Hello dear forum,

every time I lower the Time Scale of a sim (vellum & RBD), the motion blur gets terribly wrong and way to slow and long.

What am I missing here?
It's the best function ever and I'd really like to make it work with the right motion blur.

I am in H19.5.640 and using Redshift.

Any hints are greatly appreciated.
Thank you!

Sounds like you are using velocity motion blur, which may be unnecessary for constant topology geo like vellum or RBD usually are


But regardless, changing timescale doesn't have an effect on velocity attributes, velocity stays in unit per second
So if you want to correct it, multiply v@v and v@w by the same number as your timescale post sim

Tomas, you are a life saver.

It's due to my strategy for rendering in Redshift.
I do an object merge for each render object on the OBJ level.
If I don't activate velocity MB on these render geo containers, it doesn't work at all.

Will try your approach, which sounds totally logical to me.

Thank you!

I'll report back if it didn't work.

I don't know about RS, but usually enabling Deformation motion blur (with at least 2 samples) should work for static topology geo regardless of whether it is all merged in a single object or not, just make sure there is motion between frames, and if not you can use Timeblend to interpolate

so that's why you shouldn't need velocity, if you are ok with the limitations of velocity motion blur, then you can continue using it and just correct the values

Thanks, Tomas!

Yeah, RS works a little different here, sadly.
You can only bring in MB from the v attrib once you object merge a geo.

Should someone know how to prove me and RS wrong here, please do so! I'd much appreciate it.


I found a very simple solution, though, for now.

Just set whatever value you chose for your sim's time scale in the following parameter field of RS's own Motion Blur settings as well: "Frame duration".

All done.