I just wanted to say a quick word or two in defence of John and his
article.

    I can remember when I first discovered POVs area-lights and being hugely
disappointed by the results. I wanted a fluorescent strip light in my scene,
I quickly dug into the docs and found the funky area_light thing, tried it,
and it just didn't look right - I had the strip light close to a wall and
spotted the same 'the light seems to be coming from the center of the strip,
not all along it' effect.
    Ok, I later read the documentation in more depth and realised that
area_lights were never designed for the effect that I wanted and in the end
I produced something similar to John's 'truAreaLight' solution.
    But my initial reaction on reading the docs was exactly the same a
John's - 'these area_light things just don't behave realistically' - and the
very fact that Warps misconceptions page needs a section on area lights
(though, I note it insists that the results you get from an area light are
'practically identical' to an array of point lights) shows that we're not
the only two people to have had misconceptions about what area_lights are
meant to do and how they are meant to behave.

    I think there is a need in POV for a more realistically modelled 'area
light' (for the want of a better term) and John's Photon Challenge images
neatly demonstrate why - so what if it renders more slowly - people are
going to quickly learn that 'truAreaLights' (to use John's nomenclature)
kill render time, just as we all quickly came to understand that
antialiasing produces a big hit on render time - when it does produce more
realistic lighting effects ?

    Everything in POV is to some degree optional, and to some degree affects
render time, and it is up to us to decide where and when we choose to use
each feature to achieve the results we desire. I do not see why there would
be any problem in implementing an optional, more realistic, model of 'area
lights' in POV - there clearly is a need for it - and it could, I would have
thought, also benefit from optimisations and techniques that the 'create an
array point lights' solution can not.

--
Pandora/Scott Hill/[::O:M:C::]Scorpion
Software Engineer.
http://www.pandora-software.com

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