Bruno Cabasson nous apporta ses lumieres en ce 25/10/2006 06:02:
> It was just experimenting.
> 
> I fixed the problem: I have to specify 'media_interaction off' for my
> light_source. By doing this the white part of the beam before the lens (not
> refracted yet) disappears. Apparently, no photons are deposited in this area
> if the light has not been refracted (or reflected, I guess), I can't see
> exactly why. Thus, I had to put a thin cylinder of glass with 'target' and
> 'refraction on' for photons in front of the light_source.
Photons are not computed before the first reflection or passage thrue the first 
transparent object with a target photon item. This save rendering time.
> 
> cylinder
> {
>   0, 0.01*z, 1.2*LIGHT_RADIUS
>   hollow
Not needed, don't have any effect.
>   pigment {rgbt 1}
>   interior {ior 1.0}
Here, you don't need interior. ior 1 is the default value.
>   translate -5*z
>   photons {target collect off refraction on reflection on}
> }
> 
> What this experiment tends to show is that photons are deposited in media
> only if the light has been already refracted or reflected at least once
> before reaching the current location. Am I right?
You are.
> 
> But this does not explain the artifact in the first case (with
> 'media_interaction on'). Could it be an 'extinction' side-effect of the
> media though I specified zero?
It's the edges of the light's cylinder.
> 
> I also noticed that, when using media photons and in the sorting phase of
> the parse, the status bar displays a wrong number of sorted photons.
> 
> 
> I join here another experiment. I am quite happy with the path of the red
> beam in the first lens. However, I wonder why there is a gap between the
> incident rays and relected rays on the mirrors. Suggestions welcome. And
> there is something strange at the end where the remaning beams converge.
> 
> 
> ------------------------------------------------------------------------
> 
By default, there are 7 dispersion samples and you have 7 beams. Try increasing 
dispersion_samples.
You mean the black strip cuting the light after the second lens? Don't know.

-- 
Alain
-------------------------------------------------
Don't let your mind wander -- it's too little to be let out alone.

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