Re: VRML, STL and other animals

From: Michael New (
Date: Thu Jan 11 1996 - 01:19:48 EET

Tony writes:
> The surface normal at a vertex can be used to approximate a curved
> surface using a planar facet. This is used for Phong and Gourad shading
> to create a smooth-looking shaded model using a model with a relatively
> small number of facets. For example, if you are defining a sphere, you
> obviously can only approximate the surface with facets. What you would
> really like to do for shading such a sphere is instead of using the same
> color for an entire facet which will produce a visibly faceted surface,
> is to gradually change the color of a facet over its surface so that the
> color at the edges of the facet match the color of its neighbors, thereby
> producing a smooth-looking surface. The way this is done is to use a
> normal at each corner that represents the direction that the corner
> should actually be facing. This is difficult to explain, but there are
> some pictures and descriptions at the following web page:

I understand what you're saying, but why do you want to be able to do this
with an SLA file?

> There are probably others, but this is the first one that I found. This
> same smoothing process that is used for shading could be used to smooth
> RP parts if that information is included in the file.

This would be worthwhile, I suppose. Has anyone explored this idea?
Actually it seems promising.

Mike New

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