POV-Ray : Newsgroups : povray.binaries.images : No antialiasing around shadows? Server Time
13 Nov 2024 20:12:53 EST (-0500)
  No antialiasing around shadows? (Message 1 to 8 of 8)  
From: SharkD
Subject: No antialiasing around shadows?
Date: 19 Jun 2010 19:35:18
Message: <4c1d5436@news.povray.org>
I just rendered the following scene and noticed that no antialiasing 
appears around the shadow edges, despite having the feature turned on. 
There does seem to be antialiasing going on where the objects meet the 
background though. Is this a bug?


-- 
http://isometricland.com


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From: Thomas de Groot
Subject: Re: No antialiasing around shadows?
Date: 20 Jun 2010 03:42:53
Message: <4c1dc67d$1@news.povray.org>
"SharkD" <pos### [at] gmailcom> schreef in bericht 
news:4c1d5436@news.povray.org...
>I just rendered the following scene and noticed that no antialiasing
> appears around the shadow edges, despite having the feature turned on.
> There does seem to be antialiasing going on where the objects meet the
> background though. Is this a bug?
>

IIrc, high-contrast edges are more difficult to aa. What is you aa value? In 
this case you might need +a0.1 or even +a0.01

Thomas


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From: SharkD
Subject: Re: No antialiasing around shadows?
Date: 20 Jun 2010 05:17:00
Message: <4c1ddc8c$1@news.povray.org>
On 6/20/2010 3:42 AM, Thomas de Groot wrote:
> "SharkD"<pos### [at] gmailcom>  schreef in bericht
> news:4c1d5436@news.povray.org...
>> I just rendered the following scene and noticed that no antialiasing
>> appears around the shadow edges, despite having the feature turned on.
>> There does seem to be antialiasing going on where the objects meet the
>> background though. Is this a bug?
>>
>
> IIrc, high-contrast edges are more difficult to aa. What is you aa value? In
> this case you might need +a0.1 or even +a0.01
>
> Thomas
>
>

I'm using AA 0.3. I guess if there's a good reason then there's no real 
problem.

-- 
http://isometricland.com


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From: clipka
Subject: Re: No antialiasing around shadows?
Date: 20 Jun 2010 11:42:19
Message: <4c1e36db$1@news.povray.org>
Am 20.06.2010 01:35, schrieb SharkD:
> I just rendered the following scene and noticed that no antialiasing
> appears around the shadow edges, despite having the feature turned on.
> There does seem to be antialiasing going on where the objects meet the
> background though. Is this a bug?

No, it's just the way AA currently works.

In POV-Ray 3.6 with assumed_gamma 1.0, and POV-Ray 3.7 until beta 37a, 
AA is based on linear brightness differences; however, the perception of 
aliased details follows quite non-linear rules. As a result, you either 
get visible aliasing artifacts at edges between moderately-dark and 
very-dark areas, or waste a lot of time "over-anti-aliasing" edges 
between moderately-bright and very-bright areas.

Future versions of POV-Ray will therefore use a non-linear 
(gamma-law-based) threshold for anti-aliasing.

(Earlier versions of POV-Ray, as well as POV-Ray 3.6 with assumed_gamma 
2.0, also effectively used a gamma-law-based anti-aliasing threshold and 
were therefore less prone to such artifacts, but this was just a side 
effect of the absent gamma handling.)


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From: Thomas de Groot
Subject: Re: No antialiasing around shadows?
Date: 21 Jun 2010 04:01:18
Message: <4c1f1c4e$1@news.povray.org>
"clipka" <ano### [at] anonymousorg> schreef in bericht 
news:4c1e36db$1@news.povray.org...
> Future versions of POV-Ray will therefore use a non-linear 
> (gamma-law-based) threshold for anti-aliasing.

including version 3.7?

Thomas


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From: clipka
Subject: Re: No antialiasing around shadows?
Date: 21 Jun 2010 08:18:21
Message: <4c1f588d$1@news.povray.org>
Am 21.06.2010 10:01, schrieb Thomas de Groot:
> "clipka"<ano### [at] anonymousorg>  schreef in bericht
> news:4c1e36db$1@news.povray.org...
>> Future versions of POV-Ray will therefore use a non-linear
>> (gamma-law-based) threshold for anti-aliasing.
>
> including version 3.7?

including next beta, actually.


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From: Thomas de Groot
Subject: Re: No antialiasing around shadows?
Date: 21 Jun 2010 10:18:51
Message: <4c1f74cb@news.povray.org>
"clipka" <ano### [at] anonymousorg> schreef in bericht 
news:4c1f588d$1@news.povray.org...
> Am 21.06.2010 10:01, schrieb Thomas de Groot:
>> "clipka"<ano### [at] anonymousorg>  schreef in bericht
>> news:4c1e36db$1@news.povray.org...
>>> Future versions of POV-Ray will therefore use a non-linear
>>> (gamma-law-based) threshold for anti-aliasing.
>>
>> including version 3.7?
>
> including next beta, actually.

Excellent! You guys are fantastic, and no joke.

Keep up the good work!

Thomas


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From: Alain
Subject: Re: No antialiasing around shadows?
Date: 27 Jun 2010 14:22:07
Message: <4c2796cf$1@news.povray.org>
Le 2010-06-19 19:35, SharkD a écrit :
> I just rendered the following scene and noticed that no antialiasing
> appears around the shadow edges, despite having the feature turned on.
> There does seem to be antialiasing going on where the objects meet the
> background though. Is this a bug?
>
>

Dark green against black.
Maybe you don't have enough contrast for the antialiasing to kick off.
If the red and blue are zero and the green less than 0.3, then you stay 
under the aa threshold.


Alain


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