Persistent noise problems...

[daniel.reutersward]

Hi,

I´m having some trouble both in a commercial project and in a personal project.
The problem is serious persistent noise that won´t go away.

This is a problem in both projects and something I have had problems with more and more with each new version of Corona.

Both scenes are lit with HDRI´s from cg-source.

I´ve tried the following things without any luck:

- Resetting Corona settings to default
- Merge everything to a new clean and empty scene
- Made sure Bitmap Proxies/Paging is disabled
- Removed everything except walls, floor, ceiling and windows
- Removed all bitmaps for diffuse, refl. gloss, and bump
- Made sure the window glass uses the "Thin (no refraction)" option

I´m using 2x Xeon 2697 V3 and still the speed feels way worse than with Alpha 6/7 and my old i7 6-core.

I´ve attached a few images to demonstrate what kind of noise I´m talking about and one image of the albedo value for one of the scenes.

Any help would be very appreciated!

(I can of course send over my scene, just need little hint on how to and where)

/Daniel

[johan belmans]

Hi Daniel

what rendersettings did you use?

[daniel.reutersward]

First I used default settings then I tried raising GI/AA to 32 and when that didn´t help I tried raising it to 64 without any difference in noise.

[johan belmans]

May I presume you used PT + UHD cache?
Add (Render elements) all the Cessential render passes, so you can check if the problem is in direct lightning or indirect ligtning.

Is there a bump map on the walls?

[maru]

Are you using portals in this scene?
https://coronarenderer.freshdesk.com/support/solutions/articles/5000501660

[daniel.reutersward]

Yes, I used PT + UHD Cache.

There was a bump map on the walls, but in the images (as I wrote in my first post) I removed bump, diffuse and refl. gloss to see if any of those maps caused the problems.

I´ve attached the direct and indirect passes, you can still see small noise.

I´m not using portals. I tried with portals and the render times went up about 3x without removing the noise. When I tried with portals I followed that guide.

[maru]

Can you see if it's still noisy if you disable reflectivity for the floor?

[daniel.reutersward]

I removed the reflectivity for the floor and the noise is still there..

[Ondra]

the noise is caused by the direct light from environment. ARe you sure that:
1) there is no backplate/enviro geometry object outside?
2) there are no lights in windows
3) glass in windows, if present, is set to "no refraction"?

Also what do you use for lighting? HDRI, sky, constant color? If you try it with constant color, you should definitely see an improvement in "portals vs. no portals". You can try that for the sake of debugging

[daniel.reutersward]

I double checked and there are no lights in the windows and the glass in the windows is set to "no refraction".

The scene is lit with an HDRI and there´s a grey plane outside to bounce light back in to the interior.

I tried with a CoronaColor in the environment slot, without the grey plane outside, I not sure if that´s what you mean with constant color or if I misunderstood?
However the noise is still there..

[Ondra]

there´s a grey plane outside to bounce light back in to the interior.

[daniel.reutersward]

I´ve used that before without these problems... :)

I didn´t think it was wrong having a plane outside to simulate some kind of ground for the outside?
What would be the correct way to use HDRI and get rid of the black bottom for Corona? Create another half in PS?


Update: However, I still have the persistent noise WITHOUT the plane?

I tried with a CoronaColor in the environment slot, without the grey plane outside

[Ondra]

ok, using the plane for ground is actually not that bad, I thought you had it placed vertically. Although still, painting the bottom of the HDRI in photoshop would be faster ;)

[maru]

Any chance you can upload the scene or a similar one with this problem? Maybe this will be a faster solution. :)

[johan belmans]

oeps, I missed the bump message in your first post.

Just to rule out the materials as the problem, you could render it with eveything as a white material.

Although CG source has excellent HDRI's, try using another HDRI.

Another thing you could try is optimizing your # of passes by switching to bucket mode and render only a problematic spot with region render.
Make sure you put the amount of passes on 1 and play with the "Samples per iter". Whenever you are statisfied (read less noise) use this amount in progressive mode as your amount of samples.
With this workflow you can change the values of GI/AA and Light samples Multiplier aswell to see some quick results.

[PROH]

Hi. Regarding HDRI. Some of the best I've found so far is from HDRI-Sets. Link: http://www.hdr-sets.com/index.php/free-sets.html

They have some free sets to try out, complete with back plates. I especially like the two outdoor sets. They give nice sharp shadows and lit the scene without the typical "to bluish" color tone.

Try it out.

[daniel.reutersward]

ok, using the plane for ground is actually not that bad, I thought you had it placed vertically. Although still, painting the bottom of the HDRI in photoshop would be faster ;)

I should have written that I used it as a ground plane :) Will try painting the bottom of the HDRI and see if that makes any difference. However the noise was still there with CoronaColor as a light source.

Any chance you can upload the scene or a similar one with this problem? Maybe this will be a faster solution. :)

I´ve never uploaded a scene. But I can remove some commercial textures and upload the scene. Where should I do that?

oeps, I missed the bump message in your first post.

Just to rule out the materials as the problem, you could render it with eveything as a white material.

Although CG source has excellent HDRI's, try using another HDRI.

Another thing you could try is optimizing your # of passes by switching to bucket mode and render only a problematic spot with region render.
Make sure you put the amount of passes on 1 and play with the "Samples per iter". Whenever you are statisfied (read less noise) use this amount in progressive mode as your amount of samples.
With this workflow you can change the values of GI/AA and Light samples Multiplier aswell to see some quick results.

Since I tried with CoronaColor and still got the persisten noise I don´t think it´s the HDRI´s fault.
I will try render using only a white material and also try with bucket mode.

Hi. Regarding HDRI. Some of the best I've found so far is from HDRI-Sets. Link: http://www.hdr-sets.com/index.php/free-sets.html

They have some free sets to try out, complete with back plates. I especially like the two outdoor sets. They give nice sharp shadows and lit the scene without the typical "to bluish" color tone.

Try it out.

I´ve never had any problem with the HDRI´s from Cg-source. I think the quality is good but I will check those out!

[maru]

I´ve never uploaded a scene. But I can remove some commercial textures and upload the scene. Where should I do that?

For example here:
https://corona-renderer.com/upload/
Or even better, you can create a new support ticket and attach the scene:
https://coronarenderer.freshdesk.com/support/tickets/new
It would be best if you could make it as small as possible. It can look completely different only that the noise problem is still there.

[aurelarchi]

Same problem here.

So i tested with and without HDRI for lighting, and i have less noise with a sun+sky system than a HDRI one..........
Hope it can help you.

[daniel.reutersward]

I´ve never uploaded a scene. But I can remove some commercial textures and upload the scene. Where should I do that?

For example here:
https://corona-renderer.com/upload/
Or even better, you can create a new support ticket and attach the scene:
https://coronarenderer.freshdesk.com/support/tickets/new
It would be best if you could make it as small as possible. It can look completely different only that the noise problem is still there.

Thanks, I will do that! In the meantime I get a little less noise with portals and very high GI/AA settings, takes a long time to render but it gives me an acceptable result, good enough to finish the project :)

Same problem here.

So i tested with and without HDRI for lighting, and i have less noise with a sun+sky system than a HDRI one..........
Hope it can help you.

I noticed that too in a previous project, but for this project I really liked the lighting I got with the HDRI so :)