Hello Alain,

thanks for your answer.

Alain <ele### [at] netscapenet> wrote:
> This is due to the fact that area_light are composed of several point_lights
> disposed in a regular array. Some shadowed points may be in view of all of
> those points.

Yes, I figured out this was the problem, but I am not sure how to get rid of
it ;)

> The use of jitter can help hide this, as for each points tested, the location
> of  each element is slightly shifted randomly from it's original position for
> the shadow evaluation. This random noise is normaly unnoticeable.

I did use jitter, too.
Well, let me clarify, this is my test scene:


#include "colors.inc"
#include "textures.inc"
plane { y, 0
  pigment { rgb .8 }
  finish { reflection .05 }
}
cylinder { <0,0,0>,<0,1,0>,.03
  texture { Chrome_Metal }
}
#declare qualight=clock;
light_source { <6, 4, 0> White
  area_light <3, 0, 0>, <0, 0, 3>, qualight, qualight
  jitter
  circular orient
}
camera {
  location <0, 2, -2>
  look_at <-1.2, 0, 0>
}


You can see the result here: http://www.tasuki.org/povray/arealights.png

For some number of lights, it looks ok... but the problem appears again when
I have more sticks at different distances from the area light...

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