[Radiance-general] Textures: perturbations in x,y,z normals

[Gregory J. Ward]

Hi Adriana,

If you are hoping to model diffraction effects -- where geometric  
optics break down and wave optics take over -- you will be  
disappointed to learn that Radiance does not handle this case.  Few  
ray-tracing systems do.  Diffraction becomes important when the scale  
of surface variations (texture or thin films) is on the order of the  
wavelength of light, less than a micron or so.  For this, you need a  
tool such as Code V from ORA:

	http://www.opticalres.com/news/cv96.html

I believe they have student pricing for their tools.

-Greg

> From: alira at gsd.harvard.edu
> Date: April 24, 2006 4:29:07 PM MST
>
> Hi Greg,
>
> In effect, what I get is the resemblance of a shpere the larger the
> object. For this reason, I feel that I'm using "texfunc" in an  
> improper
> way for what I need. My objective is to modify the x, y and/or z  
> normals
> of a surface in order to analize how much R, G and/or B is being
> absorbed/reflected. I know that depending on the texture of a  
> surface, for
> example, shortwavelenghs of the spectrum are more reflected than  
> the short
> waves of the spectrum. What I need is to create a "bumpy" surface  
> in order
> to see how much blue is reflected depending on the scale of this
> "bumpiness" ( from very small scale-microscale, if possible, to
> macroscale) and by having control of the perturbation of the x, y  
> and z
> normals. Is there a logic way in how to do this?
>
> Adriana