Re: Color RP Systems

Date: Wed Dec 06 1995 - 20:08:37 EET

> Mike Brindley wrote:
> Peter Gien wrote:
> >
> > But coming back to the old STL format, how are we going to shoe-horn color
> > information into it? As for textures, perhaps Mr. Brock Rooney might wish to
> > enlighten us on how many triangles would be needed to represent realistic
> > surfaces, such as grass and hair?
> >
> If we cram color information into an STL file, it will no longer be
> an STL file! Of course, if the STL file format had been tagged, it
> would be quite easy to add additional information (of any type) to
> the file/model. And any application which does not know about or
> care about some of the data could easily skip it.

Well, if you look at the Binary STL file, there is that 2 byte pad at
the end of each facet. I have on occasion used that for "special use"
type stuff when playing with STL info. The readers don't care, so it
is backward compatable. Just a thought...

> For RP purposes, we do not want different colors for different triangles;
> we want different colors/materials for different VOLUMES. The triangles
> are just a way of defining the desired volume. Therefore, it seems
> that you would want to associate different colors/materials with different
> tessaleted volumes. It would be best to keep both the model and
> any auxillary information (including color/material) together (i.e.,
> in the same file). It would also be desireable to keep the various
> pieces together (in the same file). Of course, a tagged data format
> would handle all of this in its sleep, so to speak.

This is the downfall of what I said above. Mike is absolutely right.
Tagging facet colors will work fine to build a model of Mount Fuji,
but to build the Tumor-in-the-Skull you need to color volumes corectly.
This poses some interesting file and data manipluation questions. If
I can lay down any of 4 colors, which one(s) do I use in an area?? I
figure if we throw the problem at Mr. (Dr.?) Rock, Mr. Rooney and Mr.
Brindley, 3 good answers should fall out.


Chuck Kirschman
"I don't NEED to compromise my principles, because they don't have the
 slightest bearing on what happens to me anyway." - Calvin

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