Ocean sim with foam and splashes flickering at backup interval.

[oophus]

interesting. you are sure that exactly the backup interval is related to the problem? because aweek ago i was pursuing a bug appearing at every 15th frame, that was a coincidence and had no relation to the backup

Well I assumed that was the case. There are some flickering between the backup frames as well, but thats not that noticeable as per the 15'th frame so I though that came from the render it self as its not that high in settings because of time restraints.

I'm at home now for the weekend, so I wont be able to test more until monday, but I would really appreciate it if you found a solution to it by then as I have at least 6 more scenes to render with different splah/foam simulations.

[oophus]

yeah happened to me too. I've simmed without any backup intervals then it was correct. Perhaps double velocity in 15th frame?

From what I can see it doesnt look like the particles get out of wack by double velocity. It looks like they get rendered by half opacity or something like that. Like if you put the diffuse multiplier down a notch.


PS: On the new render, the flicker only happened at frame 1600 in a render between 1550 and 1750. So since I put the backup per 200 frame, it looks like it definitely are the backup interval that causes this.

[Ivaylo Katev]

rodger, hopefully in few days you will have the answer. actually i'm thinkink about some settings pre render check to show warning in such cases, sometimes it's complicated to find the reason even for advanced users

[oophus]

Any news on the development on this? Was it a bug, or something else on my part?

[Ivaylo Katev]

not yet, even if is an user side mistake, we have to add a warning

[Ivaylo Katev]

ok, the bug is found, hopefully tomorrow will be fixed

[oophus]

Goodie! Just in time for a new calc, and render to morrow.

[Ivaylo Katev]

the splash/mist wall issue is also fixed, you can simulate with air drag now. the issue was related to the environment air simulation, it was on by default. now there is a switch to enable/disable it.

[davemcd]

ok, the bug is found, hopefully tomorrow will be fixed

Just checking on this bug as we've been encountering backup interval flicker on a current job (nearly every sim we've done) v3.05

Are there any render setting ways to fix it without having to resimulate the shots with backup turned off?

For us the effect basically end up with extra micro details in the sim, so reflections especially at low angles pick up extra details causing a pulsing effect on playback

Cheers,

Dave

[Svetlin.Nikolov]

Hey,

Please note that the backup frames just contain channels that are not exported by default but you could enable manually and you should enable them if you need certain effects. For example, if you want motion blur, you should enable grid and particle velocity. If you need retiming, you should enable particle IDs, etc.

It's not a solution to turn backup off, but to enable the proper channels in the Output rollout taking into account what render effects you will need later. All issues related to flickering on a backup frame so far were caused by not enabling a certain grid or particle channel and ignoring the warning messages that pop up later in relation to that. You can check more about what grid and particle channel is needed for what effects here: https://docs.chaosgroup.com/display/...utputParticles

Would it be possible to share shots of your Output rollout and especially the Simulation Cache File Content box for a non-backup frame. If possible, a video of the pulsation you are encountering would be very helpful as well. Please also paste the build ID from the Simulation->About box. We have to make sure that the issue is caused by missing channels in the first place and is not something different.

Cheers!

[Ivaylo Katev]

Hi Dave,
in the most cases the backup flickering is caused by velocity used in the render setup, with no velocity exported in the output setup, that is technically not a bug (but is still annoying), the bug mentioned in the post was a real bug, causing flickering even if the user has proper setup.