Difference between Fastest (Optix) and Optix viewport denoisers

What’s the difference between the two? If there is none, what’s the point of having two duplicate entries in one dropdown box?

The tooltip reads: Use the fastest available denoiser for viewport rendering.

Not all computers have an Optix compatible graphics card, so this option will automatically pick the fastest denoiser depending on what’s available.

That honestly makes no sense whatsoever. If Optix compatible graphics card is not detected, then the option should either not be present or should be grayed out so it can’t be picked. This “Fastest” entry is beyond confusing as it implies to a new user that there are 3 different, distinct viewport denoisers. Something as simple as choosing a viewport denoiser should definitely not require a Google search to figure out.

It just doesn’t even make sense in general. If the card is not Optix capable, then the OIDN is not the fastest denoiser you can use, but the only denoiser you can use.


There are 3 options. ODIN, Optix or let the computer choose which one to use. Fastest option is set by default which guarantied that the user has the best option without changing anything. Maybe it could say something like Automatic or something which is clearer to most users.

That still does not make sense.

Since OptiX is GPU accelerated and only supports Maxwell and newer Nvidia GPUs, then it will be pretty much always the case that OptiX will be faster than OIDN.

There may be some obscure case where someone has the bare minimum lowest spec supported Maxwell card in same machine with something like third generation Threadripper CPU, but even in that exotic, unlikely case, I highly doubt Blender actually does some benchmark to properly determine relative performance.

The solution to this UX mishap is simple:

  1. Remove Fastest option and rename OptiX option to OptiX (Faster)
  2. If no Optix capable GPU is present, hide Optix (Faster) option from the list so that only OIDN is available.

As a result, neither camp will be confused. People without OptiX capable GPU will not be left wondering what to use, and people who have OptiX capable GPU will be made aware by the naming that the OptiX is better choice for them.


hi, for me the solution is anable or disable the denois and the sistem decide in automatic which the best solution (if is possible…)

I can rename it to just Automatic and add more detail in the tooltip.

We use separate menu items for automatic choices in Blender. This is by design to avoid data loss when opening files on different computers, and to ensure consistent behavior between the user interface, drivers and API. It may not be that important for a viewport preview setting, but I prefer to be consistent.


EDIT: Ok, I won’t remove the message… but I can see that you already spoke about it, I had the message already written since this morning, and I just pressed send hahaha

I noticed today that it changed, I had a branch built without CUDA or Optix and then I noticed that it was named “Fastest (OpenImageDenoiser)”

I think that when the user see this list:


The user understand that “Fastest(Optix)” it’s like a fast mode of the Optix denoiser, not that Optix is the automatically selected one because it’s the fastest.

Personally my first impression was that “Fastest(Optix)” was not making use of Albedo / Normal inputs to deliver a faster result but with a bit worse qualtiy.

It’s not an important thing, but maybe find some other way of showing that, so it’s not interpreted as some kind of setting of the auto selected denoiser, maybe “Automatic/Fastest” could be better, no need to specify if it’s Optix or OIDN, it’s the faster one, and if you want a specific one you can manually change it.

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My suggestion is that there be only two items: Optix and OpenImageDenoise. If the user has a compatible GPU, automatically choose Optix by default the first time. If there is no Optix GPU compatible, only OpenImageDenoise should appear.
Then in the tooltip explain which is the fastest or slowest, or which one supports more Cycles features.

Anyway I don’t understand API or internal issues. “Automatic” option seems fine to me too.

This seems like the right solution to this.

I’ve seen videos being posted online suggesting there is a fast but lower quality mode for optix, which I think comes from the fact that the option contains the word ‘Optix’. If it was just ‘automatic’, maybe the ‘fastest’ option for the current machine could be presented in the tooltip.

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Yes, pretty much. Automatic will do. Currently, without any external research done by user, the UI suggest there are 2 distinct OptiX modes and one more OIDN mode.

That being said, polluting dropdown boxes with extra option just to preserve scene data between computers is still quite unfortunate way of going about this. Smarter way would be to use OIDN as fallback on machines that don’t have OptiX capability. The UI selection would remain untouched then.

That it makes me wonder if Viewport Denoising (Optix and OIDN) are or are not using Albedo/Normal inputs.

Viewport denoising is using albedo and normal inputs.


I also agree that either the naming needs to be more explicit or we just have to get rid of this “Fastest” option, currently it’s very misleading and makes you think that there are 3 different options: hell, the first time I saw it I even thought it was a bug! :sweat_smile:

What about having an “Automatic” checkbox that fully disables the dropdown UI for the viewport denoiser?
The problem with that option is that it “fights” in UI/UX with the render denoiser options, so I don’t quite like that.

Anyways, for me an Automatic options in the dropdown is more than enough IMHO.

Regarding using Optix and OIDN as fallback, I prefer to have the option, I have an architect that likes how OIDN works in the viewport way more than Optix, it’s just a personal preference, I personally prefer to have choices and not being forced into the computer picking things :slight_smile:

If you don’t have OptiX capable GPU in your computer then you have no option. The fallback does not mean lack of option. It means that if someone without OptiX capable GPU opens scene from someone else who has selected OptiX denoiser, then the scene will render using OIDN denoiser instead of without denoiser at all. But if you are the creator of that scene, and you DO have OptiX capable GPU, but select to use OIDN instead, then it would always render using that. You would not be forced to use OptiX just because you have OptiX capable GPU.

What I understood was to eliminate the options and just leave the Enable Viewport denoise option and let it to select the system.

If there is no option removal, then it’s just the Automatic behavior I think :slight_smile:

Yeah I was confused as well. It appears to someone looking at the UI as if theres a 2nd optix denoiser which is faster than the other

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Can is ask if Optix in the settings is the same Optix available in the denoiser section?
Im getting confused as someone is stating they are 2 separate things