I’ve named this Sven’s Bug because I noticed it running his code posted 
in “15 Shapes Taking Forever” in povray.general
And so he gets his name on something. :-P

There is a difference between renders with and without using Render 
Block Size.
The images are with the windows QUICKRES.INI [800x600, AA 0.3] with and 
without +BS8
I compared them in PaintShop Pro (XOR shows it best)

Ver 3.7.0.msvc10.win64
On Win7

-- 

Regards
     Stephen

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Attachments:
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Preview of image 'svens.png'

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Am 18.02.2016 um 20:29 schrieb Stephen:
> I’ve named this Sven’s Bug because I noticed it running his code posted
> in “15 Shapes Taking Forever” in povray.general
> And so he gets his name on something. :-P
> 
> There is a difference between renders with and without using Render
> Block Size.
> The images are with the windows QUICKRES.INI [800x600, AA 0.3] with and
> without +BS8
> I compared them in PaintShop Pro (XOR shows it best)

Nothing in there that would surprise me.

I see some tiny fluctuations in the results, which are normal -- and a
few more pronounced differences at the objects' edges, which are quite
obviously related to anti-aliasing.

POV-Ray 3.7 performs anti-aliasing at the render block level, /before/
assembling the blocks to an entire image. As a consequence, the decision
to supersample any given pixel not only depends on the neighboring
pixels, but also on whether the pixel is at a block boundary.

Consequently, reducing the render block size, and therefore adding more
block boundaries, will change the behaviour of anti-aliasing, and
increase the risk of aliasing artifacts.

So this is not a bug, just a drawback of how things are implemented.


(Hey, what do you expect if you associate Sven's name with it?! :P)

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Yes, this is truly a good idea to use my name as identifier for this
bug, this way CLipka will enjoy much more having to think about it, and
to work with it. Full support from my side. Now we have implanted my
name even in his mind. Cool! :-D



On 18.02.2016 14:29, Stephen wrote:
> I’ve named this Sven’s Bug because I noticed it running his code posted
> in “15 Shapes Taking Forever” in povray.general
> And so he gets his name on something. :-P

Post a reply to this message

On 2/18/2016 8:38 PM, clipka wrote:
> Consequently, reducing the render block size, and therefore adding more
> block boundaries, will change the behaviour of anti-aliasing, and
> increase the risk of aliasing artifacts.
>
> So this is not a bug, just a drawback of how things are implemented.
>

Within tolerances? Fairy Nough. :)

>
> (Hey, what do you expect if you associate Sven's name with it?! :P)

No! I don't want to think. :)

-- 

Regards
     Stephen

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On 2/18/2016 8:40 PM, Sven Littkowski wrote:
> Yes, this is truly a good idea to use my name as identifier for this
> bug, this way CLipka will enjoy much more having to think about it, and
> to work with it. Full support from my side.

Looks like it is just tolerances but you can't say I did not try.


> Now we have implanted my
> name even in his mind. Cool!:-D
>

I think it was already there. ;)

BTW did not someone else say that it is bad Netiquette to top post?

-- 

Regards
     Stephen

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Am 18.02.2016 um 21:40 schrieb Sven Littkowski:
> Yes, this is truly a good idea to use my name as identifier for this
> bug, this way CLipka will enjoy much more having to think about it, and
> to work with it. Full support from my side. Now we have implanted my
> name even in his mind. Cool! :-D

Someone hand me the Brain Bleach, please...

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Am 18.02.2016 um 22:02 schrieb Stephen:

> BTW did not someone else say that it is bad Netiquette to top post?

At least he's now quoting /at all/ ;)

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On 2/18/2016 9:16 PM, clipka wrote:
> Am 18.02.2016 um 22:02 schrieb Stephen:
>
>> BTW did not someone else say that it is bad Netiquette to top post?
>
> At least he's now quoting /at all/ ;)
>

"One day at a time. Sweet..." ;)

-- 

Regards
     Stephen

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Le 16-02-18 15:38, clipka a écrit :
> Am 18.02.2016 um 20:29 schrieb Stephen:
>> I’ve named this Sven’s Bug because I noticed it running his code posted
>> in “15 Shapes Taking Forever” in povray.general
>> And so he gets his name on something. :-P
>>
>> There is a difference between renders with and without using Render
>> Block Size.
>> The images are with the windows QUICKRES.INI [800x600, AA 0.3] with and
>> without +BS8
>> I compared them in PaintShop Pro (XOR shows it best)
>
> Nothing in there that would surprise me.
>
> I see some tiny fluctuations in the results, which are normal -- and a
> few more pronounced differences at the objects' edges, which are quite
> obviously related to anti-aliasing.
>
> POV-Ray 3.7 performs anti-aliasing at the render block level, /before/
> assembling the blocks to an entire image. As a consequence, the decision
> to supersample any given pixel not only depends on the neighboring
> pixels, but also on whether the pixel is at a block boundary.
>
> Consequently, reducing the render block size, and therefore adding more
> block boundaries, will change the behaviour of anti-aliasing, and
> increase the risk of aliasing artifacts.
>
> So this is not a bug, just a drawback of how things are implemented.
>
>
> (Hey, what do you expect if you associate Sven's name with it?! :P)
>

Is it possible that using antialiasing method 2 could reduce that kind 
of artefacts?
With method 1, you sample the center of each pixel, and compare that 
with the neibors. With method 2, you start with samples at each corners 
that are then compared.

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Well, we can always hunt for more bugs and show them to CLipka. Never
give up. His thanks are certain. :-)

On 18.02.2016 16:02, Stephen wrote:
> Looks like it is just tolerances but you can't say I did not try.

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