clipka <ano### [at] anonymousorg> wrote:
> Am 30.03.2012 00:52, schrieb Crippso:
> > Hi, I'm still struggling to correctly draw simple scenes using fresnel
> > reflection and photons (code below). Any idea why this code doesnt show the box?
> > with ior = 5 I expected to see the box being about 0.44 intensity
>
> It seems to me that you have a severe misconception about what POV-Ray's
> "photons" feature does.
>
> POV-Ray's "photons" feature is a way to model light rays that first
> reflect off a mirror, or get refracted, and then get scattered off a
> diffuse surface into the camere.
>
> It does /not/ model light rays that reflect off a mirror directly into
> the camera. Those are accounted for by the "specular" or "phong" feature
> instead.
>
> (Unfortunately, "specular" and "phong" will not help you either, as they
> currently do not model fresnel falloff. You might be able to pull off
> some stunt with the "aoi" pattern, to blend between textures with
> different "specular" or "phong" parameters, but you'll have to implement
> the fresnel formula yourself in that case.)

thanks Clipka, ok so I try the code below to try and see the fresnel reflected
light from the mirror onto a diffuse disc but it still doesnt work. Am i doing
something wrong?

#local p_start  = 0.1;
#local p_end_final = 0.05;

#local final_eb  = 0.5;
#local final_count = 50000;


#default {finish {ambient 0 diffuse 0}}

global_settings{assumed_gamma 1 max_trace_level 50 photons{count 575000}
radiosity
{
    pretrace_start p_start
    pretrace_end   p_end_final
    count final_count
    low_error_factor .05
    nearest_count 1
    error_bound final_eb
    recursion_limit 3
    minimum_reuse 0.001
    gray_threshold 0.0
    normal on
    }
}

camera{orthographic location <0,0,1> look_at <0,0,-1> angle 90}
light_source{<0,0,1.5>,1.0 parallel point_at <0,0,2>}
box{<-0.5,-0.5,2> <0.5,0.5,3> pigment{rgbt <1,1,1,1>} finish{reflection{0,1
fresnel} conserve_energy}  interior{ior 1.5} photons{target reflection on
refraction on collect on}}
disc{<0,0,-1> <0,0,1> 1 pigment{rgb 1} finish{diffuse 1.0} photons{target
reflection on refraction on collect on}}

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