CPU/thread performance drop with Corona Triplanar

[cgrobo]

I have been having issues with noticable CPU/thread performance drop which seems to be caused by Corona Triplanar Map. I am attaching a graph from HWiNFO. When using corona bitmap without any triplanar maps core usage is up to 100% as expected. When using one triplanar map core usage drops to about 75%. When mixing two or more triplanar maps core usage drops to as low as 55%.

Also attaching graphs from task manager with and without triplanar map.

This issue can only be replicated on more complex geometry, I used a faucet for this test. A simple box won't show this issue. What is even more bizzare is that it happens only when an object is isolated or all the other layers are hidden.

Running on 3ds max 2024, latest Corona daily and 7950x.

[Juraj]

Hmm, concerning, will test myself, as I use Triplanar in like 70perc. of ALL my materials :- ) But my render times are also eternal, so I almost never notice this easily.

[cgrobo]

If you decide to test it, make sure the object is isolated (isolate selection). The drop doesn't seem to occur when rendering a full scene, but who knows if it still affects rendering times.

I usually set up the scene first, then start working on materials. But I started noticing slow performance when working on objects, then all of sudden my fans went real quiet....Turns out I mixed too many triplanar maps.

[cgrobo]

So it seems like the culprit of the drop is caused by blending in triplanar map. Setting the blending amount to 0 results in no drop in performance. Attaching images.

[maru]

Hi, we have received at least one similar report about Triplanar and performance issues and we are investigating with high priority.
If you can share any scene where you are able to reproduce the issue, please do. It can be here or over at our support portal.

cgrobo - support ticket #150018

(Internal ID=1154542295)

[cgrobo]

Hello maru, I think you can easily reproduce this. Create a teapot, add 2+ turbosmooth iterations. It has to be complex geometry. A simple box object won't produce this issue.

Apply a material with gloss 0.8, ior 999, anisotropy 0.4, and c triplanar + c bitmap with some imperfection map plugged into aniosotropic rotation. It's just a simple metal shader. For lighting I'm using studio HDRI from hdri haven.

With Blending set to 1 in triplanar map, there is a significant drop in thread performance. In my case core usage goes down to 65%. With blending set to 0 there is no drop. With 0.5 there is some drop. So it seems like that the perfromance drop is directly correlated with the blending amount.

Let me know how it goes.

[maru]

Thanks, I will try that and let you know about the results!
The reason why we are always asking for scenes is that usually this is the easiest way of reproducing an issue. When creating a scene from scratch, it may happen that we don't enable that one specific option which is causing the issue.

[cgrobo]

I understand. I suggest monitoring Core usage in HWINFO to check performance. As I understand, it is not the same as Core utility and is probably more accurate?

[maru]

I was able to reproduce the issue with the simple teapot scene. Here are my results (12-core Ryzen 3900X):

Blend set to 0
7 255 000 rays/s
CPU usage stays at around ~90%, there is some fluctuation visible, probably related to bucket rendering. 

Blend set to 0.5
5 269 000 rays/s
CPU usage stays at around ~90% again, there are deeper grooves in the graph.

Blend set to 1
3 415 000 rays/s
CPU usage hardly ever gets to 90%.

This is now reported for the dev team to investigate.

(Internal ID=1193978200)

[cgrobo]

Cool Maru, I'm glad you were able to reproduce it.

[Tom]

Hi,

I also have the same issue happening. Interestingly, it happens even when the object is not isolated.

I started this thread: https://forum.corona-renderer.com/index.php?topic=40872

[cgrobo]

Hi,

I also have the same issue happening. Interestingly, it happens even when the object is not isolated.

I started this thread: https://forum.corona-renderer.com/index.php?topic=40872

Until the devs fix this, try setting blending to 0 in corona triplanar.

[Tom]

Until the devs fix this, try setting blending to 0 in corona triplanar.
[/quote]

For now I simply got rid of the triplanar map as it was almost not involved in the final look of my shader, but I will keep your recommendation in mind next time I use it. Thanks.

[rowmanns]

Hi,

We should have a fix for this coming to the daily builds soon :)

We'll let you know when it is out.

Thanks,

Rowan

[clemens_at]

can we also get a hotfix for corona 10?
I'm still on 9 because of this.