I'm animating car wheels in Solaris for a layout and hit a problem with the motion when rendering in Karma. There are only two motion steps no matter what I do.
It seems the RenderGeometrySettings node has no effect on the result. Is there a way to fix this?

flord
I'm animating car wheels in Solaris for a layout and hit a problem with the motion when rendering in Karma. There are only two motion steps no matter what I do.
It seems the RenderGeometrySettings node has no effect on the result. Is there a way to fix this?

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Yeah, the motion steps on the renderer are useless as the result is already interpolated by hydra from the timesamples before the renderer gets the data. The only way I have found is by having every motion sample exist as a time sample as well.

And how do you do that?
Adding a key frame every ⅒ frame doesn't work.
Thanks!

flord
And how do you do that?
Adding a key frame every ⅒ frame doesn't work.
Thanks!

On the usd rop used to write the layer that's being read back, set the time steps to correspond to the number of motion samples. Alternatively, the cache lop has a substep value too.

At least, this is how I remember it working.

I'd recommend using the Cache LOP, especially when only parts of the scene have extreme motion blur, to get enough samples into the renderer.

There's a similar thread (https://www.sidefx.com/forum/topic/74521/) which might be useful

Ok so all I was missing was to set the increment properly on my cache LOP.
I always thought we didn't need several substeps for rotation motion blur, but it seems it's required with Hydra/Karma.

Thanks everyone!