> > The previous behavior was correct; the current behavior is broken.
>
> That may well be your opinion, but that does not make you statement
correct.

Of course not, which is why I added many paragraphs after that statement to
show why it was correct. It was merely my thesis. =)

> That may well be your opinion, but that does not make you statement
correct.
> Prior to POV-Ray 3.6 what you got when using anti-aliasing was a fancy
> averaged blur of every pixel, not different from scaling down an image
> rendered without anti-aliasing.  That is not all what anti-aliasing is
> about.

I agree that the method through which antialiasing is applied isn't
relevant - whether it's created by rendering a large image and scaling it
down, or through any other method. What *is* relevant is the effect.
Anti-aliasing is, by definition (and by the meaning of the word itself), an
effect to remove aliasing. POV-Ray 3.6's anti-aliasing does not remove
aliasing. Why then is it even called anti-aliasing? It's not doing its job.

> In reality small bright objects do not disappear, ever.  To the contrary.

I wish I understood more about how the human eye works so that I could
better respond to that statement. However, it is important to recognize
that, in the case of stars, a large part of the fact that we can see them is
due to light scattering through the atmosphere as it reaches our eyes. I'm
not sure exactly how tiny the average star would be, but it's probably
smaller than it actually appears. Some stars *are* so far away that the
human eye can't see them. This is probably due to the fact that there is a
limit to the number of photons travelling away from the stars, and with
stars that are far away enough the chances of some of those photons hitting
our eyes is tiny. But all of this has to do with effects that POV-Ray does
not, by default, simulate. Scattering media could be used to make tiny
distant light sources with tiny bright looks_like spheres visible, thus
recreating the appearance of actual stars in the real world. I'm willing to
bet that, if our eyes had resolution comparable to 1024x768, and there were
a really tiny bright object very far away, unaffected by things like light
scattering, we wouldn't be able to see it - no matter how sophisticated our
brain's "anti-aliasing" might be. I think it's very likely that the only
reason we can see far away bright objects is because our eyes have a very
high resolution. Not that our eyes can really be compared to a monitor in
such a simple way.

My point here is that the fact that small bright objects are visible in real
life has nothing to do with samples of light being averaged together, one of
which is much brighter than the others. It's due to a number of other
factors, and POV-Ray 3.6's anti-aliasing is a poor attempt at simulating
those factors with a single calculation.

It could also be pointed out that even with POV-Ray 3.6's antialiasing, many
small bright objects *do* disappear: those which are not hit by the primary
rays, so that supersampling does not occur. 3.6's attempt at simulating the
visibility of distant bright objects is therefore not even very accurate,
and people have to create an exceedingly high number of tiny bright spots in
order to make a much smaller number of pixels white to simulate stars.

None of this addresses the fact that the anti-aliasing is there to remove
aliasing, and not to make tiny bright objects visible. That's not its job.
Its job is to remove aliasing, and it's not doing that.

By the way: tiny, *not* bright objects never disappear either. But they are
not visible in any renderer's output.

> Either way, I suggest to end this fruitless discussion.

You only see the discussion as fruitless because you believe that you are
correct and the people making the "noise" are incorrect. If this discussion
is more than a matter of opinion - that is, if it is based on what is
"correct" and what is "incorrect" - then there is no reason for it to end
until everyone understands what is correct and why. I *am* influenced by log
ic, and if I am presented with a flawless argument that shows me that I am
incorrect, I will stand corrected. I trust you feel the same.

> The decision
> stands as is because it corrects a bug.

I have not seen any evidence that 3.5's anti-aliasing was buggy. It did its
job. If there was a bug with it, then there must be a concrete explanation
for that bug, beyond "it was incorrect." *Why* was it incorrect? As I've
shown, "because it didn't show tiny bright objects" is not an entirely valid
reason. However, "because it doesn't remove aliasing" seems like a very good
reason why 3.6's anti-aliasing is incorrect.

> If you do not like this correction,
> you are free to continue to use POV-Ray 3.5.  Nobody is forcing you to use
> POV-Ray 3.6 after all.

I only argue this point because I want POV-Ray to be the best it can; it is
not for any personal agenda.

 - Slime
 [ http://www.slimeland.com/ ]

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