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johnm

alembic and motion blur

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How does one properly export deforming geometry from maya and import it into houdini in such a way that deformation motion blur works correctly with a 0.5 shutter interval?

Maya's alembic export settings: step size = 1, and FrameRelativeSample = 0.0 and 0.5

houdini is set up with camera shutter=0.5 geo_motionsamples=2

I'm getting intermittent frames with no motion blur at all, and, motion blur is as though shutter=1.0.

I know I can work around the issue by lerping the geometry sampled at the integer frame values, but I was hoping I wouldn't have to.

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Yeah, Timeblend should sort you out. You may need to calculate velocity also (trail sop set to compute velocity).

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thought I'd share what I found...

First of all, timeblending the geo sampled at integer frame values (lerping translated, for all you youngsters) is fine and all, but I was looking to tap into the sub-sampled geo data.

Secondly, point velocity doesn't apply in this situation as we're dealing with deformation blur.

My problem was my understanding of what I'd get from Maya's Frame Relative Sampling.

The attached rendered pics show a camera shutter angle ramping from 0 to 1.0, with mantra's Geo Time Samples set to 5.

The Maya alembic export settings were:

-Evaluate Every 1.0 frames (ie integer frame samples)

-Evaluate Every 0.1 frames (10 samples per frame)

-Evaluate Every 1.0, with Frame Relative Sampling Low=0.0 and High=0.5

and the timeblend version is for comparison.

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