Hey Christoph,

> You seem to have put quite some work into that, but you don't seem to know
> very much about the technical aspects of soft shadows in a raytracer in
> general and about the POV-Ray area_light function in particular.

That's true, I have never tried coding a raytracer before (but next year in
college there is a module in computer graphics where I will - looking
forward to it ;)), so I don't have any technical programming knowledge of
how Povray specifically works, or how other raytracers work. I'm just basing
my test visually, on the images I get out of Povray.

> I addition your text does not seem to spend a single word on speed
> issues.

Mostly true. I never say which is faster (Povray's arealight is faster), but
I do say about the macro I wrote "The more lights, the smoother the shadows
you'll get out of the macro, but it will take longer to parse and render,
and it will use up more memory". Not great. In the next update on the
article, I'll include a more detailed comparison of the speed of the two
types of lights (I don't have the renderstats for the scenes any more).

> My suggestion before jumping to quick conclusions would be to:
> - read the relevant sections of the POV-Ray documentation again, a lot of
> the things you write indicate you did not really understand what
> area_lights are about.

Good idea - there probably is something basic I'm missing ;) I'm a little
hazy on the way adaptive works exactly, but seeing as it was disabled for
the main test on the page, I didn't think it mattered. Also, I'm sure my
upcoming module in CG will help out in this regard.

> - read something about the techniques of soft shadows in raytracing in
> general, you seem to think the POV-Team does not know how to implement a
> good area light function...

As I said in the article, I know it's hard to code, and I have not a bad
word to say against the PovTeam. It's just that the behaviour of the
arealight in Povray from what I have seen in my tests seems to deviate
wildly from both reality and from what the documentation would suggest. The
simple macro I coded gave about 98% of the results I was expecting, while
the Povray arealight broke down for every test. Also, as I said in the
article, it's all just my oppinion ;)

> - use POV-Ray more intensively to get a feeling for the necessities when
> really using the program and not just doing theoretical tests.

There is nothing too theoretical about the tests. The Illumination Footprint
would come into effect if you were trying to simulate flat-paneled lighting
near walls. The other two tests come into play if you are trying to simulate
reflective or refractive objects in your scenes. These all seem like fairly
normal applications of a raytracer to me.

> BTW, most of the images are broken because of spaces in the file names.

Yeah, sorry about that, it should be fixed now. It was working for me with
my browser, so I just assumed - oops! All the spaces have been removed. I'd
be interested if you gave the page another look...

Thanks for reading!


John

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