i dont get it or the help file is inconclusive !!

AXIS_1_VECTOR, AXIS_2_VECTOR, Size_1, Size_2

referring to "size"
"There is no point in using circular with linear area lights or area lights
which have a 2x2 size."
.. .
.. .     that's already circular.
suggesting "size" = n lights.
and the vector length = array dimensions

so I'm still not sure, also it to alludes to adaptive n = n lights.

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this line seems conclusive. yes, size == n lights according to this.

"For example area_light x,y,4,4 specifies a 4 by 4 array of lights. If you
specify adaptive 3 it would mean that you should start with a 9 by 9 array. In
this case no adaptive sampling is done. The 4 by 4 array is used.
"
so back to my original question, a million lights, seriously?

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adaptive 0 is still 2x2 (at least)
adaptive 0 does not mean off.
apparently

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updated chessdiff.pov with comments on area_light
  area_light x*15, y*15,3,3
//understate rows and columns, turns off adaptive sampling = not enough lights
// adaptive 0 = 2x2 - 1 3x3 - 2 5x5 - 3 = 9x9

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There are too many references scattered all over the place.

Try this:
http://wiki.povray.org/content/Reference:Light_Source

and maybe increase global ambient illumination if you need "more light".

Sometimes one can spend a whole day doing nothing but playing with lighting.

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Alain Martel <kua### [at] videotronca> wrote:

> When using area_light you should always use adaptive.
> The PRESENCE of adaptive turn the feature on. adaptive 0 DO NOT turn it off.
>
> adaptive 0 start with 4 samples (2 by 2): One at each corners.
> adaptive 1 start with 9 samples (3 by 3): Each corners plus one in the
> middle of each side and the center.
> adaptive 2 start with 25 samples (5 by 5), adaptive 3 with 81 (9 by 9),...
>
> This allow you to use something like this :
>
> area_light 3*x 3*z 1025 1025 adaptive 0
>
> and still have reasonably quick renders with no discernible banding,
> even without jitter.

The details of how area_light actually works is a bit murky to those of us who
don't use it enough or have investigated it in a string of experimental renders
or reading the source code.

In any event, I'm sure Alain isn't suggesting using a million lights.
Due to however area_light works, that 3x3 patch might get split up into a grid
of a million squares - but it doesn't take the same amount of time to render as
a million separate point lights.

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On 11/17/19 8:55 AM, Bald Eagle wrote:

> 
> Sometimes one can spend a whole day doing nothing but playing with lighting.
> 

Matt Damon just told this story on the Bill Simmons podcast:

Kubrick had a model of the Overlook Hotel on a table, and while 
producers and gophers stood around, spent over a week just walking 
around it setting up miniature lights, photographing it, moving lights, 
repeat, for a week.

When he was satisfied, he mathematically scaled up the lights for the 
real production of The Shining.

-- 
dik
Rendered 24,503,731,200 of 40,928,716,800 pixels (59%)

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> i dont get it or the help file is inconclusive !!
> 
> AXIS_1_VECTOR, AXIS_2_VECTOR, Size_1, Size_2
> 
> referring to "size"
> "There is no point in using circular with linear area lights or area lights
> which have a 2x2 size."
> .. .
> .. .     that's already circular.
> suggesting "size" = n lights.
> and the vector length = array dimensions
> 
> so I'm still not sure, also it to alludes to adaptive n = n lights.
> 
> 

AXIS_1_VECTOR, AXIS_2_VECTOR define the extent or dimention of the area 
light.

Size_1, Size_2 define how many samples or sub-light are used to evaluate 
the penumbra.

The samples are evenly spaced along the extent.

When using circular, the array of samples is squashed from it's 
rectangular shape into a circular one. A 2x2 area light is always square.
This sample illustrate the principle of circular VS. regular area_light :
//*************** START *************
#version 3.7;

// render as a square image
// +w1024 +h1024
// +w800 +h800

global_settings{assumed_gamma 1}

plane{-z, -10 pigment{ rgb 1}finish{brilliance 0} }

disc{0,z,10000,0.03}// Mask with a small hole

#declare W=11; // How wide the area light is
#declare N=17; // The number of samples to use
light_source{-10*z rgb<1,0,1>*pow(N,2) area_light W*x W*y N N circular }
// Use pow(N,2) to make the light bright enough to always be seen.
// The intensity is distributed along all the sub-lights.
light_source{-10*z rgb<0,1,0>*pow(N,2) area_light W*x W*y N N }

camera{orthographic location 1*z look_at 10*z up W/2+1.2 right W/2+1.2}
//********** END ***********

It's simply an area_light shining through an opening that is 
intentionally much to small to show the samples pattern.
If you add adaptive, it will show the initial array that will be used.

adaptive 0 start with a 2x2 array
adaptive 1 start with a 3x3 array
adaptive 2 start with a 5x5 array
adaptive 3 start with a 9x9 array

Adaptive only improve performance if the area light have at least twice 
the number of samples than the mi minimal array used.


Alain

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> adaptive 0 is still 2x2 (at least)
> adaptive 0 does not mean off.
> apparently
> 
> 
> 
The only way to turn adaptive OFF is to NOT use the adaptive key word.

In adaptive N, the initial number of samples is :

2^N+1

2^0=1 +1 =2
2^1=2 +1 =3
2^2=4 +1 =5
2^3=8 +1 =9
...

Also, the actual number of samples will follow that same pattern and 
will use the smallest number of samples that is AT LEAST the requested 
number.

area_light x z 4 4 adaptive 0
will actually use a 5x5 array.
area_light x z 6 6 adaptive 0
will use 9x9.

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https://educateinspirechange.org/alternative-news/three-player-chess-just-crazy-sounds/

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