Simple scene file posted to povray.text.scene-files.  Simple image too.  I
know this has been done before, just trying to keep up on my media skills.

Bob H.
--
http://webpages.charter.net/omniverse/omniverse.htm

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Download 'sun_behind_clouds.jpg' (10 KB)

Preview of image 'sun_behind_clouds.jpg'

Hi Bob,
Looks far from simple! I would say it tends to be more realistic (than
simple).
Never saw such a good cloud-sun-interaction before!
Maybe the cloud is too spherical, but that can happen by accident.
And it looks like an artificial cloud in a realistic
sun-sky-environment - it is too poluted to be just water - a little
redish.

cukk

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"Bob H." wrote:
> 
> Simple scene file posted to povray.text.scene-files.  Simple image too.  I
> know this has been done before, just trying to keep up on my media skills.
> 

The changes in brightness inside the cloud could be smoother, also the
coloring seems strange, the bright parts of the rim are yellow-green while
the dark middle of the cloud is red.

And of course the sky directly around the sun should be brighter, how
about a glow?

Apart from those minor things it looks really nice.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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I used the "late afternoon" or "early morning" light color, I forget now.
The atmospheric media really changed things far as cloud color went but I
just adjusted it all again and uploaded.  Figured anybody would change it
all anyhow.

"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3B570226.C0E23118@gmx.de...
>
> The changes in brightness inside the cloud could be smoother, also the
> coloring seems strange, the bright parts of the rim are yellow-green while
> the dark middle of the cloud is red.

I think increasing samples might help it, used a pretty low number (about
the layering look).  Then again, using less samples actually removes the
stepping some too.  I wanted it to look turbulent though, and not smoothed
out.  Some real stormy clouds before the rain I've often seen were my
inspiration.

> And of course the sky directly around the sun should be brighter, how
> about a glow?

Change the atmosphere media to use scattering type 2 instead and it will
"glow"  :-)  which also means you'd need to compensate and lower the
scattering.
Type 5 is nice I think:  scattering {5,<.03,.025,.02> eccentricity .33
extinction .9}

> Apart from those minor things it looks really nice.

Btw, the eccentricity value will change the cloud itself considerably.
Lower is less silver-lined, higher is moreso.
Never minor stuff when it's endlessly adjustable I guess.  Thanks for
pointing those things out.

Bob H.

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"KalleK" <kal### [at] gmxde> wrote in message news:3b56f83e$1@news.povray.org...
> Hi Bob,
> Looks far from simple! I would say it tends to be more realistic (than
> simple).
> Never saw such a good cloud-sun-interaction before!

Sure you have, outside in the fresh air  ;-)  Only joking.

> Maybe the cloud is too spherical, but that can happen by accident.
> And it looks like an artificial cloud in a realistic
> sun-sky-environment - it is too poluted to be just water - a little
> redish.

All that is the simple part.  Just something to show the effect.  Wasn't the
plain white (rgb 1) or "noon" sunlight color for this render, otherwise it
would have been more purplish-gray.
As we all know, clouds are varied beyond the usual meteorology descriptions
seen in drawings showing their types.  Probably why it can be so
fascinating, in both ray trace and real life.
I thought I was onto something, far as making a smoke cloud though, for the
redder sunlight ones.  I wasn't getting the dayglo fluorescent red-orange I
wanted and it looks more like forest fire smoke.

Bob H.

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