Scatter instances move between frames when Camera clipping enabled

[Ink Visual]

Hi,
We recently rendered animation with dozen of scatters. As the parsing times were growing, we decided to try the active camera clipping option for a higher density ones (grass lawn, hedges etc).
At first glance it worked fine and reduced parsing times a lot for some of the sequences, however later we noticed that with clipping option enabled, scattered objects started to move between the frames.
Activating temporal consistency did not help.

Please see attached videos for comparison between the clipping option ON & OFF.

Max 2022, Corona 8 and Corona 9 (same issue on both versions).

[maru]

Hi, most likely what we see here is not related to objects (they are not disappearing or changing positions), but to materials. This can happen when using the Corona Multimap. When using Camera Clipping, the "pattern" generated by the Multimap changes per frame, so the colors are assigned differently. One workaround I can think of is removing the Multimap from the materials of the scattered objects.
I will check if we have some other possible solutions and will return to you.
This is also a known issue and it should be fixed in the future versions.

[Ink Visual]

Hi Maru,
I see, thanks for explanation, that makes sense indeed. I don't remember if we had Multimap texture in this shader but it's very likely, will test it soon again.

If that is the case though, and it's a known issue, would be great to have it listed as a limitation on Corona Support page, next to Camera Clipping description.
Would have saved us time spent on trying to figure out what's wrong (and money lost on render farm).
Cheers!

[maru]

So after a quick chat, we are not aware of any other solutions than either disabling Camera Clipping or removing the Multimap from the material tree. Sorry.

You are right about the information in the helpdesk portal. We will update it ASAP. On the other hand, this should be soon fixed in Corona 10 daily builds.

[maru]

Added as a link in the general "Known bugs and limitations" article under a new Scatter section - https://support.chaos.com/hc/en-us/articles/4528311915025-Known-bugs-and-limitations

[Ink Visual]

Hi Maru,
That's great, many thanks for addressing this!

[maru]

This is fixed in the newest daily build. If possible, please try it and let me know here if everything is working fine for you (but please do bare in mind all the risks of using daily builds) - https://forum.corona-renderer.com/index.php?topic=38385.msg208744#msg208744