Multi sample motionblur on changing topology geometry

[Dubbie99]

Hi, I cannot seem to get multisample motioblur working for geometry that has changing topo. I have velocity on my points and I have checked that the subframe appearance is correct in houdini (it is)
Are there any secrets to getting this to work? I have 10 geometry samples set and 172 degree shutter.

I am getting this error. I thought that changing topo didn't matter if you had velocity.

[bdancer]

Is it possible to send me a scene with this object?

[Dubbie99]

I can send you a scene for sure. Where can I upload it?

[bdancer]

> Where can I upload it?

Anywhere where it's conveniet for you.

[Dubbie99]

https://mega.nz/folder/TY9XRKhR#LMFuJkqYGgPWYrnKgQ7AjA

If you do manage to get it working, I would love to get the working scene back from you.

[bdancer]

> If you do manage to get it working

Well, I'm not sure what's the issue here... Maybe you could try more recent build?
Here is render without any modifications of your scene, and it matches Mantra behaviour for me:

[Dubbie99]

I want to get subframe motion in the MB so that they aren't just ruler straight lines.

[Dubbie99]

Can you confirm if this is possible or not?
If not, I'll have to come up with some sort of hack to maintain topo

[bdancer]

> Can you confirm if this is possible or not?

Well it seems, I wrote some prototype, but it's not yet in a state to be merged.
Also I found it really difficult to have velocity sample that precisly matches,
the location of the next sub-sample vertices, so MB currently looks very jaggy.
I'll check if acceleration blur could be utilized somehow...

Could Manta render the way you want so I could have a reference?

> I'll have to come up with some sort of hack to maintain topo

I'll do my best, but if you could for now to figure out smth it'll be great.

[Dubbie99]

Thanks for your confirmation bdancer

[Dubbie99]

Just to follow up on this, I tried a little hack to give constant topo and the motionblur works nicely then.

Bit of a hack, but it works!