[ MANTRA ] Strange striped noise in render

[toothpaste]

 

I'm getting thick striped noise patterns in my renders in mantra and I am at a loss as to why!

 

This is what it looks like:

 

This is in a clean scene rendering with even higher samples, you can still clearly see the striped noise pattern:

 

I've included the test scene here:

noisyCircle.hiplc

 

Please let me know why this is happening so I can get some sleep!

Thank you!

[TobyGaines]

First thing I think is - why would there be so much noise in such a large, flat area, where there's no apparent objects to cast shadows or require other kinds of samples - ? I'd look into not creating the noise in the first place, see if there's anything that can be turned off. You'll save on the render time that created the noise as well as the time it would take to clean it up.

Got the scene open now, and your geometry is self-shadowing, and I can't tell why - maybe the size of your scene. Creating my own circle & env light doesn't do that. Fix that, and then the noise isn't created. Turning on Backface Removal fixes it, or turn off self-shadow,, or turn off shadows in the light if you don't need it, etc. 

( for future reference, 6 samples isn't very high ; 7-9 samples is medium quality )

[TobyGaines]

Raytracing Bias is another setting you can use to fit the rendering to your scene scale ( increase it, in this case ).

My guess is that the pattern is from optimizations that most renderers use, it's only visible because the large flat area exposes it

Edited October 18, 2020 by TobyGaines

[toothpaste]

Thanks for your help TobyGaines!  I've followed your advice and achieved much cleaner renders!