[Mihai]

Lets use this thread to post discussions and tests for NR to keep things tidy

Please read the manual page, it has some important info:
http://support.nextlimit.com/display/maxwell4/Denoiser

After some testing and also playing around with the Altus standalone, I would prefer the following changes to UI:

1. Removing the "Denoised image" input. It's awkward having to specify the regular image output and type in the Output section, but denoised image and type in another place. I'd prefer if it automatically created an output image with the _denoised suffix, in the format already specified in the Output settings.
2. There is a command line input for (I assume) controlling the Altus NR but none of its arguments are taken into account for now it seems. I would especially like to control the Radius parameter in Altus which has a huge influence on the NR. Please add at least this Radius parameter to the UI.
3. I don't see the need to have both a "Auto config" checkbox, and a preset dropdown. The default "state" of settings is already the autoconfigure. As long as you don't touch any of the settings or input any cmd line settings. So I would prefer, right after the enable NR, simply have a dropdown labeled Preset.
4. The names of the presets is a bit misleading because adding the shadow channel will for many renders make no difference. In fact also the normals channel and reflectance channels will matter very little if your materials are smooth and don't have high frequency textures. The way it works is that in case your material has bump or normals and a detailed texture, lets say a wood or a cloth, having normals and reflectance channels on makes sense - Altus will use the "clean" info in these channels to determine what is good detail and what is noise.
   
   But for many renders where you have mostly shiny, clean materials, these channels are redundant and add considerably to the render time - especially the shadow channel. Since any presets have to do with what type of materials you have in your scene, I would like to rename them to something like: Smooth materials / Detailed textures w/ bump. (at least to give a hint when user should choose one or the other)
5. The "Use GPU" checkbox should be renamed to Use CPU and unchecked, and put towards the bottom, right above the Command Line, because almost everyone will use GPU, it's like the default. Personally I would not ever use CPU, so I wouldn't have any checkbox at all in the UI, just keep it as a command line option. So it's a very low usage option, if it's going to be visible at all, have it towards the bottom and name it as the exception rather than a checked default.

So I imagine the UI could look like this:

NR_UI.png

The Preset dropdown affects:
- which channels are activated
- sets a default Radius value.
- sets denoise shadow to off
- sets use cpu to off

Any change to the parameters and the Preset dropdown changes to Custom.

In "Smooth materials" preset, only the Position channel is activated.
In "Detailed materials" preset, all channels are activated.

Perhaps a third intermediate preset should be added, which enables all channels except shadow.

I realize the Maxwell team wanted to make this NR as simple as possible and that's a good thing to keep in mind but in this case it sacrifices too much flexibility and above all, we end up with renders 2-3x slower....that's a big deal. I think sometimes we overestimate how fearful users are of parameters. If it means more than twice slower render...give me some control.

Please let me know what you think

[Mihai]

When doing a network rendering, no shadow pass is rendered when NR is set to Accurate. Bug?

[luis.hijarrubia]

Adding normals or reflectance to a render is almost nothing in render time. The only that really affect is Shadow pass. So I wouldn't add more modes based on so little time benefit.

[alberto.manchenos]

Hello Mihai,

Thank for your comments. I found them very interesting and I would like more forum users give their opinions about this topic.

Related with suggested changes:

1. Removing denoised image input. I basically agree. We didnt do it this time, because we had no time to coordinate with all plugin devs, when this improvement was reported. But its something we want to change in near future, to avoid the need of rewriting paths. In the meanwhile, its possible to drag and drop the path from another text box (In maxwell render, not studio), and the '_denoised' suffix is set automatically. (This has to be fixed also)

2. Indeed, radius parameter, should appear at least in command line options. The command line below denoiser options is general, not denoiser specific.

3. If I understand you right, the change would say to collapse the autoconfigure check and its dropdown, in only one dropdown with three possible values: the current no auto-config; Fast, and Accurate (with possible name changing) isnt it?

4. Apart from Shadow channel, rest of channels does not affect much to render time, as Luis says in another post. We have the distinction Fast/Accurate to avoid the usage of shadows channel indeed.

5. Switch the 'Use GPU' checked to 'Use CPU' unchecked, could make sense, but I dont find it particularly annoying. I think this option visibility is important because some people could prefer to use CPU denoising. (As a Microsoft Surface where i have seen Maxwell being tested )

When doing a network rendering, no shadow pass is rendered when NR is set to Accurate. Bug?

Its not a bug, its a feature! JK... (Indeed it should to get their settings from scene. It will be fixed)

[Mihai]

Hi Alberto,

If you say the other three channels add very little to render time, then delete the whole "Channels" section from my suggestion and just keep the "Preset" dropdown with options: Fast/Accurate/Custom (it auto switches to custom as soon as we change Radius, Use GPU, add a cmd line param).

I also think the default should be to apply denoise at the end. So defaults would then be:

Fast (no Shadow channel)

Radius 3 (from playing with the Altus standalone from their site, I get less burry results while still getting good NR)

Apply denoise: at end

Use GPU

Denoise shadow: off

I haven't tried yet what happens if I have shadow on in NR, and I also have shadow on in render channels. Is that the same as if Maxwell needs to render 3 renders at the same time?

