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From: Kenneth
Subject: Re: Media discrepancy (artifact?)
Date: 8 Jun 2008 00:45:00
Message: <web.484b62aa9a2aa19278dcad930@news.povray.org>
"Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:

>
> Try this code. It is some kind of nebula, which is more accurate for comparison
> between renders than simple spheres...
> PS: I just hope that I am not mislead by something so obvious I can't see it!

Sorry I haven't been timely with my comments; I got kind of 'stuck' while
testing out this version of your nebula code--specifically the version with the
light_groups, the example using just the spheres again. I ran across a
light_group problem that I haven't been able to understand or work around.

Given that your light_group code, as-is, has two groups of spheres, each group
in its OWN light_group (and each with its own light): If I comment-out the
light_group container for the UnionSpheres group...while retaining its light..
suddenly *those* spheres appear to be lit by BOTH lights! Yet the
DistinctSpheres group does not (which is correct behavior.) I don't understand
why the light in the DistinctSpheres light_group is now illuminating BOTH
groups of spheres. Aarrgghh, now I'm hoping that *I* am not being mislead by
something obvious!  :-) Looks like some kind of problem with lights_groups...to
add to the scattering media problems!

BTW, I haven't yet said how much I like your nebula(s). Nice work! I've even
learned a few things; thanks!

Ken W.


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From: Bruno Cabasson
Subject: Re: Media discrepancy (artifact?)
Date: 10 Jun 2008 19:15:51
Message: <op.ucj2wkrcm1sclq@pignouf>
Le Sun, 08 Jun 2008 06:40:10 +0200, Kenneth <kdw### [at] earthlinknet> a  


> "Bruno Cabasson" <bru### [at] alcatelaleniaspacefr> wrote:
>
>>
>> Try this code. It is some kind of nebula, which is more accurate for  
>> comparison
>> between renders than simple spheres...
>> PS: I just hope that I am not mislead by something so obvious I can't  
>> see it!
>
> Sorry I haven't been timely with my comments; I got kind of 'stuck' while
> testing out this version of your nebula code--specifically the version  
> with the
> light_groups, the example using just the spheres again. I ran across a
> light_group problem that I haven't been able to understand or work  
> around.
>
> Given that your light_group code, as-is, has two groups of spheres, each  
> group
> in its OWN light_group (and each with its own light): If I comment-out  
> the
> light_group container for the UnionSpheres group...while retaining its  
> light..
> suddenly *those* spheres appear to be lit by BOTH lights! Yet the
> DistinctSpheres group does not (which is correct behavior.) I don't  
> understand
> why the light in the DistinctSpheres light_group is now illuminating BOTH
> groups of spheres. Aarrgghh, now I'm hoping that *I* am not being  
> mislead by
> something obvious!  :-) Looks like some kind of problem with  
> lights_groups...to
> add to the scattering media problems!
>
> BTW, I haven't yet said how much I like your nebula(s). Nice work! I've  
> even
> learned a few things; thanks!
>
> Ken W.
>
>
>


Thanks for you attention, Kenneth. Me neither, I had not much time these  
days to dig more on the subjet. I hope I have more time this week-end to  
meditate on it. I'll have a try at the light_group concern you mention.

    Bruno.
-- 

http://www.opera.com/mail/


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