> No.  The problem with blurred reflection is not a resolution problem, if 
> it was you could render the scene at larger size (without aa) and get a 
> nice image.  Blurred reflections is about blur, i.e. averaging of color 
> values.  This is not unrealistic at all, in real life the averaging is 
> mostly matter of interference, diffraction, etc.
> And aa is not designed to generate blur, it is meant to diminish 
> aliasing artefacts due to the discrete sampling of an image.  The effect 
> that it generates blur in your images is in fact only an unintended side 
> effect.

But isn't this the case: if I render an image much larger and view it 
from _large enough distance_ (where the individual pixels/"grains" can't 
be perceived by the eye) I will see only good smooth blur on 
reflections, not grains. And on the other hand, if our eyes had infinite 
resolution, the blurred reflections in real life would be quite 
different looking. This is not about AA generating the blur, but makeing 
it look realistic as it would look in real life. But then again, I have 
not ever looked through the microscope at a blurry reflecting surface, 
but somehow I still think a single normal pattern is more realistic 
approach.

Severi S.

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In article <vcs### [at] tritonimagicode>,
 Christoph Hormann <chr### [at] gmxde> wrote:

> No.  The problem with blurred reflection is not a resolution problem, if 
> it was you could render the scene at larger size (without aa) and get a 
> nice image.  Blurred reflections is about blur, i.e. averaging of color 
> values.  This is not unrealistic at all, in real life the averaging is 
> mostly matter of interference, diffraction, etc.

A blurred reflection is the result of small surface features causing a 
reflections from nearby points on the surface to go in different 
directions. The area of a receptor in the eye covers an area of the 
surface, with many reflections from microfacets. And this is exactly 
what antialiasing is intended to do...it samples the area covered by a 
pixel, rather than a single point. Micronormals combined with very high 
supersampling would be the most accurate method. However, supersampling 
the surface geometry is usually a waste of time, as well as the diffuse 
and highlight aspects of the texture, so a method that samples only the 
reflections would be quite a bit more efficient.

There is a blurring effect in the eye and brain, which is why things 
like dithering work, but it results in a grainy appearance even when 
individual features can not be perceived. You can tell sand, salt, and 
sugar are granular even when you can't see individual grains. Objects 
that appear to have a smooth blurryness to their reflections have 
surface features too small for this to come into play.

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In article <3ffb75ea$1@news.povray.org>,
 Severi Salminen <sev### [at] NOT_THISsibafi> wrote:

> No, I just think "specific" is more appropriate word here than "based". 
> I'm talking about the same thing, English is just not my native language :-)

I agree...it isn't based on the object, it is just specific to the 
portions of the image where that object is visible.

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In article <3ffb74d6$1@news.povray.org>,
 Severi Salminen <sev### [at] NOT_THISsibafi> wrote:

> The easiest approach would be to apply higher AA to objects that the 
> rays hit first. I don't think there would be any need for "2nd or more 
> generation" object specific AA. So if the ray hits a transparent object 
> with higher AA, then we would AA only that specific point no matter what 
> objects there are behind (with whatever AA settings). Basically this is 
> same as 2D AA map based on regions - I think?

One problem...media containers, windows, and other low-visibility 
transparent surfaces. And you can't just pick the highest AA settings 
hit...maybe you have a scene with a starry sky, and want lower settings 
there so they don't get AA'd into oblivion. You'd want to be able to 
exclude such objects, or maybe use the first hit that specifies a 
per-object AA setting rather than the first hit. But then, what's the 
first hit with an AA setting? Are reflections ignored? Say you have a 
highly reflective window into another room. The other room has an object 
with one custom AA setting, the room you're in has an object with 
another custom setting, and the reflection of that one overlaps the 
transmitted image of the other.

Maybe it would be possible to separate the antialiasing of shape 
geometry, texture, reflection, and transparency...but the system starts 
to get a lot more complex. And what do you do at the edges? Say you have 
a high-AA object partially in front of a no-AA object...

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> One problem...media containers, windows, and other low-visibility 
> transparent surfaces. And you can't just pick the highest AA settings 
> hit...

I think picking the highest AA setting along the path of the ray would 
be the easiest to implement and would work in many situations quite 
well. The overall setting would be the minimum and object specific 
settings would only increase this. Then there would not be any means to 
lower AA settings for certain objects below the overall AA settings but 
is that a big problem? There would still be a possibility to lower the 
overall settings.

Severi S.

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"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> In article <3ffb75ea$1@news.povray.org>,
>  Severi Salminen <sev### [at] NOT_THISsibafi> wrote:
>
> > No, I just think "specific" is more appropriate word here than
"based".
> > I'm talking about the same thing, English is just not my native
language :-)
>
> I agree...it isn't based on the object, it is just specific to the
> portions of the image where that object is visible.

   ....and that to me, sounds like a better idea.

     Steve

>
> -- 
> Christopher James Huff <cja### [at] earthlinknet>
> http://home.earthlink.net/~cjameshuff/
> POV-Ray TAG: <chr### [at] tagpovrayorg>
> http://tag.povray.org/

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news:2rp### [at] tritonimagicode...

> I understand that per object settings seem like an exciting feature for
> the user because they seem straight away to set up but i have my doubts
> about the usefulness.  Maybe you could post a sample of using this
> feature in C4D.

See my post in p.advanced-users.

G.

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In article <4h9### [at] tritonimagicode>,
 Christoph Hormann <chr### [at] gmxde> wrote:

> A remark on blurred reflection: a useful feature would probably an 
> adaptive sampling technique for this purpose - you send out a set of 
> rays from the surface of the reflective object and stop if their 
> returned colors do not differ more than  a certain threshold - otherwise 
> you send more rays.

Or until the variance drops below some value. Focal blur uses such an 
adaptive algorithm, it could probably be adapted to blurred reflection.

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Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
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I didn't exactly add this suggestion to the Q&T, but some updated
information has been added to the blurred reflection trick text due to
many valid points in this thread.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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>  I didn't exactly add this suggestion to the Q&T, but some updated
> information has been added to the blurred reflection trick text due to
> many valid points in this thread.

Thanks for additions! Now it basically covers both approaches.

Severi S.

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