Am 24.07.2014 09:37, schrieb scott:
>> The second image shows virtually the same scene, but with radiosity
>> caching disabled, the radiosity count parameter set to a much lower
>> value, and rendered with UberPOV's oversampling ("anti-aliasing") mode 3
>> with settings chosen to render in about the same time; speed was 3076
>> pps in this case. Oversampling was set to +am3 +a0.056 +ac0.9.
>
> Looks very good. What is the keyword needed to disable radiosity caching
> and what does the +ac value mean?

To disable caching, just add the keyword "no_cache" to the radiosity 
block. Make sure to not set the "count" parameter too high - a value as 
low as 10 is perfectly ok for this approach.

As for the mode 3 oversampling, this mode is driven by a stochastic 
algorithm, similar to focal blur; the +a parameter specifies the 
/variance/, and the +ac parameter specifies the /confidence/.

In layman's terms, the mode 3 is all about estimates: While it renders 
pixels over and over again, it estimates (A) the colour of the pixel, 
(B) the error in the estimated colour, i.e. how much it still differs 
from the actual value, and (C) the reliability of the error estimate. 
The +a parameter specifies the maximum estimated error you are willing 
to accept, while the +ac parameter specifies the minimum reliability you 
demand for that error estimate.

In even simpler terms, the +a parameter affects the amount of general 
noise in the resulting image, while the +ac parameter affects the amount 
of speckle artifacts.

(Last not least, the +r parameter puts a hard maximum on the number of 
samples per pixel. The effective limit is 4 to the power of the 
parameter value, making it approximately the same as for a worst-case 
scenario in anti-aliasing mode 2.)

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