I'm trying apply a light source of constant density and illumination to a flat
serface say to the xy face of

box{0 1 pigmnet{color White}}

in the xy plane.

I know that the area light source does not actually contain nxn light sources
but simulates the shadow effect of a mxn grid of point light sources. Am I
correct? Or can I achieve the effect I'm looking for with an area light?

I was thinking of defining

#declare light_box = box {0 1 pigment{color White} translate x*-2 }

and then adding something such as

light_source {
  0.5*x+0.5*y-5*z, color White
  parallel
  point_at 0.5*x+0.5*y
  looks_like{light_box}
}

or

  light_source {
  0.5*x+0.5*y-5*z, color White
    projected_through{light_box}
  }

So whats the dealeo with the Area Light?

Is there another way to do this that I'm not thinking of?

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Woody nous illumina en ce 2008/05/02 08:29 -->
> I'm trying apply a light source of constant density and illumination to a flat
> serface say to the xy face of
> 
> box{0 1 pigmnet{color White}}
> 
> in the xy plane.
> 
> I know that the area light source does not actually contain nxn light sources
> but simulates the shadow effect of a mxn grid of point light sources. Am I
> correct? Or can I achieve the effect I'm looking for with an area light?
Correct for the shadows. The highlights are those of a regular point light.
> 
> I was thinking of defining
> 
> #declare light_box = box {0 1 pigment{color White} translate x*-2 }
> 
> and then adding something such as
> 
> light_source {
>   0.5*x+0.5*y-5*z, color White
>   parallel
>   point_at 0.5*x+0.5*y
>   looks_like{light_box}
> }
This simulate a light that is situated at a very large distance. All shadows 
cast are parallel. Specular highlights are those of a point light.
> 
> or
> 
>   light_source {
>   0.5*x+0.5*y-5*z, color White
>     projected_through{light_box}
>   }
This create a beam shaped like the projected through object. Don't affect 
highlights. The projected_through object is automaticaly affected by "no_image" 
"no_shadow" and "no_reflection" so that it's not visible. Works somewhat like an 
arbitrary shaped spotlight with an extreme tightness.
> 
> So whats the dealeo with the Area Light?
> 
> Is there another way to do this that I'm not thinking of?
> 
> 
> 
> 
If you want a broad specular highlight you can do one or some of the following:
If using specular, use a large roughness value. If using phong, use a small 
phong_size value. This simulate broared circular lights as well as rougher 
surfaces. Affect all highlights by any source. (kwick and dirty, good for testing)

You can use an array of, say 2 by 2 or 3 by 3, area_lights. Use adaptive 0 
unless you have artefacts in your shadows.(Slower than a single area_light but 
still reasonably fast)

You can try the version 3.7 beta and add "area_illuminate".

You can use radiosity and give the light_box finish a high ambient value.(slow) 
Then, you add some reflection to your objects so that you can see the light_box 
on them. Use a low value for the reflection.(A bit slower still) Add some blured 
reflection to make the "highlight" more fuzzy. (Very Slow) Use only for the very 
last tests and final render.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you've gained twenty pounds 
sitting at the computer, but can't tell because your beard covers your stomach.
Taps a.k.a. Tapio Vocadlo

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Thanks Alain ! I nominate you for the title of POVRAY Guru!

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Woody nous illumina en ce 2008/05/02 12:34 -->
> Thanks Alain ! I nominate you for the title of POVRAY Guru!
> 
> 
I can't accept that kind of title. Others are more adept than me in that area.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you look at real clouds and 
criticise their media and radiosity settings.
Tom Melly

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Alain <ele### [at] netscapenet> wrote:
> You can use an array of, say 2 by 2 or 3 by 3, area_lights. Use adaptive 0 
> unless you have artefacts in your shadows.(Slower than a single area_light but 
> still reasonably fast)

> You can try the version 3.7 beta and add "area_illuminate".

  The latter should be considerable faster than the former (and get better
highlights) because it's able to use optimizations which are not possible
if you create separate light sources.

-- 
                                                          - Warp

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Warp nous illumina en ce 2008/05/04 11:56 -->
> Alain <ele### [at] netscapenet> wrote:
>> You can use an array of, say 2 by 2 or 3 by 3, area_lights. Use adaptive 0 
>> unless you have artefacts in your shadows.(Slower than a single area_light but 
>> still reasonably fast)
> 
>> You can try the version 3.7 beta and add "area_illuminate".
> 
>   The latter should be considerable faster than the former (and get better
> highlights) because it's able to use optimizations which are not possible
> if you create separate light sources.
> 
Anytime you don't use version 3.7 beta, using several area_light can be the only 
viable solution. It's obvious that you won't have as good a result.

-- 
Alain
-------------------------------------------------
Fighting for peace is like screwing for virginity.
  - public toilet wall, The Bayou, Baton Rouge , LO

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