Camera Motion Blur and Interval center

[KramSurfer]

Does adjusting the interval center directly affect the 'time' of the Geometry sample?

Example: if at slider time 10, duration 2, Geometry Samples 2 :

With an interval center of -1, the geometry sample time would be 8f to 10f ?

With an interval center of 1, the geometry sample time would be 10f to 12f ?

Can someone confirm or correct my thinking?

Thanks

[joconnell]

Yep, it determines where the "middle" of the motion blur is. Say for example we have a motion blur duration of 1, or a full frame and have our interval centre set to 0.5, this means we're rendering our object between our current frame and the next one. In your example of rendering frame 10, our object will be centred at where it would be at frame 10.5 with a bit of motion blur ahead and a bit behind. For any live action matchmoving work this is an issue and we always set our interval centre to 0, as we want our object to render with it's motion blur centred on the frame, which is what a matchmoving program will output.

The only caveat of interval centre 0 is that if you render frame 0 and if there's no animation before, and you haven't used any out of range types on your animation curves, vray will have nowhere to start it's motion blur calculation from and you end up with a weird looking frame.