POV-Ray : Newsgroups : povray.advanced-users : Speeding up media : Re: Speeding up media Server Time
22 Jan 2022 19:46:36 EST (-0500)
  Re: Speeding up media  
From: Alain Martel
Date: 11 Feb 2021 10:45:30
Message: <6025511a$1@news.povray.org>
Le 2021-02-09 à 02:30, Thomas de Groot a écrit :
> Op 08/02/2021 om 16:16 schreef Alain Martel:
>> Le 2021-02-07 à 02:23, Thomas de Groot a écrit :
>>> Op 07/02/2021 om 04:41 schreef Mike Horvath:
>>>> On 2/5/2021 6:56 AM, Bald Eagle wrote:
>>>>> it's likely not your media - but your media settings.
>>>>>
>>>>> try:
>>>>>
>>>>>
http://news.povray.org/povray.newusers/message/%3C59a9ec1c%40news.povray.org%3E/#%3C59a9ec1c%40news.povray.org%3E

>>>>>
>>>>>
>>>>>
>>>>
>>>> I'm not sure how that applies to my case. I am not using emissive 
>>>> media or the "samples" keyword.
>>>>
>>>
>>> There is nothing really wrong with your code as far as I can tell and 
>>> from own experience. From the outside (of the media) it is even 
>>> rather fast due to the default intervals 1 and samples 1 (Yes! you 
>>> /do/ use samples, even if you don't).
>>>
>>> However, depending on the location of the camera within or without 
>>> the media, render times can be very different; you even may need to 
>>> increase the samples value to avoid splotches, and that will decrease 
>>> render time even more although not that much.
>>>
>>> Using media is time consuming. There is no alternative.
>>>
>>
>> The default for samples is 10.
>> samples default to 1 when using sampling method 1 or 2.
>> The default are, as of version 3.6 :
>>
>> sampling_method 3
>> intervals 1 //DO NOT increase !
>> samples 10
>>
>> Increasing intervals dramatically increase the rendering time without 
>> giving any appreciable improvement.
>>
>> samples 10 intervals 3 render slower than samples 50 intervals 1.
> 
> I don't know where in the wiki there was a line saying defaults being 
> intervals 1 and samples 1,1. Of course, I cannot find that paragraph 
> anymore (typical!); but you are right of course: default samples is 10.
> 
You have a mixup between the old version 3.5 and newer version 3.6 
documentations.

The format : samples 1,1
is that of method 1 and 2. It's used to set the number of samples for 
dark, bright intervals.
It's a leftover from the pre 3.6 version when the default sampling 
method was method 1. It demanded an intervals number large enough to 
match the number of distinct illuminated areas along a tracing path. If 
you had 20 spotlights shining through some media, then, you needed 40, 
or more, intervals : One interval for each illuminated part and one 
interval for each non-illuminated parts between the illuminated ones.

When using the default method 3, when you have two values for samples, 
the second is silently ignored.


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