Le Thu, 05 Jun 2008 19:44:14 +0200, Kenneth <kdw### [at] earthlinknet> a  


> "Bruno Cabasson" <bru### [at] cabassoncom> wrote:
>
>>
>> Concerning the values for the media, I am aware of your advises, thanks
>> anyway for enlighting.
>>
>> The fact is that, with the study on clouds I am currently conducting, I
>> never got acceptable results with only one interval, especially for rays
>> that approach the horizon, and more especially when the sun is at low
>> elevation...
>>
>> In this regard, 3 intervals and 3 samples yield better results that 1
>> interval and 9 or 12 samples.
>
> That's interesting. I usually use the recommended method 3, intervals 1  
> approach
> (basically because it renders faster.)  But your method seems useful and
> logical; I'll have to experiment with it!
>>
>> And, when coding, I generally prefer be explicit rather than use  
>> implicit
>> default values. Depends on cases, and mood ...
>
> I agree! I don't always *trust* that POV's stated default values are  
> correct.
>
> I'm still testing out your nebula code, and will report back with some  
> comments,
> if I can contribute anything useful or helpful. Yes, it's a tasty bone  
> to chew
> on  :-)
>
> Ken W.
>
>

Here is the code for the nebula on th epicture.


#version 3.5;

#include "colors.inc"

global_settings {
   assumed_gamma 1.0
}

// ----------------------------------------

camera {
   location  <0.0, 0.0, -4.0>
   direction 1.5*z
   right     x*image_width/image_height
   look_at   <0.0, 0.0,  0.0>
}


#declare N = 2; // 2 medias

light_source {
   <0, 0, 0>
   color rgb 4/N // light power of 4 is required because high level of  
scattering/absorption
}

// ----------------------------------------
difference
{
     sphere {0, 1}
     sphere {0, 0.01} // The light source must be outside the container,  
otherwise scattering does not work properly (as if extinction were  
inoperative).
     hollow
     pigment {rgbt 1}
     interior
     {
         media
         {
             intervals 10 samples 3 method 3
             scattering {1, rgb 10*<1, 0.7, 0.1>/N}
             absorption 15*(1-OrangeRed)/N
             density
             {
                 spherical scale 0.4
                 scale 10 warp {turbulence 0.6 omega 0.7 octaves 10} scale  
1/10
                 turbulence 1 lambda 1.4 omega 0.8 octaves 10
             }
         }
         media
         {
             intervals 10 samples 3 method 3
             scattering {1, rgb 30*<0.7, 0.5, 1>/N}
             absorption 2*(1-VioletRed)/N
             density
             {
                 spherical scale 0.45
                 scale 10 translate 0.5 warp {turbulence 0.6 omega 0.7  
octaves 10} translate -0.5 scale 1/10
                 turbulence 1 lambda 1.4 omega 0.8 octaves 10
             }
         }
         #end
     }
}

-- 

http://www.opera.com/mail/

Post a reply to this message