Hi,I have a very basic scene about RBD fracture. I know if I unpack them the motionblur would work correctly in Karma,But I would like to konw how can I get motionblur correctly but dont unpack them ? Because if I have lots of fractures , unapck would be lots of polygons.

Is Karma not support instance motionblur?

I have attach a hip file,thank you for your help

velocity MB is usually used instead of Deformation MB usually with geometry or point instances that change topology

you are importing packed primitives as native instances, each instance has Xform primitive so it can use Transformation MB with no issues

To render it however you need timesamples, which you can create using Motion Blur LOP or Cache LOP or writing it as a single .usd to disk

alternatively if you want to force velocity MB
you can choose Create Point Instancer for Packed Primitives on your SOP import
OR
you can use Houdini Procedural: RBD LOP

tamte
velocity MB is usually used instead of Deformation MB usually with geometry or point instances that change topology

you are importing packed primitives as native instances, each instance has Xform primitive so it can use Transformation MB with no issues

To render it however you need timesamples, which you can create using Motion Blur LOP or Cache LOP or writing it as a single .usd to disk

alternatively if you want to force velocity MB
you can choose Create Point Instancer for Packed Primitives on your SOP import
OR
you can use Houdini Procedural: RBD LOP

Thank you for your reply .After I check "Create Point Instancer" on SOP Import node MB works.

And May I ask one more question? When I import every fractures as one point just like this , How I can assign different material between inside faces and outside faces?