High!

This weekend, I added a media atmosphere around my planet Ghurghusht... 
after some tinkering, I found out that generally, it works using 
scattering media only. But I wonder why the sky has such a strange color 
close to the horizon... and as I took a shot at the zenith, it turned 
out darker and duller than expected!

Here is the definition of the atmosphere:

#declare Atmosphere =
sphere
{
   0, 5190
   hollow
   material
   {
     texture
     {
       pigment
       {
         color rgbt 1
       }
     }
     interior
     {
       media
       {
         scattering { 1, <0.8, 0.8, 1>/80 }
         density
         {
           spherical
           density_map
           {
             [0     rgb <0.25, 0.5, 1>]
             [0.005 rgb <0.25, 0.5, 1>]
             [0.011 rgb <0.9, 1, 1>]
             [1    rgb <0.9, 1, 1>]
           }
         }
       }
     }
   }
}

See you in Khyberspace!

Yadgar

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Attachments:
Download '2010-03-28 ghurghusht, centlivres lacus from 1.7 metres, looking north, take1.jpg' (19 KB) Download '2010-03-28 ghurghusht, sky above centlivres lacus from 1.7 metres, take 1.jpg' (4 KB)

Preview of image '2010-03-28 ghurghusht, centlivres lacus from 1.7 metres, looking north, take1.jpg'

Preview of image '2010-03-28 ghurghusht, sky above centlivres lacus from 1.7 metres, take 1.jpg'

> High!
>
> This weekend, I added a media atmosphere around my planet Ghurghusht...
> after some tinkering, I found out that generally, it works using
> scattering media only. But I wonder why the sky has such a strange color
> close to the horizon... and as I took a shot at the zenith, it turned
> out darker and duller than expected!
>
> Here is the definition of the atmosphere:
>
>
> See you in Khyberspace!
>
> Yadgar

As you go deeper in the media, there is less blue. The blue gets 
shadowed out.

When you look up, the media depth becomes small and insufisent to be seen.
Try scattering{2...} or {3...}


Alain

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> This weekend, I added a media atmosphere around my planet Ghurghusht...
> after some tinkering, I found out that generally, it works using
> scattering media only. But I wonder why the sky has such a strange color
> close to the horizon... and as I took a shot at the zenith, it turned
> out darker and duller than expected!

The horizon looks pretty fitting to me, kind of like dusty air.

As for the dark zenith, you'll have to increase the density of the upper 
atmospheric layers.

While at the zenith all atmospheric layers have equal influence on the 
resulting color, near the horizon the lower atmospheric layers greatly 
dominate, because the light travels through them at a (comparatively) 
much shallower angle than through the upper layers.

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High!

clipka wrote:

> The horizon looks pretty fitting to me, kind of like dusty air.

Do you think so?

> As for the dark zenith, you'll have to increase the density of the upper 
> atmospheric layers.

How could I do that without increasing the radius of the atmo-sphere? 
The whole thing should look believable also from orbit...

See you in Khyberspace!

Yadgar

Now playing: Friends Of Mine (Duran Duran)

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=?ISO-8859-1?Q?J=F6rg_=27Yadgar=27_Bleimann?= <yaz### [at] gmxde> wrote:
> High!
>
> This weekend, I added a media atmosphere around my planet Ghurghusht...
> after some tinkering, I found out that generally, it works using
> scattering media only. But I wonder why the sky has such a strange color
> close to the horizon... and as I took a shot at the zenith, it turned
> out darker and duller than expected!
>
> Here is the definition of the atmosphere:


If you want really tight control over the way the colors appear, you can alter
the ratio between scattering and absorption by reducing the extinction and
including an absorption component to compensate.  Something like:

media{
  #local Thickness = 1/80;
    absorption color rgb <1.0, 0.8, 0.8> * Thickness
    scattering {
     1, color rgb <1, 1, 1> * Thickness
     extinction 0.5
    }
}


This scatters all colors equally, but absorbs more red.  You can try several
variations until you find one that produces the colors you desire.  I would also
increase the amount of samples to higher than the default.

    HTH
  -Reactor

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Reactor wrote:
> media{
>   #local Thickness = 1/80;
>     absorption color rgb <1.0, 0.8, 0.8> * Thickness
>     scattering {
>      1, color rgb <1, 1, 1> * Thickness
>      extinction 0.5
>     }
> }
> 
> 
> This scatters all colors equally, but absorbs more red.  You can try several
> variations until you find one that produces the colors you desire.  I would also
> increase the amount of samples to higher than the default.

Meanwhile, I found a quite believable ground view sky (scattering type 
1) - at least as long  as the sun is not close to the horizon. But when
I try a view from space using the same settings, the atmosphere turns 
out to look much too dense (in fact, scattering type 2 or 3 does it 
better, but then the sky in the ground views is too dark), see attached 
image...

See you in Khyberspace!

Yadgar

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Attachments:
Download '2010-03-29 ghurghusht, substellar point from 1.7 metres, looking south, take1.jpg' (10 KB) Download '2010-03-29 ghurghusht, sky above substellar point from 1.7 metres, take 1.jpg' (5 KB) Download '2010-03-29 ghurghusht with qais, take 1.jpg' (59 KB)

Preview of image '2010-03-29 ghurghusht, substellar point from 1.7 metres, looking south, take1.jpg'

Preview of image '2010-03-29 ghurghusht, sky above substellar point from 1.7 metres, take 1.jpg'

Preview of image '2010-03-29 ghurghusht with qais, take 1.jpg'