[Bf-cycles] Base 'Render' samples (simple request)
jrdnmlr at gmail.com
Sun Nov 13 02:02:43 CET 2011
I've added more details here:
On Nov 11, 2011, at 6:36 PM, Jordan Miller wrote:
> It's not impossible at all and I've just done the analysis (takes less than 1 second of analysis for any image, and as I've shown it only needs to be computed for waaaaay less than 1% of the time during a render). I guess what I'm saying is NOT "noise" per se. Rather, the rate of change of pixel RGB values over time. Whether the renderer or compositor is making a "noisy" image on purpose due to complex textures, the fundamental measurement, since we have an iterative function, is the rate of change of the pixel value.
> Here are the files:
> For example, one needs only to do a boolean subtract of one render from a previous render, convert to B&W, then analyze the histogram. As you can see from the attached files (.blend and analysis), this will ALWAYS follow a very predictable pattern.
> Note also that these "booleaned" pixels actually can tell you where you should be sampling more, as these areas are going to be changing the fastest.
> Hope that makes sense...
> Anyway, you can see where the "noise" or the "undersampled" areas are very very easily. Look at the attached file "MeasuringNoise_008pass-004pass.png" to see what I mean. This has the 4 sample pass image boolean subtracted from the 8 sample pass image then converted to B&W.
> shouldn't this be VERY easy to make a part of the render? Maybe as an "Advanced option"?
> Something like "Continue rendering until fewer than 10 pixels have a noise value under 64" as a default advanced setting.
> Again, this will DRAMATICALLY decrease rending time for animations because you continue rendering until you hit your sampling threshold, not based on a constant number of render passes.
> On Nov 11, 2011, at 5:24 PM, storm wrote:
>> В Пт., 11/11/2011 в 14:18 -0500, Jordan Miller пишет:
>>> couldn't the compositer or the cycles engine measure the noise
>>> reduction with each successive pass and thereby achieve a user defined
>>> noise threshold? it would allow standardization of all renderings
>>> (rendered to a noise level of ## dB across >90% of the image)...
>> Unfortunately it impossible. You only can guess variance decay using
>> 1/(sqrt(N)) with N = number of passes. Any statistically based
>> measurements far from what we see by eyes. Maybe complex psy-based
>> algorithm exist, but i doubt it can utilise fact that only portion of
>> moving picture take more attention then other. Random generators not
>> perfect, there always be some parts of image that too noisy and stay
>> noisy in next frame, so you get false positive.
>>> as people start to use cycles for animations choosing a pass value
>>> high enough for complex frames may oversample simpler frames and
>>> unnecessarily increase render time. having the end user figure out
>>> which individual frame will have the most noise is also non-trivial.
>>> being able to simply set a "noise level" IMHO would be cleaner
>>> interface and technically more accurate for what the end user is
>>> trying to achieve, while also being scalable to animations and any
>>> desired rendering or compositing complexity.
>>> On Nov 11, 2011, at 2:04 PM, Brecht Van Lommel
>>> <brechtvanlommel at pandora.be> wrote:
>>>> I don't think this is needed, there is no right value anyway, it
>>>> depends on the scene. I'd rather have a low value that can be
>>>> increased later. There's currently no way to render something without
>>>> understanding that this value needs to be tweaked anyway.
>>>> On Thu, Nov 10, 2011 at 6:59 PM, David Black <db4tech at yahoo.co.uk> wrote:
>>>>> Hi Brecht,
>>>>> How do you feel about changing the base 'Render' samples from 10 to 1000 (or
>>>>> 500 at the very least)?
>>>>> Thought it might save complaints and help new users, who don't understand
>>>>> why their new Cycles renders are noisy.
>>>>> Thank you kindly for all your hard work, very much appreciated,
>>>>> my degree work would not have been possible (using Blender) without it!
>>>>> Bf-cycles mailing list
>>>>> Bf-cycles at blender.org
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