the 1 unit == 1 millimeter argument, and I will admit that
> >I like avoiding floating-point math when possible. *However*, if that's
> >the case, the 16-bit format still has the precisions a bit off. With
> >8 bits for the integer part, that means that we only have a range of
> >about a fourth of a meter, which is a bit too little -- we need at
> >least a meter or two, I think. (Plenty of real-world objects are a
> >meter in size, although not too many are more than four meters.) We
> >also don't need a full 8 bits for the fractional part -- that would
> >bring our resolution down to almost micron level, which is *way*
> >smaller than we need.
>
> I have thought for some time that the centimeter was a good compromise.
> for one thing the millimeter is appropriate for one to one mapping of our
> mean visual acuity (sp?) but we will be not be using 1:1 that often. More
> likely our display windows will represent things at about ten percent actual
> size.
Why not follow what the architectural drawing experts and map makers have
done for years, and provide a scale indication? That way, you can specify
for each .wrl file that 1 unit = whatever you want. The default could be 1
meter (if the scale is not specified), and the convention is that the
scale is expressed in whole tens decimal fractions of a meter. This means
that a small, intricate object could be scaled in millimeters as "scale
1:.001", and something huge (like a planet) could have "scale 1:1000", so
it can be expressed in kilometers. Tens decimals means "scale 1:26" and
"scale 1:.37728" would be unnacceptable. This is just a simplification
suggestion, though. Allowing any sort of scale might make it easier to use
files from other systems where the scale is expressed in other units
(feet), instead of meters. The translation process could then provide a
scale tag that would make the object fit correctly in whatever space it's
used in.
---
Andrew C. Esh mailto:[email protected]
Computer Network Technology [email protected] (finger for PGP key)
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