[Radiance-general] Creating a two material composite material in 2d

[Greg Ward]

Hi Lars,

The "mixpict" primitive should work for this purpose:

void mixpict mat_map
7 white_mat black_mat grey matmap.pic picture.cal pic_u pic_v
0
0

--------
You have to define the two materials "white_mat" and "black_mat" and  
you'll probably want to change the picture coordinate mapping to suit  
your needs, but you get the idea.

-Greg

> From: "Lars O. Grobe" <grobe at gmx.net>
> Date: April 6, 2008 8:27:38 AM PDT
>
> Hi list,
>
> trying to optimize an existing model, I have a rather basic question.
>
> I have a surface, which is composed of two materials. Imagine  
> something like a checkerboard, two materials, just not with squares  
> but irregular forms. I have images of that surface, and of course I  
> could simply map a foto onto a white surface using colorpict and  
> get something close to real.
>
> Still, as I have not only color but two materials involved, I do  
> not like that idea. I want to have different material properties,  
> not only color variation.
>
> So far the problem is solved using two cad geometrys, one for each  
> material. This is extremely inefficent, it produces tons of  
> polygones and problems.
>
> What I need is to take a black white picture, map it onto my  
> surface, and have the black be material a and the white be material  
> b in radiance.
>
> Is there a reasonable way to do that in Radiance?
>
> TIA&CU, Lars.