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- POV-Ray Tutorial
Content Overview
material, interior, media
- Syntax material
texture + interior
- Window Glass
+ max_trace_level
- Fog, Mist or Haze
Media
- Syntax Media
- Media+Density Maps
Atmospheric Media
with/without density map
- Beames in the Fog
Object Media
Emitting Media
- Light Sword
- Candle Flames
Scattering Media
- Light through Window
- Steam, Smoke, Clouds
Absorbing Media
- Dust Devils
Special Problems with Media
- Scaling of Media
- Overlapping Media
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Scaling Object Media
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Scaling Object Media
If we increase scale of an object media in POV-Ray scene
the media density will not be scaled accordingly!
In consequence more rays will pass through more media than before
and this gives accordingly stronger effects.
I.e. a scattering media scatters more intensively and that's why it looks
darker (c.f.: the second image on this page!).
How to scale Object Media correctly:
To keep the effect constant we need to reduce the
color (i.e. for scattering) by dividing it by the applied scale!
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Object media in scale 1.
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Object media in scale 4.
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Object media in scale 4 with color divided by 4.
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Example: How to scale media
#declare Cloud_Scale = 10;// 1, ... 500
#declare Cloud =
sphere{ <0,0,0>, 1
pigment{rgbt 1}
hollow
interior{ //-----------
media{
emission <1,1,1>/Cloud_Scale
scattering{ 1,<1,1,1>/Cloud_Scale}
density{
spherical
turbulence 0
color_map {
[0 rgb 0.0]//border
[1 rgb 1.0]//center
} // end color_map
} // end of density
} // end of media ---
} // end of interior
scale Cloud_Scale
} //----- end of sphere
//--------------------------------------
object{ Cloud
// don't do any additional scaling here!
translate<0,1,15>
} //--------------------------------------
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And as a macro object:
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Object media with Cloud_Scale 1 at <0,1,1>
Object media with Cloud_Scale 10 at <0,1,15>
Object media with Cloud_Scale 500 at <0,50,600>
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Example: A cloud with media in a macro
#macro Cloud_01( Cloud_Scale )
sphere{ <0,0,0>, 1
pigment{rgbt 1}
hollow
interior{ //-----------
media{
emission <1,1,1>*0.75/Cloud_Scale
scattering{ 1,<1,1,1>*5/Cloud_Scale}
samples 20 // increase = more precise
intervals 1
density{ spherical
scale 0.65
turbulence 1.00
color_map {
[0 rgb 0.0] // border
[1 rgb 1.0] // center
} // end color_map
} // end of density
} // end of media ---
} // end of interior
scale Cloud_Scale
} //----- end of sphere
#end // end of macro ---------------------
object{ Cloud_01( 5 )//Cloud(Cloud_Scale)
// don't do any additional scaling here!
rotate <0,0,0>
translate <0,4,5>
} //--------------------------------------
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Object media Cloud_1, scale 5 at <0,4,5>
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