Flicking Lighting

[Otuama]

Hi all

I'm having an issue with a shot where the lighting is flickering.

I'm rendering 4 scenarios of the same camera shot - just different things animate in/out

The other 3 seem to be ok, 2 certainly are.

All these shots are based off the same master scene.

I did have this issue with another of the shots but turned off Adaptive Light Sampler, which often fixes issues like these.

However this scene still has the issue.

I have a deadline for Monday and can't afford to have these issues.

Does anyone have any suggestions.

I could maybe turn the sampler to Precise instead of Adaptive

It may be a bit hard to see in the screen recording I've done.

Thanks

[Otuama]

Hi,

I've just realised I posted the exact same issue 12 days ago ( https://forum.corona-renderer.com/index.php?topic=42676.0) .  These last couple of weeks have been a blur due to the workload I have on :( .


Based on the replies in the above topic.

You have to precalculate uhd cache for animations. Here's a link with more info: https://support.chaos.com/hc/en-us/articles/4528617365649-How-to-use-the-UHD-Cache-for-animations-and-stills-in-Corona-for-3ds-Max

If you don't want to play around with that. Then just switch to path tracing, slower but less problems.

We've probably rendered hundreds of animations so know the process but there are those few jobs (this being one of them) that cause a headache.

I've never used path tracing as a secondary solver.  We've always used UHD.  The results may be better with secondary being at path tracing, but based on the example in that link I can't justify double the render times.


For all animations we use UHD with 'try to load and append' & 'load file'

The increment we use depends on what we're rendering. 

For the animation above I'm using Nth = 10 - We generally use 20-25.

For animated cars/people I use between 10 & 20.

We always use denoising for animations (set to Corona High Quality (0.6 - 0.7)).  We also use a denoiser in After Effects because we render animations to 6% - 8% (depending on the job).

All of our jobs seem to suffer at the final stage because we work with large developments, lots of vegetation, long animations etc etc so we need to keep our render times down as much as possible.  We also have multiple jobs on at the same time with crazy deadlines.

Reading that page it looks like denoising isn't recommended for animations.  On the flip side to this, if we turn denoising off we'll need to have our percentage turned right down and that brings us back to longer render times we can't afford.

https://support.chaos.com/hc/en-us/articles/4528617365649-How-to-use-the-UHD-Cache-for-animations-and-stills-in-Corona-for-3ds-Max

Something we've never done is calculate from scratch for every frame.

As mentioned above we render every 10-25, even if we don't technically need to - this comes from years ago where Vray was less forgiving and we had issues.

As we use network rendering (14 systems), would it be advisable to do one or the other of these:

• Calculate from scratch (discard) on each system
• Calculate from scratch (save/try to load and append/load) for every Nth 1 or Nth 2 frame

The second one means that all systems will use the same UHD cache which has a lot more info that we normally create.

Thanks

[Otuama]

I'm at a point now where I'm just testing based on the info I've read.

This is creating a cache from scratch (discard)

I can tell it's still going to happen after only 2 frames.

Next I'll try path tracing for secondary solver

[maru]

How many passes are you rendering here? My thinking is that maybe the base image quality is not good enough for the denoiser to make the final result flicker-free. Does it also flicker with denoising disabled? You could also try with the Intel denoiser - it is surprisingly "stable".

If it renders without flickering when using path tracing only, that would mean that the problem is with the UHD Cache.
In a case like this, I would probably try saving the cache from a single frame and re-using that single cache for all frames (since almost nothing is moving).
If that fails, I would try with Load+Append.

You can also try switching to 4K Cache and rendering a few frames - perhaps in this case it will perform better.

Lastly, maybe there is some issue in the scene itself. For example, z-fighting or a light reflecting off something extremely shiny. You can submit a new ticket here and attach your scene: https://support.chaos.com/hc/en-us/requests/new