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Motion Blur Question

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Motion Blur Question

Unread postby tom_tm » Fri Feb 12, 2021 5:08 am

Hi,
I have to render some fast self rotating objects which have a cylindric shape.
The rotating axes are 100% centered in the y Axis.

Why does a Cylinder get so blurry on the top?
I need to render some CNC-Drilling Stations.

I attached the scene.
Attachments
testmb.zip
(210.35 KiB) Downloaded 28 times
3D_Motion_Blur.jpg
no_3D_Motion_Blur.jpg
tom_tm
 
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Re: Motion Blur Question

Unread postby aaute » Fri Feb 12, 2021 10:40 am

Hi,

I did a quick test with your scene and the problem come from your abc export without enough sub-sample and deforming (interpolating) the geometry between key frame.
To counter this, I froze the animation on the first frame and linked the object to a locator, and the problem is gone.

Image

Maybe try to re-export your geometry with more sample, or keep the hierarchy in your animation package.

Cheers
Attachments
mb.7z
MotionBlurFix
(84.59 KiB) Downloaded 29 times
Aymeric
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Technical Artist - Clarisse Specialist
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Re: Motion Blur Question

Unread postby tom_tm » Fri Feb 12, 2021 1:21 pm

Hi aaute

Thanks for your input. I found the "problem"
I didn't tick the "Use Motion Blur" in Houdini's ROP Exporter.
If I do so, then I need to to chose Motion Blur Mode "Use Sub Positions"

But what is the option to "Compute Velocity" out of an alembic then?
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Re: Motion Blur Question

Unread postby aaute » Mon Feb 22, 2021 2:57 pm

Hi,

- read velocities : just take into consideration what have been exported (based on the sample you define in your DCC)
- compute velocities : based on the MB Sample count, Shutter Begin, Shutter End you defined in the path tracer.
Most of the time if you place the mouse over an attribute you display the tool tip, giving you a quick definition of the different options.

Cheers
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