ah, it looks like i need to make other objects hollow too

"Crippso" <nomail@nomail> wrote:
> I tried to include these changes but didn't get the right results.
>
> if i put xscan=0, i have the simple case of photons travelling through the
> absorber and reflected back through it, always in the z direction. Using your
> media approach i dont seem to be able to change the brightness of the reflected
> scene by changing cmt_abs paramter. I also noticed if i set cmt_abs = 0 there is
> no error flagged up because of the divide by zero!
>
> clipka <ano### [at] anonymousorg> wrote:
> > Am 13.07.2012 18:24, schrieb Crippso:
> > >
> > > I tried to use media but cant get it to work properly. Still when my xscan
> > > paramter = 4 the reflection is too bright, it should be much weaker than when
> > > xscan = 3. Here is how i modified the absorber object. The only other change I
> > > made was to the photons global setting where i added "media 100". Am i doing
> > > something wrong?
> >
> > The "media" keyword in the global photons block is irrelevant for your
> > case; it is intended for scattering media.
> >
> >
> > > object{
> >
> > (BTW, while wrapping your "box" in an "object" statement doesn't hurt,
> > it's totally unnecessary; you need "object" only when you have
> > #declare'd an object and want to add it to the scene.)
> >
> > > box
> > > {
> > >     <-extent,-extent,t_st> <extent,extent,t_st+t_abs>
> > >     hollow
> > >     pigment{rgbt 1}
> > >     finish
> > >     {
> > >       reflection{0,1 fresnel}
> > >       conserve_energy
> > >     }
> > >
> > >     interior{ior cmt_ior fade_distance cmt_abs fade_power 1000
> >
> > Remove the "fade_distance" and "fade_power" statements; after all,
> > you're trying to replace them with media.
> >
> > >         media{
> > >          absorption <1,1,1>
> >
> > You may need to increase absorption; note that its parameter is not
> > limited to the range [0..1].
> >
> > Theoretically, you should set:
> >
> >      absorption = <1,1,1> / cmt_abs
> >
> > to get the same results as you'd get with properly computed fade.
> >
> > >          intervals 3
> > >          samples 1,1         }
> >
> > Remove the "intervals" and "samples" statements; the default values
> > should be perfectly fine for uniform media as in your case.
> >
> > >
> > >     }
> > >
> > >     PhotonTarget(no, yes, yes, yes)
> > > }
> > > }

Post a reply to this message