(open)[HOU-4254]Attributes with motion blur on not working (GPU)

[tobiasroesli]

Hi,

looks like there's a bug with attributes and motion blur in the latest nightly in GPU mode...


Houdini 19.5 build 805
V-Ray for Houdini number:22702 hash:cc9ab74 from 01 May 2024 01:48
V-Ray Core 6.20.09 [e5b23c59] from 29 Apr 2024

[tobiasroesli]

When I put a pack sop before the material it works in gpu mode. But why is it working in cpu without?

[viktor_angelov]

Thank you for sharing tobiasroesli I will double-check and come back to you

[viktor_angelov]

Using Pack SOP works for me as well. I would encourage you to use it.

You said "in the latest nightly build" - Do you mean that before that you have seen it work differently?

[tobiasroesli]

Hi viktor_angelov yeah I use Alembics most of the time. I just realized it when I took a quick test on something. I know that when you use Displacement you must use packed geometry but with some normal geo and attributes it should work without or not? Or do you also must have packed geometry with attributs?

You said "in the latest nightly build" - Do you mean that before that you have seen it work differently?

I accualy dont know, like I said, I use alembics usually.

[frame48]

Using Pack SOP works for me as well. I would encourage you to use it.

You said "in the latest nightly build" - Do you mean that before that you have seen it work differently?

Using the pack sop has mixed results - in our scene this solution is not working. The existence of a v attribute (or motion blur being turned on) completely obliterates any attributes used in a shader, regardless of being packed or not. This is making GPU in houdini unusable at this time.

[frame48]

Here is a basic stripped down scene showcasing the issue - when packed with motion blur enabled you will see the noise pattern disappear in render. When you disable motion blur (packed or unpacked) the attribute is now accessible in the shader. Please keep us updated if there is a hotfix for this as it is such a fundamental feature.

[tobiasroesli]

frame48 yeah, cpu seams to work fine.

I had so much trouble with the GPU engine in the last project. I had days for finding workarounds and reporting bugs. Nobody paid me something for that and in the end I had to worry about even holding the deadline because of it.

switching to CPU is no option for me. Im a one man show and can't afford a proper CPU renderfarm. My last project took me 10 Day to render on OPTIX with 2x 4090 and 1x 3090. I could not imagine to render that with CPU's

[frame48]

Yeah we are in a holding pattern with this bug, if anyone from Chaos can recreate and confirm it's not working as intended please let us know. Thanks so much.

[viktor_angelov]

Thank you for sharing! We are currently looking into this. Will contact you if we have more information on the matter.

[viktor_angelov]

Thanks to everyone how took part in this! We have investigated the matter and the issue has been logged into our system for future resolution [HOU-4254]

We will make sure to contact you once the situation has been successfully resolved.

[frame48]

Thanks to everyone how took part in this! We have investigated the matter and the issue has been logged into our system for future resolution [HOU-4254]

We will make sure to contact you once the situation has been successfully resolved.

Thanks Viktor - really appreciate the reply. Do you all have an estimated time on fixing this bug? GPU is currently unusable in production without access to attributes.

[viktor_angelov]

Hi frame48 As a company policy we are unable to share any information regarding ETAs for future builds. Thank you for understanding.

[frame48]

Hi frame48 As a company policy we are unable to share any information regarding ETAs for future builds. Thank you for understanding.

Understood, thanks Viktor. I just received an email that the ticket was closed and completed - curious if this in a new nightly?

[viktor_angelov]

Hi frame48 The ticket has closed automatically because 10days have passed. However, this does not mean that the fix has been implemented in the builds yet. We will make sure to contact you once it does.