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"Nekar" <ger### [at] rpmmag co za> wrote:
> "Eric Buddington" <ebu### [at] wesleyan edu> wrote in message
> news:web.44ee43068f5cf101abef64010@news.povray.org...
> > I'm trying to model the Earth's atmosphere (as a sphere) using scattering
> > media.
> > The atmosphere's density follows a e^(height) type function.
> > The available wave types don't seem to include this. I've played with
> > spherical mapping and poly and cubic wave types,but it's unsatisfactory so
> > far.
> >
>
>
> Does this include the troposphere, stratosphere, mesosphere, ozone, etc? Or
> is it just a simple function?
It uses the barometric formula
(http://en.wikipedia.org/wiki/Barometric_formula)
to calculate air density (assuming constant temperature, so it's just
Ae^B(height)), and uses Raleigh (type 4) scattering on that density. I then
scale it to earth size, and squash it to fit the Earth's ellipsoidosity
(That's a word. Really. I bet.)
It seems a little too thin overall, probably because there's a fair amount
of absorption and isotropic scattering in the troposphere that I haven't
added yet.
Clouds would be cool to add, but I think very computationally expensive to
do well (this is video, so I can't afford even 15 minutes per image)
-Eric
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