plasfunc

radiance-general
1

Any advice on using the plasfunc material type? I've searched the Radiance documentation, digests, etc., and the following was the best I could come up with, but it doesn't seem to work. Any advice would be welcome.

I think I should be able to define a material like this:

     void plasfunc myplastic
     2 refl mybrdf.cal
     0
     4 1 1 1 0

and then in a file mybrdf.cal, put an arbitrary definition for the BRDF function refl, something like this:

     refl(x,y,z,area) = (x*Nx + y*Ny + z*Nz)^10;

(This isn't actually the form of BRDF I'm interested in.) Then, I define an object with material myplastic:

     myplastic sphere ball
     0
     4 0 0 .5 .5

When I render this, though (with light sources, other objects, etc. added), the sphere just looks Lambertian. What am I doing wrong?

Thanks,

Richard

2

Hi Richard,

What you did wrong is specified a specularity of 0 in your plasfunc:

    void plasfunc myplastic
    2 refl mybrdf.cal
    0
    4 1 1 1 0

The fourth argument is the fraction of reflected light that is modified by your specified BRDF.

-Greg

···

From: Richard Murray <rfmurray@sas.upenn.edu>
Date: February 6, 2005 2:18:38 PM PST

Any advice on using the plasfunc material type? I've searched the Radiance documentation, digests, etc., and the following was the best I could come up with, but it doesn't seem to work. Any advice would be welcome.

I think I should be able to define a material like this:

    void plasfunc myplastic
    2 refl mybrdf.cal
    0
    4 1 1 1 0

and then in a file mybrdf.cal, put an arbitrary definition for the BRDF function refl, something like this:

    refl(x,y,z,area) = (x*Nx + y*Ny + z*Nz)^10;

(This isn't actually the form of BRDF I'm interested in.) Then, I define an object with material myplastic:

    myplastic sphere ball
    0
    4 0 0 .5 .5

When I render this, though (with light sources, other objects, etc. added), the sphere just looks Lambertian. What am I doing wrong?

Thanks,

Richard