CoronaMultiMap seed changes with animated camera

[dzintas]

Got a problem with a animation where materials with multimap changes between frames. Wanted to clarify few things without creating new topic.
My guess this happens cause seed number is set to 0, so when rendering each node just randomly uses different seed number?
If so then changing seed to something like 123456 would lock it in and material wouldn't change in between frames?
Problem happens only with objects that are animated, if it's just moving camera then materials don't shift around.

[TomG]

Definitely a case where a new thread would be better ;)

[romullus]

Shouldn't happen, AFAIK 0 in Corona is just another valid seed, unlike in some other programs where seed 0, or -1 means random seed on each evaluation.

Splitting and moving the messages to bug reporting board.

[dzintas]

Shouldn't happen, AFAIK 0 in Corona is just another valid seed, unlike in some other programs where seed 0, or -1 means random seed on each evaluation.

Splitting and moving the messages to bug reporting board.

Thank you for cleaning up my mess, and clarification!
Tried changing to some specific seed value, and as you mentioned bug still happens. Maybe less but just could be a different pattern.
Then its maybe problem with my setup. It's tyflow animated object, exported to vray proxy.
Maybe vray proxy part causes problems? It's building shaped boxes with a lot materials for facades, roofs, etc. Plus color variations for diffuse, with multimap that causes problems.

[romullus]

If you are able to provide simplified scene where the issue can be reliably repeated, i think that would be very helpful for the team to identify and maybe fix the issue. https://support.chaos.com/hc/en-us/requests/new

[d4l1]

Try to put the object (with the Material / CoronaMultiMap applied) on top of your hierarchy - on the first position in the Outliner / Objects list. Your problem sounds somewhat like we faced a few months ago and this was the solution to that. Really random stuff. Maybe this workaround helps with your situation too. :D We had a Cloner that changed random values ...

Edit: Just saw that your problem is within Max. Sorry! We're working with C4D .. but maybe it works even in another software. :)

[maru]

I don't think we are aware of this issue. Please do submit a support ticket and provide basic information such as:
- Which exact version of Corona you are using?
- Which exact version of 3ds Max?
- Are you using some 3rd party plugins in your scene?
- Attach the problematic scene (or a simplified version of it)
You can do it here: https://support.chaos.com/hc/en-us/requests/new

[dzintas]

I don't think we are aware of this issue. Please do submit a support ticket and provide basic information such as:
- Which exact version of Corona you are using?
- Which exact version of 3ds Max?
- Are you using some 3rd party plugins in your scene?
- Attach the problematic scene (or a simplified version of it)
You can do it here: https://support.chaos.com/hc/en-us/requests/new

Sorry for a late reply, uploaded cleaned up scene id:  #239077

Did tested it out a bit more, and it happens on single pc to. Not only on different render nodes, as I suspected in the first place. Just didn't notice it.

[Aram Avetisyan]

Hi,

I have checked the scene and unfortunately this is expected given how the VRay proxy is animated.
The number of faces (and effectively their indices) changes, and so does the randomization.

I think the workaround is to have different IDs for the roofs and randomize by Material ID instead of Mesh Element.

Hope this helps.

[dzintas]

Hi,

I have checked the scene and unfortunately this is expected given how the VRay proxy is animated.
The number of faces (and effectively their indices) changes, and so does the randomization.

I think the workaround is to have different IDs for the roofs and randomize by Material ID instead of Mesh Element.

Hope this helps.

I'll try it out if encounter this bug again. At the moment just smoothed over the flicker in post and work on it is finished for now. Unless we get some revisions.
About the process, for example my roof material. I need to create multiple material id's for same roof material just to have some randomization to happen?
Kind of complicates the process a bit.
Other thing, would this happen if I use point cache or corona proxy instead of vray proxy?

 

[Aram Avetisyan]

No no, I think you thought about it more complicated than it is.

What I proposed it to simply have IDs for polygons and assing them specific static materials, without randomization. This can be done either through separate materials either with CoronaMultiMap with Material ID mode, without other options to randomzie.

The reason you are getting different texture each frame is that because of the animation, there are different number of faces on each frame. E.g. the randomization happens for 10 faces, then for 11 faces, then for 12 etc, which effectively changes the seed.

But this will not be the case if the polygons have specific materials assigned to them only through IDs, which stay intact regardless of number of faces and animation.
You can try simply disabling all randomization modes for CoronaMultiMap and enable only "Face material ID". This way the intended look may change, but materials will be locked in place from start to finish of the animation.