Am 29.12.2016 um 23:42 schrieb PerroNoob:
> I'm trying to render a long rectangle (with some extra stuff) using an area
> light. The problem is that I always see a dark background, even if I extend the
> area light further along the z direction. If I change the perspective, I also
> see that extending the area light region does not have much effect, there is
> always a darker side on the rectangle, which I don't know why. I've also tried
> increasing the height (y direction) of the area light with a better result,
> however the shadows are smaller in that case.
> 
> What I want is to make most of the floor and background as white as possible but
> without making the rectangle to look too bright (that's why I use a gray
> background).

I'm not sure I correctly understand what you're trying to describe, but
I have a hunch that "area_illumination on" might be what you want.

Without that, area lights only affect the boundary of shadows, while
still acting like point lights with regards to how bright unshadowed
surfaces appear. So if your area light is 1000 x 1 meters, and only a
meter away from a surface, you only get a perfectly symmetric bright
spot near the light source's nominal center, rather than the expected
bright stripe along the whole length of the area light, because this
dimming is not due to shadows but due to the angle at which the light
hits the surface.

"area_illumination" was specifically introduced to fix this.

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