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ManteDec

To much noise and rendertime

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Hey, iam using a simple glass material with some tweaked parameters and i rendered out one single frame, it took me 1.5 hours to render it complety and i still got a decent amount of noise?

Im using a hdri image for lightning and increased my samples from my lightsources to reduce noise. anyone would know how to reduce my noise?

This are my render settings.

 

fluids.mantra2.0118.png

fluids.mantra2.0122.png

Screenshot_4.jpg

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First you should try to reduce your noise level : I see you increased it (maybe to get shorter render time ?), but its default value is 0.01, and it has a direct impact on noise as it a threshold to trigger more samples when it detect too much variance in the the samples already sent. By increasing it, you basically tell Mantra to stay to its minimum samples when he sees lots of variations into adjacent samples, leading to a bad estimation of the color/intensity of the pixel, and then allowing adjacent pixels to get very different results from one another. So you should decrease it.

Then maybe you should also render a pass with the number of samples sent by pixels, to have an idea of what is happening during rendering.

You could also render different passes, to see from where this noise is mainly coming : from diffuse, or from blurry reflections ? Then only focus on / increase the appropriate parameters of quality (diffuse, reflection, refraction, sss...), instead of "global". These are all multipliers of your initial pixel samples (in your example you have 225 samples per pixel globally).

So increase the ones you really need, to cut your render time while keeping low noise.

Last but not least, increase the max Ray samples (9 in your example) : it is nice to increase the quality of the appropriate samples (diffuse, refl, refr etc.), but if the global limit of the max ray samples is still 9, then is does not have any effect because it is a global limit.

Edited by StepbyStepVFX
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1 hour ago, StepbyStepVFX said:

First you should try to reduce your noise level : I see you increased it (maybe to get shorter render time ?), but its default value is 0.01, and it has a direct impact on noise as it a threshold to trigger more samples when it detect too much variance in the the samples already sent. By increasing it, you basically tell Mantra to stay to its minimum samples when he sees lots of variations into adjacent samples, leading to a bad estimation of the color/intensity of the pixel, and then allowing adjacent pixels to get very different results from one another. So you should decrease it.

Then maybe you should also render a pass with the number of samples sent by pixels, to have an idea of what is happening during rendering.

You could also render different passes, to see from where this noise is mainly coming : from diffuse, or from blurry reflections ? Then only focus on / increase the appropriate parameters of quality (diffuse, reflection, refraction, sss...), instead of "global". These are all multipliers of your initial pixel samples (in your example you have 225 samples per pixel globally).

So increase the ones you really need, to cut your render time while keeping low noise.

Last but not least, increase the max Ray samples (9 in your example) : it is nice to increase the quality of the appropriate samples (diffuse, refl, refr etc.), but if the global limit of the max ray samples is still 9, then is does not have any effect because it is a global limit.

Thanks i will try if thanks for the good explanation 

Edited by ManteDec

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This could be the known issue with using the GGX brdf, you could render for 6hrs and still have noise. If the noise is in the Refraction channel, switch the brdf to Phong, and it should clean up nicely - and hope Sidefx fixes it soon

We discussed it here ;

 

 

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Almost all the noise will be coming from indirect rays, so there's a few things we can do. Can you PM me a link to a zipped up scene with everything needed for the frame you've shown here?

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