POV-Ray : Newsgroups : povray.pov4.discussion.general : Suggest moving AA methods 1 & 2 jitter to stochastic RNG Server Time
18 Jul 2024 09:53:58 EDT (-0400)
  Suggest moving AA methods 1 & 2 jitter to stochastic RNG (Message 1 to 1 of 1)  
From: William F Pokorny
Subject: Suggest moving AA methods 1 & 2 jitter to stochastic RNG
Date: 16 Jan 2024 05:29:22
Message: <65a65a82$1@news.povray.org>
With the yuqk fork, moved the jitter option of AnitAlias(AA) methods 1 & 
2 to the same stochastic random number generator used already with 
method 3 (boost::mt19937 2d double). Updates should be in R11 v0.6.5.0.

With this update, comes the ability to use Stochastic_Seed=n / +SSn with 
yuqk's methods 1 & 2 jitter for render to render stability.

The yuqk fork has for some years run method 1&2 jitter again with random 
2D vectors. This matching earlier POV-Ray behavior and the jitter 
default is again off. See previous posts about the fixed set of jitter 
samples currently in use with v3.7/v3.8 having shortcomings. Basically, 
+-j with v3.7 / v3.8 is different, but only 'maybe' better or worse with 
or without jitter for any given scene.

Lastly, enabled big jitter with method 3 too. Unlike methods 1 & 2 it is 
not scaled smaller on the AA depth (+r). So, for sampling bleeding 
slightly into adjacent pixels, use say, +j1.1. In other words, with 
method 3 it's a scaling factor applied to the random sampling that is 
'always' done over the entire square pixel with method 3.

Bill P.

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