I understand what media_interaction does. The problem is, even when light is
not scattered by media, the media still casts shadows!

IMO, the correct behaviour would be the following:
1) interaction on & attenuation on - light is scattered and attenuated (the
media casts shadows, unto itself and other objects/medias);
2) interaction off & attenuation on - light is not scattered but the media
still casts shadows from this light source;
3) interaction on & attenuation off - light is scattered, but _not_
attenuated, i.e. the media casts _no shadows_ from this light source, not
unto itself, not anywhere else;
4) interaction off & attenuation off - the media is not affected by this
light source in any way.

Because of a pseudo-bug in transmit, conditions 3) and 4) behave in the
described way when the container objects uses transmitted transparency
(regardless of media_attenuation setting). But with filtered transparency,
media casts shadows under all of these conditions.
All in all, I cannot see any difference in the rendered image, whether
media_attenuation is on or off.

Margus

Lars W. wrote in message <3711dff8.0@news.povray.org>...
>The Point for the media_interaction parameter is that
>you can exclude some of your light sources from the media computing
>process, let's say you have a scene with one primary light ( The Sun )
>and you have an media object ( some clouds ) and then you have many other
>lights, with fade_power and distance assigned, which never reach the
clouds,
>then you can turn the media_interaction for those lightsources off to get
>faster rendering times.
>
>i think thats the only reason this feature exists.
>
>by the way does anybody know how to turn off recieving shadows
>with scattering media ?
>
>greetings Lars
>

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