Margus Ramst wrote:
> 
> I believe what you're seeing is a known problem with functions that use noise or
> dnoise (for example bozo, bumps and granite patterns, and turbulence).
> Specifically, the problem manifests itself at large negative distances from the
> origin (e.g. -10000 for bozo, -10000/128 for granite). A workaround is to
> translate your pattern in the positive direction.
> There is also an unofficial version that (reputedly) fixes the problem:
> http://www.enst.fr/~jberger/mpov/mpov.html


G'day Margus,

Thanx for the info.  Evidently there's no NT version yet of the
"MegaPOV patch", and I don't feel like grabbing the DOS version,
so for now I'll just work around it.  I haven't yet tried your
translation suggestion.  After I posted I cruised through all
of POV-Ray's demo includes, and decided I could use GRANITE instead
of scaled BUMPs.  By default, GRANITE's patterns are much smaller
than BUMPs, so very little scaling was required for me to get
the speckled finish for the cast aluminum surface I wanted.  (I've
pasted my texture call-outs below.)  Evidently GRANITE
works on some kind of inverse relation, because I have to make
the scale value smaller to make the patterns appear larger
(and thus my surface rougher).

Thanx,
KDJ
Who Can Now Make Pretty Pictures of Aluminum Castings  :]


// My Cast Aluminum Textures.
// These textures use the Chrome_Metal texture
// from POV-Ray's default textures file.  Be 
// sure to include both where required.
// A higher number after the name means a rougher
// surface finish on the casting.     
// B-series uses Aluminum instead of Chrome_Metal,
// looks too brownish in colour (brutal heat treat?).
// Kyle D. Jackson, 16 October 2000.


#declare Cast_Aluminum1 = 
texture {
    Chrome_Metal
    normal {
     granite 0.2
     scale 1
    }
}

#declare Cast_Aluminum2 = 
texture {
    Chrome_Metal
    normal {
     granite 0.2
     scale 0.5
    }
}

#declare Cast_Aluminum3 = 
texture {
    Chrome_Metal
    normal {
     granite 0.2
     scale 0.1
    }
}

#declare Cast_AluminumB1 = 
texture {
    Aluminum
    normal {
     granite 0.2
     scale 1
    }
}


#declare Cast_AluminumB2 = 
texture {
    Aluminum
    normal {
     granite 0.2
     scale 0.5
    }
}

#declare Cast_AluminumB3 = 
texture {
    Aluminum
    normal {
     granite 0.2
     scale 0.1
    }
}

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