Subject:
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Re: Smooth surfaces
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Newsgroups:
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lugnet.cad.ray
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Date:
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Fri, 21 Sep 2001 12:58:15 GMT
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Viewed:
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2636 times
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In lugnet.cad.ray, Lars C. Hassing writes:
> Lothar Teichert wrote...
> > I think the following is of interest in this newsgroup:
> > L3P generates "meshes" of parts from Ldraw, that are not in LGEO and not
> > covered by other special handling.
> > Meshes consist of triangles and there are creases, if triangles from
> > different planes collide.
> > I remembered the notion of "creaseangle" in VRML and adopted it to
> > replace the triangles of L3P by "smooth_triangles" (see POVRAY-Help for
> > explanation, some computing of normal directions is necessary).
> > Resulting surfaces look more smooth though you may not expect too much.
> > See some examples at http://members.aol.com/elferwette/LDraw/index.htm.
> > Is it worth to ask Lars Hassing for integration in L3P, e.g. controlled by
> > commandline parameters?
>
> Hi and welcome Lothar,
> Yes, I think it is worth to ask him :-)
>
> What a brilliant idea. I had completely forgotten about the smooth_triangle.
> The one example you provide looks very nice.
>
> Do you have more examples?
>
> Do you have any examples where it doesn't work well ?
> (It "removes" the white grille on 3010p20w.dat Brick 1 x 4 with Town Car White Grille,
> and the mouth of 3626bp01.dat Minifig Head with Standard Grin Pattern)
>
> Which angle is best for a default ?
> (I found that 155 works well.
> If smaller, some slope bricks get undesirably smoothed.
> I think the angle should be just below 157.5 degrees,
> which is the angle between surfaces of a cylinder made of 16 surfaces)
Another idea is to choose different angles depending on how long the
edges are next to that angle. For longer edges, a smaller bend is
more likely to be a real crease. I used to use this sort of heuristic
in edge detection image processing software for scanned CAD drawings.
Don
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Message is in Reply To:
 | | Re: Smooth surfaces
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| Lothar Teichert wrote... (...) Hi and welcome Lothar, Yes, I think it is worth to ask him :-) What a brilliant idea. I had completely forgotten about the smooth_triangle. The one example you provide looks very nice. Do you have more examples? Do you (...) (25 years ago, 20-Sep-01, to lugnet.cad.ray)
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