every new render produces different result

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Albertep
Posts: 3
Joined: Mon Feb 06, 2023 7:42 pm

every new render produces different result

Post by Albertep » Mon Feb 06, 2023 8:02 pm

The one image is rendered immediately after the other. All settings remain the same, i didn't even close the render window. All i did was hitting the render button again.
What causes this and how can i get consistent results?
tw42-houtwerk4-breedpaneel-uitgebreid_detail4high3b.jpg
tw42-houtwerk4-breedpaneel-uitgebreid_detail4high3b.jpg (136.44 KiB) Viewed 2375 times
tw42-houtwerk4-breedpaneel-uitgebreid_detail4high3a.jpg
tw42-houtwerk4-breedpaneel-uitgebreid_detail4high3a.jpg (139.07 KiB) Viewed 2375 times

Fletch
Posts: 12897
Joined: Fri Mar 20, 2009 2:41 pm
OS: PC 64bit
SketchUp: 2016-2023
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Re: every new render produces different result

Post by Fletch » Tue Feb 07, 2023 9:59 am

First, paint all surfaces a neutral 50% grey. This should improve speed and quality from low render settings.
(This is demonstrated in the 6 Essentials video tutorial series linked in my signature below)

Next, this randomness is from low quality photon mapping or final gather settings for this particular scene. (coupled with the white surfaces = bad)
Every time you render with Easy 1-7 (photon map + final gather aka PMFG)it shoots the photons randomly. Sometimes they will hit one surface in one place, sometimes in another. This changes every time you hit render for PMFG settings.

Easiest answer is to render with Easy 09 (when coupled with a good CPU and recent model NVIDIA graphics card and Fastforward denoise you will get consistent, noise-free, and fast renderings every time. )

Albertep
Posts: 3
Joined: Mon Feb 06, 2023 7:42 pm

Re: every new render produces different result

Post by Albertep » Tue Feb 07, 2023 1:04 pm

That explains it. I will have to live with it, because the 09 render takes forever on my macbook 2016 and is too fuzzy for my liking. The low renderings deliver - quickly - the crisp result i want, but with unpredictable outcome.
The 50%grey-solution is right out: it is supposed to be white high gloss woodwork.

Fletch
Posts: 12897
Joined: Fri Mar 20, 2009 2:41 pm
OS: PC 64bit
SketchUp: 2016-2023
Contact:

Re: every new render produces different result

Post by Fletch » Tue Feb 07, 2023 7:23 pm

For white, set your color to between 70-80% grey, then use the post-process tab and choose "ACES" or "Filmic" and adjust exposure. Also be sure your lights are not too bright. More direct lights nearby will help lower or eliminate the bright spots.

Please go through the preflight checklist.
#1 rule for colors is: no pure white surfaces. If a surface is pure white, then how can it get brighter when a light hits it? A pure white surface tells the rendering engine to bounce back all light that hits it. It is not physically possible.

A professional uses 15%-80% range of brightness (in the preflight checklist it says 90%, but 80 is better) and saturation for all colors and textures coupled with proper post processing settings. This leaves room for colors to get much brighter in sunlight and darker in shadow.

This will also cause less errors for the engine to attempt to correct and results in faster render times.

Albertep
Posts: 3
Joined: Mon Feb 06, 2023 7:42 pm

Re: every new render produces different result

Post by Albertep » Fri Feb 10, 2023 11:19 am

Thanks, usually i just jump in and try, but with this, proper preknowledge is essential. I get better results now.
Still a lot of trial and error to do though...

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