Alain <ele### [at] netscapenet> wrote:
> Lonnie nous apporta ses lumieres en ce 2005-06-02 18:42:
>
> > I am about to tear out my hair over the same problem only with refracted
> > light.  It seems that photons and media exclude each other.  My scene is a
> > glass model of a Greek temple, totally transparent material, with ior and
> > dispersion, photons enabled (target) and illiminated by a spotlight.  It is
> > surrounded by a hollow, transparent cylinder filled with scattering media.
> > Interior dispersion works fine, BUT:
> >
> > 1.  When both media and photons are enabled where the media is shadowed by
> > the (transparent) material the media vanishes.  Caustics completely
> > diappear leaving black shadows.
> >
> > 2.  When media is diabled and photons are enabled the caustics work fine and
> > the shadows are correctly rendered in shades of grey.
> >
> > 3.  When photons are diabled and media is enabled the media works fine,
> > showing up even in the shadows.
> >
> > I have spent many hours going over the documentation and I can find nothing
> > about the cause of this.  Here is the code:
> >
> > global_settings {
> >   assumed_gamma 1.0
> >   max_trace_level 15
> >
> >    photons {
> >      count 20000
> >      jitter .4
> >      media 300
> >      max_trace_level 35
> // Add this
>  media 10
> // Add this
> >    }
> > }
> >
> You need to add: media <max_steps> to switch media photons on. The default is media
0 means that NO
> photons are deposited in any media. In that case, direct illumination will light the
media, but
> transmited and reflected light (photons) will ignore your media.
> The mandatory parameter "max_steps" indicate how many photons to deposit in a given
interval.
> Try the test value given. You will probably need to increase it, maybe around 1000
or more to get
> optimum results.
>
> Alain

Thanks Alain, but I tried that and my machine is still not buying.  Indeed,
whenever I enable media it generates NO photons at all.  I tried saving the
photon map and got a message "Could not save photon map.  No photons!"  I
wonder if a have a bad install of 3.6?

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