Don’t laugh at me - acute baby brain here - but cycles X is part of vorher 3.0 alpha right ?

Yes, it was merged recently.

Ah great !

I wanted tk slowly introduce blender 3.0 to my students

It seems that the UI does change too much anymore till the final release

Trying to understand what Noise Threshold does:

0.1 means what for example?

you set a max / min value and render and wait till the engine decides it is time to stop sampling and denoise

Some more questions:
what happened to adaptive sampling ?
are all areas now again sampled the same way ?

What scenes are you trying to render?

Adaptive Sampling will not give as big a boost in scenes where the noise is fairly even to begin with (which includes many interiors). In addition, if you have a low enough max samples value coupled with a very low threshold value and realistic tonemapping, then it is possible for all areas of some scenes to get sampled evenly (because there was no area that fell below the threshold).

This also takes into account that the way the threshold is calculated now has been improved in Cycles X (which makes it a bit easier for adequate sampling to occur in some scenes). I would also note that you should still take advantage of other noise reducing features such as increasing the minimum light bounces allowed.

Hi ace

In the thread you find a file

The metal under the plastic is very grainy and the Glas refection on the plastic handle reflects more noise too

as said trying to understand how the new system is working and supposed to be used.

Some said compositor denoise will yield better results too.

Adaptive sampling is still in, and it’s activated the moment you check “Noise Threshold” .
Also, threshold 0 means adaptive never kicks in, 1 is lots of noise.
.1 is quite noisy.
I think recommended value for final render is around 0.01, that leaves low residual noise, to be tackled by your denoiser of choice.

To be noted that the UI went through some redesign. This is because the future intended ideal workflow wants to be: “Just choose how much noise you want, and let Cycles do the rest”.
Optionally we can also set a rendertime limit

Where I am confused is then how noise threshold and max min sampling influences each other

The renderer will run for at least “minimum” number of samples if not 0. Then, rendering can stop either by
a) Max samples reached
b) Time Limit, or
c) Noise amount less than threshold
whichever is first (if given and not 0)



So if I set max 10.000 with a noise threshold it will stop rendering at one point not when 10.000 is reached

Due logical - should have realized that earlier.

That is actually - I’m convinced - what is the final plan of developers.
The future workflow where you just set the final quality (threshold) AND/OR a time limit. Never care about anything else. It would be the utlimate goal of the “remove buttons & tweaks” crusade.

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Thats actually the workflow im using with 3.0 im keeping the default 4k samples and 0.01 threshold and i only change the time limit, 10-20sec for simple scene and up to 1min for the complexe one, using a 3060ti

Ah that is super good to know !

This makes it actually super easy for beginners and very easy to teach to students !

Thank you for sharing and confirming !

The latest meeting notes for the rendering team


  • Brecht Van Lommel (Blender)
  • William Leeson (Blender)
  • Kévin Dietrich (Blender)
  • Brian Savery (AMD)
  • Christophe Hery (Facebook)
  • Feng Xie (Facebook)
  • Patrick Mours (NVIDIA)
  • Stefan Werner (Tangent)
  • Michael Jones (Apple)



  • bake transparent shadows for hair is committed and provides a good speed increase. (Brecht)
  • Rendering optimisations were commited for Shadow path compaction and Decouple shadow paths (Brecht)
  • Committed Additive AO (Brecht)
  • Restored render passes Depth denoising No AA on position pass (Brecht)
  • Refactored cycles code organisation
  • Resume work on pause/resume rendering and reducing memory usage (Brecht)
  • Still working on Ray offsetting removal the results look promising but it affect to many things to get it in for 3.0 (William)
  • Sobol Distance scrambling by Mathiue Menuet is committed (William)
  • PMJ distance scrambling is still being worked on (William)
  • HIP integration Work continues on AMD HIP integration. Currently to use this as yet unreleased drivers are needed on both Windows and Linux. Looking into what cards are supported. (Brian)
  • Plan to submit MNEE manifold next event estimation code for 3.1 (Christophe)
  • Working on the Metal Backend first fix kernel side then host side. Hopes to have this ready for 3.1 (Michael)
  • Optix denoising issue caused by driver bug, hopefully fixed for 3.0 (Patrick)
  • Working on patch for animation denoising needs rewrite for EXR (Patrick)
  • Light groups work continues and is near completion (Brecht)
  • Point Cloud rendering primitive almost ready for 3.1 (Brecht)
  • Plan to submit a patch (based off Blender 2.9) for unflattening the vertices for ray intersection (Feng)
  • Metal implementation currently used BVH2 on AMD HW and Metal ART on Apple silicon (Micheal)


Practical Info

This is a weekly video chat meeting for planning and discussion of Blender rendering development. Any contributor (developer, UI/UX designer, writer, …) working on rendering in Blender is welcome to join and add proposed items to the agenda.

For users and other interested parties, we ask to read the meeting notes instead so that the meeting can remain focused.

  • Agenda
  • Google Meet
  • Time: Tuesday 5 to 6 PM Amsterdam Time
  • Next meeting: November 9, 2021

In short…

  • The industry itself is getting more involved (count the corporations lending developers)
  • Cycles in 3.1 looks to be getting some exciting changes and additions (no ray offsetting for scenes of real world scale, MNEE, light groups, point cloud rendering, ect…).
  • It sounds like light groups will still make it into Cycles for version 3.

Also to note, William has just committed the scrambling patch for PMJ. This is perhaps turning out to be the most exciting year for Cycles since its inception.


Can anyone shed light on what this is and what it’s useful for?

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Pretty solid update. We should see more of these as new Cycles is stabilized. One of the (more overlooked) goals of Cycles X was to simplify codebase and make new features easier to implement. The time for it is coming now with Blender 3.0 release.


No news of the texture cache patch ? There was a build available in may, nothing since


can someone explain what ray offsetting is?

When a ray bounces off an object, you have to “offset” the start of the next ray bounce a little bit off the hit point so it doesn’t self intersect.

This is normally done at a very simple level by adding a tiny 0.000001 etc floating point value to the ray start position. For too technical reasons, the coordinate space the 0.0000001 is added in matters.