POV-Ray : Newsgroups : povray.general : Finite Light Source Server Time
29 Jul 2024 08:21:30 EDT (-0400)
  Finite Light Source (Message 1 to 5 of 5)  
From: Sereib
Subject: Finite Light Source
Date: 15 Aug 2012 07:10:00
Message: <web.502b828530fcd43fd361cc930@news.povray.org>
Hi,

is there any chance to tell POV-Ray that a light-source only has to be
considered, if the distance between light-source and the point where a ray hits
an object is not bigger than R?

If have a scene with hundreds of light-sources which slows down rendering speed.
Due to a high fade_power, each light-source only shows a visual effect on
objects very close to this light-source, but of course also causes calculations
for distant objects.

Thank you!


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From: Christian Froeschlin
Subject: Re: Finite Light Source
Date: 15 Aug 2012 07:30:31
Message: <502b8857@news.povray.org>
Sereib wrote:

> is there any chance to tell POV-Ray that a light-source only has to be
> considered, if the distance between light-source and the point where a ray hits
> an object is not bigger than R?

I proposed such a feature about two years ago but it is not
included in 3.7 (see http://bugs.povray.org/task/118). If you
know how to compile your own version you can have a look at the
minor code change attached to the request.

Otherwise an alternative may be to use light_groups, although
this forces you to do disjoint groups (and is tedious, too).


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From: Sereib
Subject: Re: Finite Light Source
Date: 15 Aug 2012 08:50:01
Message: <web.502b9ac87fc45c71d361cc930@news.povray.org>
Hello,

Thank you! I hoped that there would be such a feature in the existing POV-Ray
version, since it would be rather easy to implement and very useful for certain
scenes. I have no idea nor experience how to build my own version with these
changes, sorry ...

In my special scene, using light-groups is not an option. The scene (a
collection of interconnected neurons) consists on one single blob object
containing millions of spheres, no chance to split this into many blob objects
since the transition between two blob objects is not smooth any more as it
should be, so I have to keep it as single object. Additionally, the blob object
already exists, so I would have to edit the 200 MB big include file ...


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From: Christian Froeschlin
Subject: Re: Finite Light Source
Date: 15 Aug 2012 20:50:38
Message: <502c43de$1@news.povray.org>
Sereib wrote:

> In my special scene, using light-groups is not an option. The scene (a
> collection of interconnected neurons) consists on one single blob object
> containing millions of spheres, no chance to split this

You could of course split the finished object by suitable intersection
with boxes. However, using lightgroups, it will be difficult to achieve
smooth lighting at the seams.


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From: Alain
Subject: Re: Finite Light Source
Date: 18 Aug 2012 00:18:13
Message: <502f1785$1@news.povray.org>

> Sereib wrote:
>
>> In my special scene, using light-groups is not an option. The scene (a
>> collection of interconnected neurons) consists on one single blob object
>> containing millions of spheres, no chance to split this
>
> You could of course split the finished object by suitable intersection
> with boxes. However, using lightgroups, it will be difficult to achieve
> smooth lighting at the seams.

For smooth seams, you'll need to replicate at least part of the lights 
from the first neibouring groups in any given group. It could probably 
be acheived using an area_light to replace several sources from a single 
piece.


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