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30 Jul 2024 08:22:33 EDT (-0400)
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From: jhu
Subject: Volume light?
Date: 18 Jun 2009 17:50:00
Message: <web.4a3ab5b1bafdf834c64c67c0@news.povray.org>
Is it possible to make a single light source act like a box filled with lights?
I've tried using area_light, but that only simulates a plane of lights. The
other option I suppose is to arrange multiple light sources in a box pattern.


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From: jhu
Subject: Re: Volume light?
Date: 18 Jun 2009 18:00:00
Message: <web.4a3ab885c799d7cbc64c67c0@news.povray.org>
OK, I just made a scene with 400 lights crammed into a <.2,.2,.2> sized area. It
renders really slowly compared with using area_light simulating 400 lights. But
area_light doesn't quite give me what I want.


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From: Zeger Knaepen
Subject: Re: Volume light?
Date: 18 Jun 2009 18:30:50
Message: <4a3ac01a@news.povray.org>
look up orient

cu!
-- 
#macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
#end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
_(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com


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From: Tim Attwood
Subject: Re: Volume light?
Date: 18 Jun 2009 21:33:13
Message: <4a3aead9$1@news.povray.org>
In beta area highlights can be turned on with 
the area_illumination keyword in an area light,
but it's still a plane. With orient you can face
that plane to the objects though. Unless the
shape of the lights are really critical that would
be easier. If not you can just use a line of
area lights with area_illumination on.

In 3.6 area lights only effect the shadows,
so you get stuck with multiple lights.


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From: jhu
Subject: Re: Volume light?
Date: 18 Jun 2009 22:10:00
Message: <web.4a3af339c799d7cb7c6878d10@news.povray.org>
Didn't know about the 'orient' keyword. It works, but it's only marginally
faster than a group of lights, at least on the test render.


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From: clipka
Subject: Re: Volume light?
Date: 19 Jun 2009 13:05:01
Message: <web.4a3bc45fc799d7cb7080f32a0@news.povray.org>
"jhu" <nomail@nomail> wrote:
> Is it possible to make a single light source act like a box filled with lights?
> I've tried using area_light, but that only simulates a plane of lights. The
> other option I suppose is to arrange multiple light sources in a box pattern.

If a sphere full of lights - instead of a box - would do what you want, you may
want to try the "circular orient" keywords.


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From: clipka
Subject: Re: Volume light?
Date: 19 Jun 2009 13:35:00
Message: <web.4a3bca5dc799d7cb7080f32a0@news.povray.org>
"jhu" <nomail@nomail> wrote:
> Didn't know about the 'orient' keyword. It works, but it's only marginally
> faster than a group of lights, at least on the test render.

You'll find out the difference if you're going for high quality and make use of
the "adaptive" keyword.

The combo

  area_light MyDiameter * x, MyDiameter * y, 9, 9
  adaptive 1
  jitter
  circular orient

(sometimes using "adaptive 0" instead) is my personal favorite for major light
sources in any scene. To get the same quality from individual lights, you'd have
to use a spherical arrangement of several hundred individual light sources
(about a hundred just to make up for the maximum resolution of the area light,
plus plenty more to make up for the additional smoothing effect of the "jitter"
keyword), while the speed is much closer to that of about 10 individual lights.


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