"Tim Attwood" <tim### [at] anti-spamcomcastnet> wrote:
> From a scientific point of view POV doesn't even attempt
> to simulate actual RL scattering. Instead rays pass from
> the camera through a media without bending or scattering.

That's not quite true.

What you describe is how POV-Ray goes about emissive and absorbing media. Also
note that there's nothing complicated about simulating such media, as the only
thing to take into account is the distance travelled, as well as the absorption
or emission coefficient, respectively (though the coefficients can vary over
space; numerical integration is used to account for this).

With scattering media, POV-Ray *does* make some attempt to simulate RL
scattering. It should be noted, however, that only first-order scattering is
computed, making it a good approximation only for media with low scattering
coefficients.

The phase function of a medium is approximated by the different scattering
types; I am not an expert on optics, but I guess the functions provide a fair
amount of good approximations for RL phase functions, unless you want to
simulate some sophisticated optical experiment.

Theoretically, it should be no big deal to extend POV-Ray's scattering types
with a user-specified phase function, but there's currently no interface in the
SDL for that.

Post a reply to this message