Hi,

There still seems to be a bug (or maybe two) in the (refractive) photons 
code.
It accurs only in very special cases, and is dependent on the texture and 
shape of the object on wich the photons show up, on the position of the 
light_source, the color of the light source, and the color and 
filter/transmit of the refractive object (and maybe some other things i 
didn't notice).

The symptoms are: 
a) bright colored caustics, but the color is not related to the color of 
light_source or photon target (of course, dispersion was not used).
b) holes/circular black spots appear in the caustics. 

Here is a scene with shows the prob.
I tried to eliminate everything that seems to have no effect on the bug.
I'll also post a rendering of this scene in the beta-test.binaries group.

#version 3.5;
#include "functions.inc"

#declare overallscale=10;
#declare cm=0.01*overallscale;
#declare m=1*overallscale;

global_settings                        
{
	assumed_gamma 2
	max_trace_level 50
	photons
	{
		count 10000 jitter .3
	}
}


camera
{
	location <0,30,-50>*cm
	look_at <-3.5,6,0>*cm 
	angle 30
}

light_source 
{
	vnormalize(<2,2,-1>)*m*1 // multiply with .6, and the color will 
go away
	color rgb <1,1,.95>*2
	spotlight point_at <0,10,0>*cm radius 0 falloff 15 tightness 20 
}


#declare Floor=
texture
{
	pigment
	{
		color rgb 1
	} 
	finish
	{
		ambient 0
		reflection .2 // remove this -> black "holes" in caustics 
will go away
	}
}


#declare Sky=
texture
{
	pigment
	{
		color rgb 1
	}
	finish{ambient 1}
}

sphere
{
	0,1*m
	translate y*(1*m)
	texture
	{       
		gradient y scale 2*m
		texture_map
		{
			[0.0 Floor] 
			[0.1 Floor] 
			[0.3 Sky] 
			[1.0 Sky] 
		}
		
	} 
	translate -y*0.01*cm
	inverse
	//clipped_by{plane{y,.02*m }}  
}

lathe
{
	//linear_spline       
	cubic_spline
	6+2+2+1,

	< -0.5,  0.1>*cm,
	
	<  0.0,  0.1>*cm,
	<  4.0,  0.0>*cm,
	
	<  4.75, 0.5>*cm,
	
	<  4.0,  3.0>*cm,
	<  5.0,  10.0>*cm,
	<  5.0,  11.5>*cm,
	<  4.5,  10.0>*cm,
	
	<  3.2,  1.5>*cm,
	
	<  0.0,  1.5>*cm
	
	< -0.5,  1.5>*cm
	
	// avoid coicidence probs
	translate y*.1*cm

	pigment
	{
		color rgb <.99,1,.99>
		filter .9
	}
	interior
	{
		ior 1.5
	}
	photons{target refraction on reflection on collect off} 
}

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