How to render tyCache with motion blur?

[Alexx31]

Hello,

I remember that tyCache needs to be rendered as instances, which is the default setting, when I export particles to tycache.

But I couldn't manage it, to get it rendered this way, it's invisible for Vray. Which settings have to be changed?

Putting a modifier on it, will turn it into mesh and makes motion blur impossible. I have a scene with actors, which I want to retime much faster in order to get more motion blur.

Thanks!

[tyFlow]

Which version of VRay are you using? And are you using IPR? tyFlow doesn't currently support IPR rendering due to issues I'm hoping to have fixed soon.

Turning to mesh should only be problematic for motion blur if topology changes over time.

Edit: oh I think this is the scene you emailed me right? I will look further into it soon and get back to you about it.

[Alexx31]

I'm using Vray5 and Max 2022
and IPR to check it and then I render it later out in bucket mode.

In an actor scene I guess no topology will change.
For a different scene with particles with fracturing the topology will for sure change.

- So I understand that I should not use the tyCache ("export as particles") when using fractured particles, because their topology changes and I wouldn't get motion blur?

- For the actor scene I just couldn't find out, how Vray can render anything as instances, without having to "render as mesh" or putting an edit poly on it.
(for sure a simple basic thing?)
It's just interesting, if I could render cached actors this way with motion blur.

My aim is to render a cached scene with motion blur.

[tyFlow]

Fractured particles and non-actor/non-cloth particles will render fine with motion blur, when rendered as instances. Actors should also render fine with motion blur too. The only time you'll break motion blur is if you convert to mesh and have topology changes. Also I think a final exception to that rule, is that actor animation imported as deformations (not a skin rig) might not have moblur when rendered as instances. I can't remember if I implemented that or not and I can't test right now because the VRay implementation of my dev builds is currently broken (because I'm working through some IPR fixes that broke production rendering code).

The fool proof way to get motion blur on a cache would be:

1) ensure no topological changes over time on anything in the cache
2) place a mesh modifier on the cache (ex: Bend - all settings can be default...this is purely added to disguise the baseobject) and disable GPU instancing/render instancing/vray interface/particle interface in the cache

At that point all renderers should treat the cache object as a 100% mesh with no tyFlow influence or control. It should render with motion blur the same way any other deforming mesh in max would.

And an even further foolproof way would be to create a tyMesher, place in 'input geometry' mode, under particles disable the 'force interface' setting and then select your cache object. VRay and other renderers have no way of know that a tyMesher is a tyFlow plugin (because it doesn't expose the tyFlow interface)...so they would be 100% forced to treat it like a normal, deforming mesh...with all the same rules and conditions concerning moblur.

[Alexx31]

Great, both worked.

It seems to be no speed difference between both methods.
In the IPR quicktest the tyCache method seemed a tiny tiny bit more smooth, but here I'm speaking just about details when zooming in, that will maybe nobody see.

(anyway a IPR is maybe no good test

The tyMesher is quite handy, when working with multiple tyCaches in the same scene.

[tyFlow]

Glad it worked out!