> As I understand it, area lights use an algorithm more like adaptive
> antialiasing than focal blur.

	Yes, that's true, actually the idea is just the same. So I think
one could simply add a tolerance parameter (same effect as when using for
instance +A0.3 in adaptive antialiasing) to the definition of an area_light
- again when using adaptive method. This would replace the default 0.1
difference between the tested rays. I also propose to add an option to
specify either the recursion limit or the maximum number of shadow rays.
The first would be more consistent with the current available options.

	Another point is about a general optimisation of all these different
adaptive sampling methods. When using adaptive antialiasing, every ray hits
different portions on the object surfaces (at least for near objects), so the
shadow rays should be different too, but not *so* different. When using
area_light, at the first recursion level (antialiasing and shadowing), we get
at least 16 rays: 4 from the camera times 4 from the object to each corner of
the area_light. The situation becomes even more expensive for every next
recursion levels.

	Could it be possible to mix the area_light adaptive method with the
antialiasing one ? I understand the situations are different, especially if
the area_light is large enough. But maybe there's some way (approximation) to
save a lot of rays instead of multiplying all the tests required at every
recursion levels.

	Is that simply utopia ? I'm currently using my custom implementation
of a camera motion blur effect (moving camera; based on focal blur method) with
area_lights and adaptive anti-aliasing, and that's hell to render. I suspect a
lot of rays are "wasted" but I didn't yet find an appropriate method to solve that.


*** Nicolas Calimet
*** http://pov4grasp.free.fr

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