Gang:

Anyone ever run into this? I’ve got a Solaris scene with velocity blur that appears correctly in the viewport, but is completely missing in rendered files. I’m using a USD Render ROP to generate the images, and the “Instantaneous Shutter” parameter is off. Any strategies for how to troubleshoot this would be welcome.

Cheers,
Tim

Yes same issue here! Mb visible in viewport cpu and xpu but not in the final render or Mplay. Any solutions please? Thx

Have you added motion blur lop before USD Render ROP?

Since posting this, I’ve discovered that - at least in my case - the viewport seems to render at 24fps when using Solaris, no matter what frame rate you have chosen in Global Animation Options. The attached file demonstrates this - it contains a box that’s moving at 10m/s, with the frame rate set to 1fps and the shutter open for the entire frame. If you render to disk, the box correctly produces a streak that’s 10m long. In the viewport, the box appears to move roughly 0.4m. That’s consistent with a frame rate of 24fps (10m/s / 24fps = 0.416m). Tested with 20.0.590.

I’ve filed this as a bug with SideFX, but I always encourage others to file bugs too.

Cheers,
TIm

Sample file.

Just to finish the thought - the reason this led to the original post was that I was working with higher-than-usual frame rates and hadn't calculated how far my objects were supposed to move in one frame, so when I adjusted my shutter duration to display pleasing motion blur in the viewport at the (incorrect) low frame rate, it was too subtle to see in rendered output with the (correct) high frame rate.

My current workaround is to set the desired shutter duration for rendering on my camera(s), then add a branch at the end of my network with an Edit Camera LOP that calculates an adjusted duration for 24 FPS. Then, I have to remember to select that branch to visualize the correct results in the viewport.

Cheers,
Tim

I have submitted a bug report.

Happily, SideFX reached out to me yesterday, and this is fixed in 20.0.609.

I have a related problem - this is the closest topic I can find.

I've been doing lookdev on a scene that needs very heavy motion blur for something spinning very fast and it was looking great in the XPU viewport, also flipbooking. However if I render with a USD Render LOP I get MUCH less blur. I've tried all sorts of things, MBlur LOP, cache LOP, different settings on those but I can't figure out how to get a match to my viewport.

This pair of images are using the same settings, the one with the heavy blur is XPU viewport, the other is with USD Render LOP. Instantaneous shutter is off. You can see in the top right corner there is a very small amount of blur...

Thanks for reading

I'm with 20.0.724 and same issue. I see motion blur on viewport (Karma XPU), but final render comes out without motion blur. Did this bug came back?

It's not a bug as such. Rob from SideFX kindly explained how to deal with it here :

https://www.sidefx.com/forum/topic/96619/#post-424765 [www.sidefx.com]

Thanks for fast reply. Must be something else since no matter if I put 0.5 or 10, nothing changes.

What about if you set Filter Time Samples to 'Never'?

Same result without motion blur. Solaris is so frustrating.
Thanks for your help.

If you can put your scene on here if it's not too complex I'll have a quick look - I'm no Solaris expert either though.

Thanks for your offer. I prepared simplified scene to let you test, but then realized problem must be somewhere else since I managed to render with motion blur with this simplified scene.

Need to dive back and go trough nodes...

Thanks!

You know what? Deleting old USD render ROP and making new did the trick this time

I noticed that if i render the scene using HQueue instead of rendering directly from Houdini, my motion blur works well, but i have to tell him to write USDs per frame before, quite annoying actually but get the job done