Render times

[Taz3ds]

Hi all,
I am rendering an interior, might have about 20 spots, sun and sky but the render times to get to 3% noise is about 9 hours for a 2k image.  I am also using dof (corona 9).  It was a few large windows.  At the end of the 9 hours the noise is little but are there things I should be looking for to reduce this time, I can live with 2 hours but not 9 per image. 

Thanks

[romullus]

What is your PC specs? 9 hours for 2K image can be way too long for decent machine, but also can be expected for 10 years old low-spec computer. It also would be helpful to see VFB performance tab while rendering that scene, together with the rendering itself. Also consider using denoiser, depending on the scene and your quality expectations, you can easily cut render times in half, or even more.

[Taz3ds]

Hi, thanks, I hace 64 gb of ram, i9- 7980xe @2.6GHz (not sure how good this is these days)
Rays/sample:142, passes 20.  I can show the render directly as it's  a paid job nda.  I have juat taken off dof, removed all glass and tweaked max samples and max Ray deth to see if that helps

[romullus]

I don't see any red flags in performance tab. Rays/sample is on the high side, maybe because of some complex materials, lighting and/or DOF, but it's not uncommon to have higher rays/sample in interior scenes.

Regarding your PC, you can compare it to others in Corona benchmark: https://corona-renderer.com/benchmark/results but in general it's pretty capable CPU, definitely should be able to render 2K interior in much less than 9 hours.

[Taz3ds]

Thanks for taking a look, I will try to break down the scene.  I was thinking about upgrading my computer and looking at the Threadripper 7980X, I couldn't see that as a bench mark on the link but guessing it will be at least twice as fast as what I currently have

[Taz3ds]

Does anyone tweak max rat depth and max sample intensity?
Also is 6% noise ok, i read 3% is meant for final images

[maru]

First of all, I think it would make sense to update to Corona 11, unless you are in the middle of a project - https://corona-renderer.com/download

Instead of using a specific noise limit, I would suggest the following workflow:
- start rendering your image in a lower resolution like 1920p or even 1280p
- after a few passes (which should not take a lot of time) you should see which areas of your image are the most "challenging" (noise or hard edges are visible)
- set your output to your final resolution
- do a region-rendering of the challenging area that you found in point 2
- observe how many passes you need to get a clean rendering (or "good enough" quality)
- then set that pass limit for the whole image and render it

One other possibility is that there is some issue in your scene. If you would like us to inspect it, feel free to contact us at https://support.chaos.com/hc/en-us/requests/new