GPU Rendering Slower Than Realtime - NVidia RTX 3090 ti

#21

I think that’s really interesting information for KS! Since you’re in GPU mode I would say the existence of NURBS shouldn’t impact your render times at all. So I think it’s even more strange not having those model sets selected having such an impact on the render time.

I don’t use NURBS models that often, but I wonder if that has caused me some issues in the past as well.

@dries.vervoort and @jan.simon.1 sorry to tag you guys but I think the findings of Pierre are really worth some investigation looking at the difference in render times.

#22

Hi,

Thanks for tagging developers.

I’ve removed all NURBS in my file but I still get speed reduction.
I saved my material and make a new file by imported all my parts without nurbs, and rebuild my animation opening with same lights and material. It seems to not have speed reduction.

I’ll continue to rebuild my scene and launch rendering step after step to figure when rendering time drops.

I’m guessing if it could be something linked to huge amount of datas duplicated/deleted in the file and multiple incremental saves that could corrupte the file, but I have some doubt.

Best

EDIT : After rebuilding my file, it seems that is still an issue with the planar lights. I’ve added my planar light to my scene with curve powered material and that makes the sample rate drop.
I added a standard plane to see if an area light makes same behaviour and I copy paste the planar light material (to keep the power curve) to the plane, then make the render and sample rate came back to normal. Maybe something linked to the ‘geometry’ of the ‘planar light’ object.

EDIT 2 : I should miss something, use planar with planar light material doesn’t change speed reduction but area light with curve animation for power works instead of curve powered planar light.

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#23

@oscar.rottink is right in his reply below this one - my file does have Nurbs data, but none of the objects are set to “render nurbs.”

#24

Thank you for all of your investigation into this, and thanks to @oscar.rottink as well! I’ve moved on from the issue due to production schedules, etc., but for me it was never resolved. KS support wanted my scene file, but the need for an NDA complicates this.

I remember deleting a model set at one point and gaining the speed back a bit. There was nothing special or notable about the model set - it was just not needed. My renders were still slower than realtime, but not quite as slow. I could not find a link anywhere as to the cause.

I have some big animations projects coming up soon and I am dreading it a bit. And now you mention a problem with planar lights. Sigh.

#25

Hi @dan.spore,

Pierre put also a topic here:

[BUG] GPU, NURBS & Motion blur - For Beta Testers - Luminaries

If you’ve not seen it, it’s interesting since he found out that actually getting rid of the Nurbs seems to help a lot. Of course that’s not an actual solution but they are working on it. At least it will hopefully reduce the render times compared to the real time window.

He also found out that even inactive model sets still impacted the render times if there were Nurbs present. His suggestion to import models without any Nurbs is I think the best way for now to prevent you from getting rid of Nurbs afterwards.

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#26

Thanks for pointing me to this, @oscar.rottink!