POV-Ray : Newsgroups : povray.unofficial.patches : media method 3 jitter 0 performance branch off release/v3.8.0. : Re: media method 3 jitter 0 performance branch off release/v3.8.0. Server Time
29 Nov 2022 13:01:18 EST (-0500)
  Re: media method 3 jitter 0 performance branch off release/v3.8.0.  
From: William F Pokorny
Date: 7 Apr 2018 04:09:50
Message: <5ac87cce$1@news.povray.org>
On 04/06/2018 01:44 PM, clipka wrote:
> Sorry, I'm a bit late in replying to this one.
> 
> Am 18.02.2018 um 16:40 schrieb William F Pokorny:
> 
                                  s
>> Note: I recommend jitter alway  be 0 given our current implementation
>> unless a noisy, expensive to AA result is what you want.
> 
> I'm a bit reluctant to throw jitter overboard entirely (even for an
> individual sampling method, particularly the default one). 

Agree given it already exists as is and folks have likely used it in 
scenes. I have it still in my sandbox media branches.

> When a scene
> contains other sources of image noise anyway (such as subsurface light
> transport, jittered area lights, blurred reflections or focal blur),
> increasing media jitter may actually be a better choice performance-wise
> than cranking up the media sampling quality parameters.
> 

If rendering a non-uniform density accurately is your aim, I don't agree 
with the last of this sentence for method 3 jitter. Method 3 jitter is 
expensive noise.

Jitter tends to help 'resolve non-unform media densities' with methods 1 
& 2. Jitter often helps as an option implemented in other than media. In 
those cases jitter amounts to less uniform sampling toward a still 
accurate result. In method 3, jitter - as implemented today - acts 
against the sampling approach even aside from github issue(s): 
https://github.com/POV-Ray/povray/issues/348.

Elsewhere - or maybe only as a thought floating about my head - I've 
suggested a new method 3 aa_jitter feature might be useful. This a 
jitter with an effect more in line with jitter in the other two media 
methods. I wouldn't be free to method 3 performance of course...

Bill P.


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