Flickering on interior animation

Corona Corona for 3ds Max Help Required
1

Hi,

Here is my problem: I render a short animation of an interior with no moving objects. Very simple scene with just a Corona Sun + Corona Sky entering through a window, lighting a floor lamp and a plaster wall. There is some flickering occuring on the plaster wall. I want to get rid of it.
The texture of the plaster wall has intricate details so the first thing I did was to simplify it a bit by adding a small blur on the plaster texture in Photoshop so that Corona has less work to do with the sampling. also note I use only CoronaBitmaps in this scene, with Filtering > Blur value of 1.0

I also reduced ‘Progressive Rendering Limits > Noise level limit’ from 7% to 5% (ideally I want the sequence to calculate as fast as possible).

But it’s not enough visibly as there is still some noise.

Here are my settings:
_ Primary solver: Path Tracing
_ Secondary solver: UHD cache
_ Precomputation file: Load from file (initially calculated once)
_ Image filter: Tent (width 3.5px, Highlight clamping: 0) Is this filter good for animation??
_ Progressive rendering limits: none, except ‘Noise level limit’: 5.0%

My guess is I must lower down the Noise level limit but before I calculate the whole sequence again I wanted to make sure there is no other important setting I miss.

Thank you so much,

2

Can you show problematic video? If that’s an issue with displacement, then tinkering with render settings won’t help - you would need to change displacement calculation from screen to world.

3

Thanks for the help: there is no displacement, only regular bump.

4

I’m not sure you need to hit a noise level lower than 5%! We do mostly animation, and with a good enough noise level and some denosing you should get acceptable results.

For me I gave up on doing any type of Cache for the solvers when we moved to Corona. All our animations are rendered with Path Tracing for both primary and secondary. We don’t get any flickering in lighting, just noise. I know the tool tip says Path Tracing for interior is not the most forgiving for renders, but we usualy have objects moving around, lights animating and all kinds of things tha make it the right choice for us.

Now i’m not sure if we could reduce render time by baking the secondary solver, but my time and sanity are more important than messing with that stuff lol. The only thing we do is set our desired Pass Pimit based on a few still frames targeting to be around 5-10% % noise with about 0.75 denoising.

Some other things we do in our Max start file:

  • Set corona to have a bit of highlight Clamping in the system tab, and mostly use Corona High Quality filtering.
  • Lower the Max Sample Intensity in the Performance Tab.

Now I know that by doing this it will affect the physicality of the render per say, but it helps with getting rid of junk like fireflies and other artifacts, at the expense of a bit darker image that no one will ever know about :smiley:

Take all this with a grain of salt, as we have set up Corona for how we like images, how fast we need renders and overall what works for us. But in my opinion for animations where more than just tha camera are moving, it is what works here.

You should post a video of your problem, so people can give you real feedback though.

Also “The texture of the plaster wall has intricate details so the first thing I did was to simplify it a bit by adding a small blur on the plaster texture in Photoshop so that Corona has less work to do with the sampling. also note I use only CoronaBitmaps in this scene, with Filtering > Blur value of 1.0”

This should not be happening, and you should not have to blur your map like that at all.

EDIT: Here is our work if you want to see our results.
https://iamstatic.com/work-archive/

5

Thanks for your detailed answer @davemahi,

Yeah going lower than 5% for Noise level does seem weird to me too but so far it looked like the only solution I found to get rid of flickering in the plaster wall.

Your animation workflow makes perfect sense, it sounds really practical and rational, I’m going to try it, especially the clamping thing and lowering the Max Sample Intensity as well.

Now, when you say "The only thing we do is set our desired Pass Pimit based on a few still frames targeting to be around 5-10% % noise with about 0.75 denoising": personnaly instead of setting a Pass limit I would rather set a Noise level limit to make sure the noise level is consistent across all frames, but that’s just my opinion. Is there a particular reason why you prefer setting up a Pass limit rather than Noise level limit?

I will also test Path tracing for both solvers as it’s simpler than first calculating UHD cache, saving it, then calculating frames by loading the cache and crossing fingers there’s no flickering of any kind once frames are calculated and deadline is closer! So again, thanks, it sounds really cool and really makes sense.

I will try to post the resulting video with:

_ Path tracing/UHD cache, noise level 5%
_ Path tracing/UHD cache, noise level 3.8% (I’m currently calculating it)
_ Path tracing/Path thacing, noise level 5% (or more) + Highlight clamping and Max Sample Intensity tweaks

so we can see the difference.

Thanks a lot

6

I hope I could help in some way.

The pass limit thing I guess is just a personal thing, as getting some parts of our animations down to the same noise level may make render times too much for us. So we ballpark an overall ammount we can handle. If our cameras are moving fast through some complex lighting, forcing the render to hit 5% may be overkill.

But it is all just personal preference, and in the end, you have to do what you feel works for the scene.

I look forward to seeing your results, or even for anyone to step in and tell us how we can improve things too :smiley:

Cheers,

Dave.

7

Hi,

So here are 3 videos:

  1. UHD cache for sec. solver + Noise level limit 5%:
    https://youtu.be/N8VKTAl1Oss

  2. UHD cache for sec. solver + Noise level limit 3.8%:
    https://youtu.be/1qUyWtoBw2A

  3. Path tracing for both solvers, Noise level limit 5% + few other tweaks: Max sample intensity 5, Lights samples multiplier 6:
    https://youtu.be/9Kx5b2bVpjM

I’m still not pretty happy with the result as there’s still some noticeable noise/flickering occuring on the plaster wall, even with Noise level limit of 3.8%.

The last video, with Path tracing for both solvers, is interesting as render times are slightly better than the first one (UHD cache + Noise level limit 5%), plus it’s little bit less noisy, but this is not what I had in mind as a result. I’d expect much smoother result with a Noise Level Limit of 5%.

And for the second video, it’s the best one in term of noise, but it’s not realistic as render times are double than the third video so I would definitely not consider that option.

Happy to have your thoughts on how to improve noise/flickering level and/or rendering times.

8

Any way you can make the videos be able to expand to full resolution? It’s hard to tell what is noise and compression. Or are these rendered out at this size?

9

Did you use denoising? It looks like this kind of noise should be easily removed with Corona HQ denoiser.

10

For this kind of noise we also use Davinci Resolve (Studio Version). It’s denoising tools for videos are brilliant and solve issues like this in seconds.

11

Frames are rendered at 1080p 25fps. I use Media Encoder with YouTube 1080p MP4 preset. Then I uploaded these to YT.
If you know another to share/show the videos, happy to do this.

12

Yes, definitely: I used Corona High Quality Denoiser.
Look at the videos directly on YouTube: in the description field I wrote down the rendering parameters.

13

Thanks a lot. I will try it.

14

I have a few questions:

  1. Which version of 3ds Max and Corona are you using?
  2. Have you tried loading the cache from file? https://www.youtube.com/watch?v=SjItQiCY2fk&t=315s
  3. Have you tried 4k Cache as a secondary solver?
  4. I see that you are using DOF. Can you try rendering it without DOF but using a Z-depth pass and apply DOF in post using the Z-depth render element?
  5. are you using the Animation(Flicker Free) setting in the UHD cache?