"Bruno Cabasson" <bru### [at] cabassoncom> wrote:
> "And" <49341109@ntnu.edu.tw> wrote:
> > "Bruno Cabasson" <bru### [at] cabassoncom> wrote:
> > > Hi there !
> > >
> > > Long time so see... I can't say I'm back, but after a while in hibernation
> > > concerning POV-Ray, I recently revived my clouds. This render took 1h 45 mn on a
> > > Xeon quad E5-1620 V2 @ 3.7GHz, with latest version 3.8 and with "+a0.05  +am3
> > > +ac0.99 +r4".
> > >
> > > Regards
> >
> > I was finding you. Your cloud is the best one here.
>
> Thanks!
>
> However I am far from being satisfied. I encounter issues with radiosity and
> media (camera inside or outside the container, you can play with LAYERx_H
> parameters, lower or higher than camera height). In the absolute, POV-Ray lacks
> specialized density functions that fit into a spherical shell.
>
> Besides, real atmosphere is a very complex thing, not easy to model, and real
> clouds are also quite complex and there are many kinds of them, each one having
> a specific behaviour with light.
>

Do you know I was developing a sky render program? I posted here
http://news.povray.org/povray.binaries.utilities/thread/%3Cweb.584e880d61e083edb1eb18a80%40news.povray.org%3E/

I have used java instead povray for this project for 3 years. The most important
thing which I found pov-ray lacks is the multiple scattering media.
It only scatters light one time, for a thin media(density*length is small I
called thin) that's ok. But for a dense media like cloud it is not enough.
For example, the sky (atmosphere) itself is belong thin media(but in the gray
area because it extend thousands kilometers).



> I also cannot figure out whether and how spectral rendering could help.

It makes secondary difference. My render use spectral rendering:
http://news.povray.org/povray.binaries.utilities/message/%3Cweb.5c791c9887bb2a51e50399380%40news.povray.org%3E/#%3Cweb.
5c791c9887bb2a51e50399380%40news.povray.org%3E

And Terragen use rgb rendering:
https://planetside.co.uk/whats-new-in-terragen-4/#tg4-ozone-simulation

The rgb rendering is more vivid but not so realistic in color and the spectral
rendering is more realistic. But the difference is secondary.
You can compare them.



>
> B.
>
> PS: I could get the POV-Ray code into VS Community and have my own build! For my
> first steps inside, I implemented the f_shell_exp() function I was talking about
> earlier (==> one more entry in functions.inc).


I'm curious about your clouds with two points. One is the shape because your
cloud is much better than my attempt in the shape, the other is how you can use
POV-Ray rendering clouds so white. If I use a single scattering media like
POV-Ray rendering cloud, it will too dark. I leave a message last year.
http://news.povray.org/povray.binaries.images/thread/%3Cweb.5b55d315158ef036e897ce530%40news.povray.org%3E/

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