Hello,
I have a test scene for learning Geo Time Sample.

In this scene, there are two object. One is particle(deleted v attribute) , other is switch sop which change topology.

The two objects both are changing topology with time. But why one has motion blur and other has no?

Thanks!

In the Motion Blur operation , Houdini using floating frames , not integer frames , for examplefrom frame 1 to 2 (in geo samples 4) , Houdini do sample from frame 1 , 1.25 , 1.5 , 1.75 and frame 2 , in this case it can compute object's direction.

in the Particles , because they have floating animation between each integer frame , Houdini can compute their velocity even for 1 frame .

But in the Switch SOP method , your points changed immanently on frame 2 , (They are constant) , so the point's position for frame 1 , 1.25 , 1.5 , 1.75 are same and they change only in frame 2 , in this case Houdini can't compute Motion Blur !

I made a simple project about this for you , please check it :wink:

I got it! Thank you Joker386!