Besides adding the radius parameter, please make the cmd line working so I can write different settings there from Altus. It seems there are cases where we really need to tweak some things. I have noticed especially in reflections (where the reflectance/position channels won't help), they get weaker and less detailed. A very good and simple example of what I mean is here, rendered by ChristianZ:

viewtopic.php?f=140&t=44808&start=15#p394539

It would be great if you could show that to the Altus devs, because in that case I would get much better result just using PS noise reduction. Maybe they have some tips on which settings to use to avoid reflections getting so blurry.

[seghier]

Hello
If it's possible : can the denoiser have feature like extra sampling ? To denoise specific objects / materials
For example if the background is clean we don't need denoise it

[luis.hijarrubia]

I haven't tried yet what happens if I have shadow on in NR, and I also have shadow on in render channels. Is that the same as if Maxwell needs to render 3 renders at the same time?

The 2 renders for denoiser are rendered sequentially, not at the same time. Adding shadow channel is that on them both, so you have 2 renders with shadow channel. A render with shadow channel is about x1.5 times a normal render, so 2x with shadow it's like 3x a normal simple render, if that's what you meant.

[jc4d]

Hello
If it's possible : can the denoiser have feature like extra sampling ? To denoise specific objects / materials
For example if the background is clean we don't need denoise it

+1 to this idea.

[chedda]

I'm a bit disappointed this even exists to be honest. There are plenty of after market noise reduction plugins already existing. Playing with the slider on the features page shows wood grain just disappearing into a bland mess. This is bloatware at best a non feature.

[Forum Moderator]

I'm a bit disappointed this even exists to be honest. There are plenty of after market noise reduction plugins already existing. Playing with the slider on the features page shows wood grain just disappearing into a bland mess. This is bloatware at best a non feature.

Hi Chedda,
One of the things I like from the implementation is that depending on your quality criteria, you can leave the render more time and the denoised result will improve. The longer you leave the render running, the closer the denoised version will look to the not-denoised version; the denoised version converges to the not-denoised one with time, but in between, you will get valid images. Actually, you could always launch the renders with Denoiser as you will get both versions: denoised and not denoised, so you basically have an additional denoised version that could be useful, or maybe not, but it's available in case it is.
Also, in the end, you can play with masks to mix denoised and not-denoised renders in an image editor. There are some cases where the Denoiser does not save much time, but in others, you can save many, many hours.
Fernando

[sinatropus]

Hello
If it's possible : can the denoiser have feature like extra sampling ? To denoise specific objects / materials
For example if the background is clean we don't need denoise it

The whole point of extra sampling is to remove noise, so in that sense that makes all the sense. On the other hand, how long does the NR take compared to the render pass? Would that make a difference? I'm still on the fence regarding v4 so can't try for myself.

And the most important question, does it really deliver the advertised 2-8x speed gain?

[luis.hijarrubia]

The whole point of extra sampling is to remove noise, so in that sense that makes all the sense. On the other hand, how long does the NR take compared to the render pass? Would that make a difference? I'm still on the fence regarding v4 so can't try for myself.

And the most important question, does it really deliver the advertised 2-8x speed gain?

As I see it, having something like custom alpha for NR it's a post-process compositing tool. I find it very useful, but it's something you can do with denoised and not denoised image on photoshop, blend both images like you want. As for time, NR it's just a few seconds in it's worst case, non comparable with another render pass.

[chedda]

If i wanted a fast clear render i wouldn't be using Maxwell Post work or any interference with an image is unacceptable to me but i guess i'm weird.

[seghier]

The whole point of extra sampling is to remove noise, so in that sense that makes all the sense. On the other hand, how long does the NR take compared to the render pass? Would that make a difference? I'm still on the fence regarding v4 so can't try for myself.

And the most important question, does it really deliver the advertised 2-8x speed gain?

As I see it, having something like custom alpha for NR it's a post-process compositing tool. I find it very useful, but it's something you can do with denoised and not denoised image on photoshop, blend both images like you want. As for time, NR it's just a few seconds in it's worst case, non comparable with another render pass.

Ok for images
And animations ?

[luis.hijarrubia]

If i wanted a fast clear render i wouldn't be using Maxwell Post work or any interference with an image is unacceptable to me but i guess i'm weird.

The thing is that you can have both. And if you know how to use it it's almost free. For example you are leaving the pc overnight to have an image with SL 20. You can leave it with denoiser to SL 19 (2 renders SL 19 are like SL 20,5 aprox) and denoiser at the end. It will take like 5-10 seconds to do the denoiser. And the next day you have the normal render and a denoised image, just in case some dark places in the images still have noise.

For me, it can be very nice in the work pipeline. You can have previous version of some WIP and the denoiser can help to make the scene up with low SL renders. And you can always have that option just in case a deadline crash on you. You will have a not noisy image on every step of the WIP.

Nothing changes on maxwell render quality. We just add an option that can help on certain situations.