Author Topic: shadow artifacts  (Read 184 times)

Offline digitalguru

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shadow artifacts
« on: June 13, 2019, 10:07:44 PM »
Hi,

Getting some artifacts in a test render in the shadows, which I'd thought I'd solved by setting Ray Detail Region Padding (Detail in Camera - 0.5):


It's tricky to diagnose in a crop render though, as it looks like these artifacts occur around the edges of the render buckets and in a crop render these obviously change.

Just tried a few tests and turning off Stabilise Ray detail in motion gets rid of them in stills, but just wondering how that might affect the animation.

Going to try some tests with that turned off for a crop render (will still take a while to render though) and just wondering if I'm looking in the right area to fix it.

p.,s just to note this is a crop of the render at left edge of the frame.
« Last Edit: June 13, 2019, 10:11:30 PM by digitalguru »

Offline Oshyan

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Re: shadow artifacts
« Reply #1 on: June 13, 2019, 11:03:44 PM »
Those look like bucket boundary issues to me. That doesn't necessarily tell you specifically what would fix it, but it might help point in a direction. To eliminate Ray Detail Region issues I'd use 360 "optimal" on some tests and see how that does. I honestly don't know enough about how "Stabilize Ray detail in motion" works to say for sure, however I think it may still be experimental and is more aimed at optimizing render times (AFAIK). Historically disabling it seems to solve similar issues, so you're probably on the right track:
https://planetside.co.uk/forums/index.php/topic,20626.0.html
https://planetside.co.uk/forums/index.php/topic,16336.msg161564.html#msg161564
https://planetside.co.uk/forums/index.php/topic,21427.msg215128.html#msg215128

- Oshyan

Offline digitalguru

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Re: shadow artifacts
« Reply #2 on: June 13, 2019, 11:22:35 PM »
Good to know - I'm trying 360 "optimal" and stabilize off on a test now  :)

Thanks for the posts, very useful.

Also noticed a reply from you:
Quote
for noise in vegetation you'll want to lower your AA noise threshold a bit and/or not use 1/64th adaptive (1/16th is probably OK)

That was made a while ago (2013) - does that still hold true in light of Robust sampling? (TG V4.3.23)

Offline Oshyan

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Re: shadow artifacts
« Reply #3 on: June 13, 2019, 11:28:02 PM »
Not necessarily, no. I think Robust should handle this better, although more so under 4.4 as it's been notably improved from 4.3. For 4.3 you might still want to heed that advice.

- Oshyan

Offline digitalguru

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Re: shadow artifacts
« Reply #4 on: June 14, 2019, 02:07:05 PM »
Did some tests last night, and I think turning stabilize off  "fixed" it - but those these were 10 frames tests on a crop render.

I did a control version with stabilize left on and some artifacts were visible, but not as pronounced as the full frame version - it might just be that as the render was cropped, the buckets were smaller and so the artifacts are not so obvious.

I think the 360 region padding is a good option to leave on though.

I'll try a full frame segment tonight.

Just out of interest, what kind of speed improvement could there be (if any) with the new sampler in the 4.4 versions? (particularly with sampling vegetation)
« Last Edit: June 14, 2019, 02:09:35 PM by digitalguru »

Offline Oshyan

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Re: shadow artifacts
« Reply #5 on: June 14, 2019, 05:29:45 PM »
I'm not certain the effect on vegetation but the sampling improvements basically give you better quality, which allows you to adjust and better balance the noise threshold. There are other rendering optimizations in 4.4 as well, for example with some cloud rendering scenarios. Check out the newer Terragen 4 benchmark and there are a few like-CPUs that show the difference there on 4.3 vs. 4.4. Look at the multiple Threadripper results for example, particularly the 1950x:
https://planetside.co.uk/terragen-4-benchmark-results/
So if you *can* use 4.4.18.f it'd be ideal to do so, I believe. We haven't seen any notable stability issues, it's been in Frontier for a while.

- Oshyan

Offline digitalguru

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Re: shadow artifacts
« Reply #6 on: June 14, 2019, 06:57:30 PM »
Quote
Look at the multiple Threadripper results for example

Good point - hadn't thought of that  :)

I have a Threadripper 1950X - I see the difference between 4.4 and 4.3 at the same clock speed is just over a minute, that's great if it's accurate.

Offline digitalguru

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Re: shadow artifacts
« Reply #7 on: June 20, 2019, 03:55:03 PM »
I ran a short test with stabilize off on full frames and the artifacts have gone - going to send the full version to Pixel Plow and see how that turns out.

It did add significantly to the render times however, almost 20% in some cases.

So I upgraded my maintenance to get Frontier build 4.4.18 and render times are now back to where they were previously  :) Nice! The updated robust sampler really makes a difference.

Also, like the automatic renders have the render time built in  - really handy for debugging.

Offline Oshyan

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Re: shadow artifacts
« Reply #8 on: June 21, 2019, 07:32:18 PM »
Nice! Glad you found the upgrade immediately worthwhile. :)

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