Motion blur with cached nParticles and Vray

[Steve Davy]

It's been years since I've done any particle work, but I have now been tasked with creating a simple hail simulation. I'm using simple nParticle spheres and want to render them in Vray.

However, seems like caching them prevents motion blur from being calculated. I don't ever remember this being an issue with particles in Maya before (though like I said it's been a long time).

I've only managed to find one post from Vlado about this, which seems to indicate it's some sort of temporal sample synching problem (didn't quite understand what he was saying) but in any case that post was from about 10 years ago so likely out of date anyway.

Does anyone have any pointers as to how to fix this? Seems like a very odd, old-school limitation to have with a renderer like Vray in 2023.

[Armin]

I am not sure, have not used vray in years but I dimly rember
that the step size of the cache needed to be set
to 0.5 or 0.25 to match the motion blur settings.
You probably tried this already.
Maybe it's time for bifrost altough I don't know how to render bif in vray.

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[Steve Davy]

Yes, caching with subframe sampling seems to be all that's required. I don't actually fully understand why it's necessary to get a simple whole frame blur but simply setting subsampling to 0.5 got me what I needed.

I've also no idea why Chaos's documentation is so completely vague about this, with a lot of waffling about interpolation and the like when all it needs to do is clearly state that this is what you need to do.

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From: maya...@googlegroups.com <maya...@googlegroups.com> on behalf of Armin <temp.op...@gmail.com>
Sent: Wednesday, May 3, 2023 11:43 AM
To: maya...@googlegroups.com <maya...@googlegroups.com>
Subject: Re: [maya_he3d] Motion blur with cached nParticles and Vray

 

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