Applying materials & non-orthagonal surfaces

I recently posted a question regarding perforated
metal. The material worked great, but I had to do a
lot of tedious manual labor getting it to work right
on a 3D arch due to the changes in surface normal of
each section of the arch.

So, I've been wondering if there is a better way to
handle adding orientation specific materials to mesh
geometry. (practically all the "advanced" materials
in radiance seem to be orientation specific) So, is
there a tool that will facilitate this process?
Seems like it would need to read a rad file,
calculate the surface normals for the polygons, and
then write out a corresponding material file &
possibly new rad file to go with the material file.
My guess is that's how it would need to work.

Any thoughts?

Thanks! Mark

Hi Mark !

Radiance provides the surface normal of the actual ray hit as Nx, Ny,
Nz. These data are accessible by the caculation engine evaluating the
cal-files, in the same way as the coordinates of the ray hit (Px, Py,
Pz) and some other stuff.

This means that you have to analyze in which way your texture or the
appearance to be produced by it depends on the surface normal, and then
adapt it to the new normal with help of the Nx/Ny/Nz values. (Generally,
this will be a rotation).
By this, the textures can be adjusted to the normals without having to
know the object on which they are applied.

-Carsten

Check out the command obj2rad, which does precisely what you need. It takes geometry from obj files (Wavefront). Those can be produced in FormZ.

Martin

···

-----Original Message-----
  From: dela [mailto:[email protected]]
  Sent: Mon 8/19/2002 1:04 PM
  To: [email protected]
  Cc:
  Subject: [Radiance-general] Applying materials & non-orthagonal surfaces
  
  I recently posted a question regarding perforated
  metal. The material worked great, but I had to do a
  lot of tedious manual labor getting it to work right
  on a 3D arch due to the changes in surface normal of
  each section of the arch.
  
  So, I've been wondering if there is a better way to
  handle adding orientation specific materials to mesh
  geometry. (practically all the "advanced" materials
  in radiance seem to be orientation specific) So, is
  there a tool that will facilitate this process?
  Seems like it would need to read a rad file,
  calculate the surface normals for the polygons, and
  then write out a corresponding material file &
  possibly new rad file to go with the material file.
  My guess is that's how it would need to work.
  
  Any thoughts?
  
  Thanks! Mark
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