[Radiance-general] Mesh smoothing

Sat, 04 Aug 2001 20:59:54 +0200

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Hi Russel,

> Hi all
>
> I have a question about smoothing. If you add the -s switch in gensurf
> you can get
> a smooth shaded surface. Is there any way I can insert this smoothing
> to a surface
> that I have imported from AutoCAD? I do not want to increase the
> polygon count but
> i do want to smooth out the faceted glare on the surface.
>
> Any ideas about this?

surface smooting is done by gensurf with a cal file that manipulates the
surface normal across
a generated polygon. The result is one flat polygon, with a surface
normal that varies across the polygon
(aka Phong shading). However, the true surface has to be known to the
generator to figure out
the intended normal at each point.
With an already tesselated surface that information is lost. One would
have to fit a smooth
(e.g. spline based) new surface to the vertices and recalculate normals
from that, but neither is
the surface what the original surface might have been, nor do I know a
program to do that
(infos, anyone ?).

> On a side note I am also looking at modelling light redirection
> systems (horizantal/vertical
> glazing) and refractive systems. I have looked at some of the designs
> on www.schorsch.com
> and attempted to model them using AutoCAD or a gen program then
> assigning a dielectric
> material. Does any else have experience with creating these and would
> it be possible
> to use a different modifier? I am looking for the most accurate
> calculation.

You may find that classic Radiance doesn't do forward raytracing and
hence won't handle light
redirection with dielectric volume materials. George Mischler, I think,
uses a method developped by
Thomas Schmidt ([email protected]), with does trick classic Radiance to do
this for certain type of
elements. Roland Schregle ([email protected]) is implementing a
photon-map add-on to Radiance
that handles the general case. That's currently in beta and validation
is pending. Thomas work has
been much more crosschecked, but is implicitly not as general.

-Peter

--
 pab-opto, Freiburg, Germany, www.pab-opto.de

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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
&nbsp;
 Hi Russel,
<blockquote TYPE=CITE>Hi all
I have a question about smoothing. If you add the -s switch in gensurf
you can get
 a smooth shaded surface. Is there any way I can insert this smoothing
to a surface
 that I have imported from AutoCAD? I do not want to increase the polygon
count but
 i do want to smooth out the faceted glare on the surface.
Any ideas about this?</blockquote>
surface smooting is done by gensurf with a cal file that manipulates the
surface normal across
 a generated polygon. The result is one flat polygon, with a surface
normal that varies across the polygon
 (aka Phong shading). However, the true surface has to be known to the&nbsp;
generator to figure out
 the intended normal at each point.
 With an already tesselated surface that information is lost. One would
have to fit a smooth
 (e.g. spline based) new surface to the vertices and recalculate normals
from that, but neither is
 the surface what the original surface might have been, nor do I know
a program to do that
 (infos, anyone ?).
<blockquote TYPE=CITE>On a side note I am also looking at modelling light
redirection systems (horizantal/vertical
 glazing) and refractive systems. I have looked at some of the designs
on www.schorsch.com
 and attempted to model them using AutoCAD or a gen program then assigning
a dielectric
 material. Does any else have experience with creating these and would
it be possible
 to use a different modifier? I am looking for the most accurate calculation.</blockquote>
You may find that classic Radiance doesn't do forward raytracing and hence
won't handle light
 redirection with dielectric volume materials. George Mischler, I think,&nbsp;
uses a method developped by
 Thomas Schmidt ([email protected]), with does trick classic Radiance
to do this for certain type of
 elements. Roland Schregle ([email protected]) is implementing a photon-map
add-on to Radiance
 that handles the general case. That's currently in beta and validation
is pending. Thomas work has
 been much more crosschecked, but is implicitly not as general.
-Peter
<pre>--&nbsp;
&nbsp;pab-opto, Freiburg, Germany, www.pab-opto.de</pre>
&nbsp;</html>

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