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From: fls13
Subject: A test-need a little help on lighting
Date: 18 Jan 2006 18:25:00
Message: <web.43cecdfdad0f020a49bfd5320@news.povray.org>
I've got a parallel light positioned outside the window, but it's not
casting light very realistically. What would be the best light type to use
so the light fans out once it passes thru the mesh's "window"?


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From: Alain
Subject: Re: A test-need a little help on lighting
Date: 18 Jan 2006 18:59:17
Message: <43ced655$1@news.povray.org>
fls13 nous apporta ses lumieres en ce 18/01/2006 18:23:
> I've got a parallel light positioned outside the window, but it's not
> casting light very realistically. What would be the best light type to use
> so the light fans out once it passes thru the mesh's "window"?
> 
> 
> ------------------------------------------------------------------------
> 
If you want to simulate the sun, parallel is the best choice, as the "faning" from the
sun is 
negligeable.
A way to improve realism would be to use area_light. Make it circular, use a
relatively dense aray, 
say 17*17 or 33*33, and adaptive 1(use 2 or 3 if there are artefacts). Use a
relatively small 
dimention for the area_light axis, the apparent sun's radius been 0.5 degree.
You can also use some scathering media to make the light beams to show. It will
increase rendering 
time significantly.
Using radiosity will make the bright parts to light-up unlight parts. It will also
increase 
rendering time.

-- 
Alain
-------------------------------------------------
Dachshunds are really small crocodiles with fur.


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From: Kenneth
Subject: Re: A test-need a little help on lighting
Date: 19 Jan 2006 03:25:01
Message: <web.43cf4ba64e4b86d9dbcfc3c90@news.povray.org>
"fls13" <fls### [at] netzeronet> wrote:
> I've got a parallel light positioned outside the window, but it's not
> casting light very realistically. What would be the best light type to use
> so the light fans out once it passes thru the mesh's "window"?

I like your scene; very old-world-looking, just the way I imagine it must
have been like to live in such a place back in medieval days.

To Alain's response, I would add: try using an area spotlight.  It will
render faster than a normal area light, since the rays are confined only to
the visible cone. And then position it FAR away from the window.  (I
haven't tried a scene like yours, though, so I don't really know if the
light will "fan out" correctly, the way you want. Try playing with the
light's distance.)

An example...

light_source {
    0*x
    color <1,1,1>
    spotlight
    translate <...whatever...>
    radius 2 // or something smaller
    tightness 100 // to make its overall cone sharp,
                   // since it's aimed only at the window
    falloff 2.5  // or 2
    point_at <...whatever...>
    area_light <1, 0, 0>, <0, 0, 1>,16,16 // just a guess
    adaptive 1
    jitter
    circular
    orient
  }


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From: Marc Jacquier
Subject: Re: A test-need a little help on lighting
Date: 19 Jan 2006 03:59:46
Message: <43cf5502$1@news.povray.org>

news:43ced655$1@news.povray.org...
> Using radiosity will make the bright parts to light-up unlight parts. It
will also increase
> rendering time.
>
If you use radiosity, dont't forget to set all ambient values to 0.

Marc


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