Cycles and noise in final renders

I’m getting noise in some of my cycles renders…not too sure why. I’ve read the page that talks about how noise gets created, but I don’t see in that page anything I can use to kill the noise…

any suggestions?

Can you share an image or the blend file? There’s different ways to get noise reduction but they depend heavily on the scene.

Yeah I get that a lot too, which is why I don’t like or use cycles. The same thing happens when I use environment lighting.

certainly…file attached…

http://www.coffeeonmars.com/screenshots/lotsa-noise.blend

well that’s lousy…I have gotten some very nice cycles renders. I don’t see the rhyme or reason between noise or no noise.

Ok, I just looked at the scene and these are the things that comes to my mind (I hope it helps):

  • First and most important!! If there’s glass or glossy materials you need a higher samples count, 128 is just not enough. A good starting point is 500 samples (not square samples!).
  • Enable Multiple Importance in the Settings of the World tab, “map resolution” should be the width of your render.
  • Use Area lamps instead of meshes with emission material. (And check Multiple Importance on the lamp settings too).
  • This is not always the case but sometimes it helps to have some world illumination, depending on just one light can cause a lot of fireflies.
  • Mix the glass shader with a transparent shader, using the light path node (is shadow ray) as the factor, that way you get transparent shadows for the glass objects.
  • Deactivate Reflective caustics and Refractive caustics in the light path settings if you don’t need caustics.
  • Use the clamp options to reduce fireflies and noise, it reduces the brightness of the glass so try to use low values.

There’s also other things that can help to reduce noise, but as I said before it depends a lot on the specific scene. Some of the things I said may not be optimal for other scenes, so if anybody else knows some other tricks please let us know :slight_smile:

Multiple Importance in the world tab will do nothing without environment lighting via HRDI or LDRI. And it shouldn’t be set to the width of your render, it should be set to the width of your environment image.

And never clamp direct lighting, it will kill the dynamic range of your render.

Consider switching to branched path tracing. It will allow you to tweak samples so that only problematic materials get more samples.

In the case of the shared scene branched path tracing doesn’t do much, it looks almost the same. Also, even if the enviroment is not using an HDR image having multiple importance checked helps to reduce the noise.

Again, it heavily depends on each scene.

Moved from “General Forums > Blender and CG Discussions” to “Support > Lighting and Rendering”

From memory, using area lights are more efficient at lighting then emission planes?

Testing at 100% res with 1000 samples, looks clean. While some optimisations may help, 128 samples usually isn’t enough for most scenes. Took me 2:46s to render on CPU

Thank you…just making a few of the suggestions made a huge difference. More than one person has said that tweaking Cycles renders are scene-specific…so, just how does one arrive at the scene-specific tweaking needs?

I’d recommend you to watch a lot of tutorials about cycles, to get a better understanding of how it works; BlenderGuru and BlenderCookie have very good tutorials on the subject. The cycles threads on the forum are also a good place to search for information.

And of course, experience by yourself, that’s really the best way to learn.

word…thank you!


  • Could enable most passes on render layers to see which ones cause the noise on each area
  • Could determine some of it too, like here where there is a diffuse material and light is blocked by an object so it’s probably diffuse indirect pass that has the most noise. Diffuse indirect render pass agrees. Since world gives some light already, might be able to get rid of indirect diffuse altogether by setting its bounces to 0 (direct light only).
  • Transmission is also noisy. Glossy has some too (not shown). There are completely black areas which could indicate that there aren’t enough bounces for transmission, or it could come from overlapping geometry which doesn’t play well with glass.
  • White areas have values over 2, where visible range stops at 1. Means that either those are going to be blown out, have to level adjust after rendering, or need to tone down light strengths.