[Radiance-general] Specifying surface properties from BTDF data

[Gregory J. Ward]

Hi Frank,

The transdata function will allow you to specify an arbitrary BRDF on  
a surface, but it won't necessarily do what you want unless you use  
the photon-mapping add-on by Roland Schregle.  I plan to work on a  
module that will create "window sources" similar to mkillum given  
measured BTDF data, but this won't be ready for some months.

I realize this isn't much help, but I'm afraid the options are  
currently somewhat limited.

-Greg

> From: "FrankBob Holly" <istvan43 at hotmail.com>
> Date: April 20, 2007 11:14:38 AM PDT
>
> I'm pretty new to Radiance, so please bear with me ;)
>
> I have a commercial forward ray tracing program that I use to model  
> complex window glazings. I can output the transmitted flux vs  
> outgoing direction for light incident at different angles.
>
> How would I create a surface in Radiance which would behave in the  
> same way as observed using the forward ray tracer. BRTDfunc? Can I  
> specify arbitrary output distributions for a comprehensive sampling  
> of all incoming directions? Is there a "BRTDdata" surface type?
>
> Any ideas? Other things I should be aware of?
>
> Thanks
>
> Frank