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Motion Blur Karma vs Mantra

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jerry7
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Hi,
I use the same time samples for karma and mantra.
The motion blur for mantra looks better than karma. The mblur of karma seemed not being interpolate as good as mantra.
Must I set more time samples for karma to get the same quality? Are there some other tweaking parameters?

Thanks!

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mblur.png (62.6 KB)

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Soothsayer
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Try to play around with cache nodes especially if you apply transforms in Solaris.
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jerry7
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Soothsayer
Try to play around with cache nodes especially if you apply transforms in Solaris.

I uses the Karma rop HDA， that has already cache inside. The rendered image shows the mblur worked, but is not interpolated smoothly.
Edited by jerry7 - 2023年4月12日 04:48:21
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jerry7
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I uploaded a hip to show the problem.

Attachments:
mblur_karma_vs_mantra.png (574.5 KB)
mblur_karma_vs_mantra.hipnc (674.3 KB)

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Soothsayer
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If I use $FF instead of $F I get this.

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Screenshot at 2023-04-12 14-21-17.png (1.1 MB)

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jerry7
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Thanks! I got it.
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jerry7
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It still has problems at specific parameters value.
Edited by jerry7 - 2023年4月13日 00:40:43

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bug.png (446.7 KB)

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jsmack
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jerry7
It still has problems at specific parameters value.

Your camera shutter needs the same alignment as the samples. Without a camera primitive or karma render settings, it will use the default. By specifying time samples in a smaller window than the render, you're telling the object to be stationary for part of the shutter window.
Edited by jsmack - 2023年4月13日 01:12:16
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jerry7
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jsmack
Your camera shutter needs the same alignment as the samples...

I added a camera, the problem still existed.
Edited by jerry7 - 2023年4月13日 02:05:22

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bug.hipnc (144.8 KB)
bug.png (303.2 KB)

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Soothsayer
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If you increase the samples in the cache node to about 10 it looks much better but I don't really understand the behavior.
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jsmack
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jerry7
jsmack
Your camera shutter needs the same alignment as the samples...

I added a camera, the problem still existed.

Cache LOP seems to be broken. If I set time samples on the node that creates them, it works fine.

Edit:
This is truly a bizarre issue. The usda files are nearly identical. The only difference is that the cache lop seems to write the time samples with full 64bit precision where as the time samples created on the transform appear to have been 32 bit at some point before recording at 64.

Cache:
0.85: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -1.15, 0, 1) ),
1: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -1, 0, 1) ),
1.15: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -0.8500000000000001, 0, 1) ),

No Cache:
0.8499999940395355: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -1.1500000059604645, 0, 1) ),
1: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -1, 0, 1) ),
1.1500000059604645: ( (1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, -0.8499999940395355, 0, 1) ),
Edited by jsmack - 2023年4月13日 15:54:58

Attachments:
Screenshot 2023-04-13 124020.png (94.6 KB)
karma_mblur.hip (503.2 KB)

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jerry7
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Thanks, I reported a bug report.
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