Hi friends!

Still working on atmospheres and cloudscapes. Here is something a bit
satisfactory and I wanted to submit. Only sky, no terrain. No haze near the
horizon like it should be, and only one layer (further development ...).

Criticisms very welcome.

    Bruno

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Attachments:
Download 'atmo_2.png' (164 KB)

Preview of image 'atmo_2.png'

"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
> Hi friends!
>
> Still working on atmospheres and cloudscapes. Here is something a bit
> satisfactory and I wanted to submit. Only sky, no terrain. No haze near the
> horizon like it should be, and only one layer (further development ...).
>
> Criticisms very welcome.
>
>     Bruno

Only one criticism... not big enough to swipe and use for wallpaper ;-)

Seriously, I love it.  Just a LITTLE to good to be true, the image hovers
pleasingly on the thin border between realism and fantasy.  Further
development?... IMHO, it would look great with a slightly unearthly terrain
and a lone explorer silhouetted in the distance.

Regards,
Mike C.

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Mm, pretty. :-)

-- 
William Tracy
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|w|t|r|a|c|y|@|c|a|l|p|o|l|y|.|e|d|u|
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You know you've been raytracing too long when people around you are 
astounded by the computer-animated tails they put on babies in The 
X-Files. You complain that it looks fake because they didn't bother to 
put in the tails' shadows.
Jeff Lee

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beautifull colors, but the clouds look a bit flat to me
"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote in message 
news:web.4667e9f8b05b8bfbe8ba46670@news.povray.org...
> Hi friends!
>
> Still working on atmospheres and cloudscapes. Here is something a bit
> satisfactory and I wanted to submit. Only sky, no terrain. No haze near 
> the
> horizon like it should be, and only one layer (further development ...).
>
> Criticisms very welcome.
>
>    Bruno
>

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"Mike the Elder" <zer### [at] wyanorg> wrote:
> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
> > Hi friends!
> >
> > Still working on atmospheres and cloudscapes. Here is something a bit
> > satisfactory and I wanted to submit. Only sky, no terrain. No haze near the
> > horizon like it should be, and only one layer (further development ...).
> >
> > Criticisms very welcome.
> >
> >     Bruno
>
> Only one criticism... not big enough to swipe and use for wallpaper ;-)
>
> Seriously, I love it.  Just a LITTLE to good to be true, the image hovers
> pleasingly on the thin border between realism and fantasy.  Further
> development?... IMHO, it would look great with a slightly unearthly terrain
> and a lone explorer silhouetted in the distance.
>
> Regards,
> Mike C.


Next one will be 1024*768, promess...

I am trying to find general pinciples for good skies, especially sunsets, by
imitating phyical phenomena instead of faking them (eg use of a earth-sized
spherical container with Rayleigh scattering of blue color with 'real'
density of the air particles, instead of a sky_sphere with a color_map). As
the renders are quite long, I can only do 1 or 2 tries a day ...

When I feel I am on something interesting, I'll combine with terrains and
try to automate the creation process. It is still embryonic, and a lot of
work is ahead.


   Bruno

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"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote in message 
news:web.4668773643579e8de5a817210@news.povray.org...
> I am trying to find general pinciples for good skies, especially sunsets, 
> by
> imitating phyical phenomena instead of faking them (eg use of a 
> earth-sized
> spherical container with Rayleigh scattering of blue color with 'real'
> density of the air particles, instead of a sky_sphere with a color_map). 
> As
> the renders are quite long, I can only do 1 or 2 tries a day ...

hmmmm ..... interesting. I'm working on an approach that involves the 
sky_sphere as that outer most layer (gradient blues) and concentric spheres 
with largely transparent portions. I've declared pigments (PinkClouds, 
DarkClouds, DarkerClouds) based on wrinkles pattern then textured the 
spheres using bozo and texture_map. I'm having moderate success varying the 
finish parameters from sphere to sphere to give it depth. I agree simple 
sky_sphere with a color_map falls short of the look I'm trying to achieve. 
I've avoided media solutions up until now because of the render time but 
your approach has me reconsidering that, as I've not yet achieved the look I 
want .... thanks for the nudge!

