After reading the thread in p.a-u on are lights, I decided to experiment.
In the attached images I tried three different light schemes, a single point
light, an area light and an array of point lights.
The lights are all in the same location, 50 units above a 50 unit sphere
(with phong highlighting)
The arealight and array of point lights have the same number of lights and
are the same size, 8x8 lights, over a 150x150 unit area (area light w/o
jitter)
The white balls show the positions of the lights in each
The images are:
PLight.png - single point light
ALight.png - area light
APLight.png - array of area lights

As the images show, area lights do not work quite as one would expect (but
that is not to say they do not work as intended*).
The point light (for comparison) shows clearly the hard shadow of the
sphere, the hard shadowline (separating the dark and illuminated sides of
the sphere) and the phong highlight.
The area light shows the correct 'soft shadowing' of the sphere, however,
the phong highlight is identical to that of the point light and the
shadowline is similar save for a bit of softening. (*This is how it is
intended to work though, according to the docs)
The array of area lights, on the other hand, shows closer to what would be
expected in real life, the soft shadows (similar to that of the area light),
but also the phong highlight shape (perhaps not as bright as it should be,
due to light intesities used) and most importantly, the shadowline.

For objects that are relatively far/large compared to the arealight, the
shadowline effect is not significantly noticeable, but in a situation such
as this, where the object is near/small compared to the area light, the
difference is quite noticeable.

Any other comments on this?

-tgq

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Attachments:
Download 'APLight.png' (17 KB) Download 'ALight.png' (15 KB) Download 'PLight.png' (9 KB)

Preview of image 'APLight.png'

Preview of image 'ALight.png'

Preview of image 'PLight.png'