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Hello and noisy render question

Unread postby RFraser » Sun Jan 26, 2020 3:09 pm

Hello fellow Clarisse users.

I am a noob! user and am still very much feeling my about in the dark. Some methodologies mate perfect sense and some I find hard to grasp!

I am struggling to achieve a decent high quality render. In the attached images I am getting a lot of noise and grain especially in the VDB clouds.

The cloud VDB's are from the public Disney dataset so should be of a hi quality and other renders I have seen using them show no noise.
The scene is lit by a 16k HDRI environmap.
The scene has a very thin box volume set to 0.0005 with a volume shader set to 0.01.
The scene is rendered at 1080p with quality set to "Full Resolution".
Otherwise the Path Tracer and Image are left at it's default values.

What settings would you recommend to improve the render quality and remove the noise from the clouds?

(Buildings from KitBash3dand HDRI environment map from HDRI Haven)
Attachments
City_04.jpg
City_03.jpg
City_02.jpg
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Re: Hello and noisy render question

Unread postby dboude » Mon Jan 27, 2020 9:46 am

Hi,

I recommend those videos :

https://www.youtube.com/watch?v=0jWplKiJKjA

https://www.youtube.com/watch?v=Reco31CdT1g

Welcome to the community

Cheers ;)
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Re: Hello and noisy render question

Unread postby mdkai » Mon Jan 27, 2020 11:52 am

On a side note
First a highres HDRI is not guarenteed offering a better quality for the lighting or sampling, rather the opposite, as its more difficult to sample bright parts while consuming more memory. Environment lights have their own sampling value to detect the brighter areas (sampling resolution)
It's good for accurate reflections or in camera background.
You can improve it by using a preblurred version, like with a lensblur filter, convolute or spherical harmonic based method.
These preserve the bright areas much better.

Second, volumes and SSS are causing noise to happen in 3 dimensions which makes them quite demanding for higher samples. Rule of thumb is: To half the noise means 6 times more sampling in that specific area (volume) or else you oversample the entire image !
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Re: Hello and noisy render question

Unread postby Akam » Mon Jan 27, 2020 2:14 pm

Hello :)
If you have a nvidia gpu you can also enable optix denoiser. For that select your layer and go to the Filters tab. There you can add opitx denoiser.
Works good for single images, not sure about animation. But as I remember correctly it should only be used with still image not animation.
If you render only single images and don't care much about optimal rendertime try AA something like 32 and material sample between 64-128, also for distant light and environemt. Additionally you can raise the Volume sampling multiplier, but be carefull with that multipliers, they work as multipliers for the Material Sample Count(msc). So if you have 64 msc and multiplier for volumes on 10 you get 1280 samples for volumes ;)
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Re: Hello and noisy render question

Unread postby RFraser » Mon Jan 27, 2020 8:57 pm

Thanks for the replies guys.

The sampling advice in the videos certainly helped although I think I may have gone a bit too far, it's been rendering over 6 hours now and although greatly improved there is still quite a lot of noise.

I think the main culprit is the HDRI (16K) since I see FAR less noise with a simple directional light.
Next I will try a smaller one to see if that is an improvement on both noise and render times).
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Re: Hello and noisy render question

Unread postby isoyann2 » Mon Jan 27, 2020 10:42 pm

For the clouds, using a specific lightset, you can use 2 distant lights : a blue one with a 180 degres spread, matching the blue cast of the HDR, and a warm one mathing the sun. A little more work for you, a lot less for the renderer.

Cheers!
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Re: Hello and noisy render question

Unread postby RFraser » Tue Jan 28, 2020 9:29 am

Once again thank you for your patience.
@isoyann2, yes that's a good idea, I already tried with ! light but two will be much closer to the HDRI. I will try this next.

My latest renders are still a little noisy but much better. They have been saved with odd vertical bands "water mark". I have saved them as both PLE and non-PLE and they both have the same vertical bands in the render. The bands are not visible on the screen before saving. Any idea what the cause is and a solution?

Thanks

City_06.jpg
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Re: Hello and noisy render question

Unread postby dboude » Tue Jan 28, 2020 9:35 am

Hi,

Weird ! Which version are you using ? Which format do you use to write the image to disk ?

Cheers
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Re: Hello and noisy render question

Unread postby RFraser » Tue Jan 28, 2020 12:12 pm

It's the latest version (4.0 sp5 PLE).
Saves as a 8bit Tif (which showed the lines) and uploaded as a minimal compression jpg.
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Re: Hello and noisy render question

Unread postby dboude » Tue Jan 28, 2020 12:24 pm

Could you confirm that the stripes don't appear when using another file format (when writing) please ?

Thanks
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