Nkin wrote:
>
> ... First priority should
> probably be a general strategy which would allow any such system to deal
> efficiently with both shape and color ...
As an extension to defining color, how about material composition &
properties
which may vary discretely or continuously throughout a part?
Does anyone care to suggest potential applications? (Some have already
been
demonstrated using processes like MD*.)
> The STL format was apparently designed to allow for a facet attribute such as
> you describe. This would seem the logical approach for relatively simple
> coloration - in which different models or even different facets of models are
> built in appropriate colors. It would not, however, allow for complex
> variation within facets.
Consider "Texture Mapping" as applied in the Computer Graphics
community. If
the only concern is surface color, it should be possible to associate a
bit-mapped
color defininion to each planar facet.
> ... Accepting the
> STL dominance as a demonstration of its power...
STL is actually quite a powerless representation. It represents parts
using a
collection of oriented facets sitting in space without providing any
topological relationships between them or any way to define higher-order
geometric primitives. If a facet is "lost" during translation, it is
not at
all obvious from examining the file, and the format is exceptionally
redundant
with vertex coordinates repeated numerous times. Its dominance is much
more
likely due to being first to market and the simplicity with which it can
be
generated.
It will serve the RP community well if an improved alternative to STL
can be
developed & accepted before integrating color/properties into part
definitions.
Regards,
Steve
-- ======================================= Stephen J. Rock CII8015 Center for Automation Technologies Rensselaer Polytechnic Institute Troy, NY 12180 USA (518)276-8652 Fax -4897 http://www.rpi.edu/~rocks =======================================For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
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