POV-Ray : Newsgroups : povray.advanced-users : Speeding up media : Re: Speeding up media Server Time
5 Jul 2022 23:51:30 EDT (-0400)
  Re: Speeding up media  
From: Ash Holsenback
Date: 15 Feb 2021 12:39:57
Message: <602ab1ed$1@news.povray.org>
On 2/15/21 6:00 AM, William F Pokorny wrote:
> On 2/15/21 2:37 AM, Thomas de Groot wrote:
>> Op 14/02/2021 om 20:38 schreef Ash Holsenback:
>>> On 2/14/21 2:33 PM, Ash Holsenback wrote:
>>>> On 2/14/21 12:32 PM, Alain Martel wrote:
>>>>> Le 2021-02-14 à 11:02, Ash Holsenback a écrit :
> ...
>> Give that man a beer!
>>
>> Much better assuredly.
>>
>> Pending more learned answers on your last question, I would be wary to 
>> affirm this. The point being probably - if those are silently ignored 
>> by method 3 as Alain states - that people will wring themselves into 
>> hoops only to see some 'improvements' to their media, without any 
>> results obviously. If, on the other hand, those are /not/ ignored, we 
>> need to be dead sure about it. What does the code say, Mr Pokorny?
>>
> 
> Generally, I recommend we make the recommendation to use only media 3 
> more strongly. Using the other methods with the current code base is 
> potentially confusing given they won't get some of the normal defaults 
> due how the flip to method 3 was done in the parsing phase.
> 
> I agree with Alain. The keywords: confidence, variance and ratio are 
> used only with methods 1 and 2 (a). The use of the variance word in the 
> method 3 wording is I suppose correct, but unfortunate. Another sample 
> is taken between two existing, if the difference between the two end 
> samples is > the aa_threshold.
> 
> (a) For the purposes of documentation see (a1) and ignore the rest of 
> this footnote. Someone can set the intervals in method 3 to more than 1 
> and if they do ratio does come into play with a lit and un-lit intervals 
> scheme internally which 'probably' doesn't have much of an end effect 
> for method 3, but... Always true, sometimes, almost never, never? Not 
> sure... When using multiple medias with mixed sampling types, I know of 
> some bleed through in the keyword settings between methods.
> 
> (a1) It would be good to somewhere add a note along the lines of: When 
> using multiple medias, it's strongly recommend all use the same sampling 
> method. With the current code there is some keyword setting bleed 
> between methods.
> 
> Aside: The sentence about monte carlo.... only applies to methods 1 and 2.
> 
> Aside: FWIW. In povr I plan to at least make it appear methods 1 & 2 and 
> their keywords do not exist at all (and I'll pull jitter from media 3). 
> Ideally, I'll replace the whole of the current implementation with a new 
> media 3 like one. There are standing issue with media 3 too with respect 
> to speed, accuracy of result and when and if adaptive sampling actually 
> kicks in. But, it's media - which is fuzzy. Most remaining issues don't 
> matter much to an end result as I recall - so long as we sample enough 
> that things look good. ;-)
> 
> Bill P.
> 
> 

thanks /everyone/ for guidance and support... please review
http://wiki.povray.org/content/Reference:Sampling_Parameters_%26_Methods


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