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"Jim Holsenback" <jho### [at] hotmailcom> wrote:
> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote in message
> news:web.4668773643579e8de5a817210@news.povray.org...
> > I am trying to find general pinciples for good skies, especially sunsets,
> > by
> > imitating phyical phenomena instead of faking them (eg use of a
> > earth-sized
> > spherical container with Rayleigh scattering of blue color with 'real'
> > density of the air particles, instead of a sky_sphere with a color_map).
> > As
> > the renders are quite long, I can only do 1 or 2 tries a day ...
>
> hmmmm ..... interesting. I'm working on an approach that involves the
> sky_sphere as that outer most layer (gradient blues) and concentric spheres
> with largely transparent portions. I've declared pigments (PinkClouds,
> DarkClouds, DarkerClouds) based on wrinkles pattern then textured the
> spheres using bozo and texture_map. I'm having moderate success varying the
> finish parameters from sphere to sphere to give it depth. I agree simple
> sky_sphere with a color_map falls short of the look I'm trying to achieve.
> I've avoided media solutions up until now because of the render time but
> your approach has me reconsidering that, as I've not yet achieved the look I
> want .... thanks for the nudge!

I think the use of media can be OK for some reasons:

  -) Generally, the sky is not the main subject of outdoor scenes (but
contributes a lot to the visual effect)
  -) If so, the artist might do an effort for patience to get what he wants,
if it is good quality and more or less automatic (through settings)
  -) I imagine that the skyscape can be rendered with a semi-spherical
camera in order to produce a sky-dome image, then map it onto a sphere, and
then find a trick to fake the lighting. I wonder anyway whether it can
easily be made suitable for radiosity and for the clouds to cast shadows on
the terrain.

My work so far tells me that when the sun is not too near from the horizon,
I don't need that many samples to get a near-photo result, and the render
time is acceptable. BUT for low elevations (I focus on sunsets), I
encounter sampling problems and perhaps numerical artifacts, probably due
to the small angles involved and the length of the path through the
container, and I need to increase the samples and/or intervals. However,
the colors I get are OK and quite realistic: the blue of the sky is
obtained by Rayleigh scattering and a density function for the atmosphere,
and the colors redden while the sun approaches the horizon. My main concern
by now is to get good cloud sampling at low/negative elevations.

Maybe your previous works with media can help and give information. I still
feel that I am not that far from a complete solution for skyscapes, but I
bang my head on the walls for low elevations until I find the trick (if
any): happy me if I find it, shame on me otherwise ...


   Bruno

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I forgot to say that I cannot figure out how an entire skyscape could be
obtained with DF3 files. But I know so little and can't compete with most
of you here ...

    Bruno

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"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote in message 
news:web.4669641f43579e8de8ba46670@news.povray.org...
> the colors I get are OK and quite realistic: the blue of the sky is
> obtained by Rayleigh scattering and a density function for the atmosphere,

i'm curious .... what color blue are you using? not pure blue? i'm playing 
with a tweeked skyblue from kolors.inc

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"Jim Holsenback" <jho### [at] hotmailcom> wrote:
> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote in message
> news:web.4669641f43579e8de8ba46670@news.povray.org...
> > the colors I get are OK and quite realistic: the blue of the sky is
> > obtained by Rayleigh scattering and a density function for the atmosphere,
>
> i'm curious .... what color blue are you using? not pure blue? i'm playing
> with a tweeked skyblue from kolors.inc

Depending on the effect I want it may be from <0.1, 0.2, 1> to <0.4, 0.6, 1>
or so (normalized afterwards). I first tweak the atmosphere, more sensitive
for low elevations where the blue component is more scattered by the
thickness of the media, leading to reddening sky), then I tweak the clouds
density function and the light power.

Here is another try with 2 layers. But I am absolutely not satisfied:
turbulence and thresholds not very good.

    Bruno

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Attachments:
Download 'sunset_4.png' (215 KB)

Preview of image 'sunset_4.png'