"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
> > Is it a normal radiosity side effect?
> Is your dirt a layered texture? I think there's a separate max_trace_level
> setting in the radiosity block which would need to be the same as the
> global one. I haven't tried this, though, so I could be wrong...
>
> This would also explain why transparent objects seem to block radiosity
> for some people (there was a post to this effect recently).
>
> > In order to illustrate, here is the cask used in my scene without and with
> > radiosity. I also just noticed that specularity does not show.
> Specular and phong highlights are calculated from light sources alone, I
> think. If you removed the light sources and lit the scene using only
> radiosity then this is to be expected.
>
> I did notice the granularity in your original image, but I wasn't sure if it
> was the desired effect or not!
>
> Bill

Hi Bill!

The texture of the cask is quite complex: inside/outside with several layers
(base wood (when brand new) + 'wheathering' (old aspect) + dirt). The dirty
outside texture is:

// Base wood pigment (brand new cask)
#declare P_CaskBodyBase =  pigment
{
    P_WoodGrain14A
    color_map {M_Wood7A}
    rotate 90*x
    scale <0.2, 1, 0.2>
}


// Base texture for outsides
#declare T_CaskBodyBaseOut = texture
{
    pigment {P_CaskBodyBase}
    normal {granite 1 scale <0.04,1,0.04>*4} // Some relief in the wood
}
texture // Wheathering texture
{
    pigment
    {
        granite
        scale <0.04,1,0.04>*4
        color_map
        {
            [0 color 0.3*ForestGreen transmit 0.1]
            [0.3 color 0.4*DarkWood transmit 0.2]
            [0.7 color 0.7*DarkWood transmit 0.3]
            [1 transmit 0.8]
        }
    }
    finish {specular 0.2 roughness 0.04 } // Somewhat polished by
manipulations
}

// Dirt layer at both ends
#declare T_CaskBodyDirt = texture
{
    pigment
    {
        gradient y
        scale -2*CASK_LOW_THRESHOLD // Cask = differenced elongated spheres,
intersected with 2 planes
        translate -CASK_LOW_THRESHOLD*y
        turbulence 0.1 omega 0.65 octaves 8
        scale 1.1*<0.15,1,0.15>
        color_map
        {
            [0   transmit 0.05]
            [0.2 transmit 0.1]
            [0.5 transmit 0.3]
            [0.8 transmit 0.1]
            [1   transmit 0.05]
        }
    }
}


#declare T_CaskBodyBaseOutDirt =
  texture {T_CaskBodyBaseOut}
  texture {T_CaskBodyDirt}


The dirt layer in the first encountered by the rays (like in real life). I
read the documentation and I did not see a specific max_trace_level in the
radiosity section, but rather adc_bailout, which is closely related. I
tried to tweak this parameter from 1 to 1e-5), but the problem remains.

    Bruno

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