I'm reading points with velocity from disk at integer frames (i.e. no sub-frame data exists). Turning on ‘Geometry Velocity Blur’ on the object level gives me great LINEAR motion blur in mantra. Is there a built-in Houdini way of rendering CURVED motion blur, where the rendering considers more time-steps? Increasing the ‘Geo Time Samples’ on the mantra Sampling tab isn't doing it, as I had hoped.

Thanks for any tips.

The closest out-of-the box solution I've seen was blogged by this fellow:
http://ihoudini.blogspot.com/2009/08/multi-segement-motion-blur-with.html [ihoudini.blogspot.com]

It'd be great if you could toggle something on the object to tell Mantra to use ID instead of point number but I don't know if that is feasible.

Thanks for the tip, Jesse. If I understood right, that fellow's solution requires oversampling a sim, which I can't do because I'm reading points from disc.

I've almost arrived at a solution, but need some help wrapping it up. Basically, I'm reading a point's previous, current and next frames and drawing a spline between them. My network looks something like this: TimeShift SOP to retrieve prev and next frames, Add SOP to connect points as poly, Fit SOP to convert it to nurbs, Carve SOP to trim to proper length. Two questions remain:

1) How can I drive opacity of my rendered curve by a point attr? In other words, I want to scale opacity of the rendered curved by length of velocity. Creating an “Alpha” point attr, doesn't seem to get read by my material.

2) Need some way to check if a previous or next frame exists for a particular particle id and if not, extrapolate one. Not sure which SOP to look for here.

Thanks for any tips.

grhart
…f I understood right, that fellow's solution requires oversampling a sim, which I can't do because I'm reading points from disc.
…

you don't need to oversample the sim
the only thing you need to do is make sure your particle count is constant over all frames
then the deformation motion blur will be used (if you have velocity MB unchecked) and if you have more than 2 deformation samples then it will be curved