GPU and CPU rendering - COMPLETELY different.

[hve]

I did some more tests this times with caustics (something I don't use that much) but I must admit that indeed there's quite a bit of difference in both renders

[ivuzem]

I'm in jewellery rendering, and I use caustics all the time. At least I try. And I have also noticed a big difference in caustics on GPU/CPU... Also, Spotlight color map seems to have different positions on GPU vs CPU. I'm thinking it is the similar problem as with caustics, it seems like the HDRI position is different, so that is why we're getting different caustics results.

[hve]

Not sure if this is of any help but I noticed that it's especially an issue with some floor materials in this examples, not all materials have the above issue

[Will Gibbons]

Not sure if this is of any help but I noticed that it's especially an issue with some floor materials in this examples, not all materials have the above issue

Good point. I think this is part of the issue unfortunately. It's the unpredictability that can be problematic. It's a bit easier when the rules are quite rigid, but when there are some things that work and some that don't... it's hard to keep track of what can be relied on and what can't be.

[hve]

Good point. I think this is part of the issue unfortunately. It's the unpredictability that can be problematic. It's a bit easier when the rules are quite rigid, but when there are some things that work and some that don't... it's hard to keep track of what can be relied on and what can't be.

yes indeed Will, now I know of the problem I try to compare more between both renders and there's definitely something going on that's strange

[mafrieger]

since this seems to be an important topic for many "power" users, would be pretty nice to see some comments from Luxion / Keyshot team...
Could they reproduce this?
Is this on the high prio list?

[theShopFloor]

They are completely different algorithms processed in very different ways. In my experience GPU is not even close to CPU when it comes to visual quality. It is great for animations though.
If you build your materials from scratch using only GPU you can get the look you need. It may not be perfect but it can be done.
I purchased a 3090 purely for this purpose but I always end up back on CPU, because it just looks better.

[BoazD]

They are completely different algorithms processed in very different ways. In my experience GPU is not even close to CPU when it comes to visual quality. It is great for animations though.
If you build your materials from scratch using only GPU you can get the look you need. It may not be perfect but it can be done.
I purchased a 3090 purely for this purpose but I always end up back on CPU, because it just looks better.

so basically the marketing claims by Luxion created expectations that drove you to spend a good chunk of change on a high-end GPU that you can rarely utilize. I too am not using the RTX A6000 in my machine as much for rendering because of this reason and I'm sure we're not alone. a lot of people (and businesses) procured expensive hardware and didn't get the results that were promised. this is a very serious issue.

everyone here understands that the algorithms are completely different - I even stated that much in the original post starting this thread. but when a company makes a claim that their software creates physically and optically accurate and realistic true-to-life visuals, using either CPU or GPU interchangeably, then I don't care about the algorithms, I expect a consistent result.
you can solve 3^3 any which way you like but you better reach the same result or else something is broken.
Algorithm 1: 3*3*3
Algorithm 2: 3*(3+3+3)
Algorithm 3: (3^2)*3
I still get 27.
Luxion is making an objective claim. I can't be forgiving about this.

[hve]

Any news on when a new update might be available ? thanks

[mafrieger]

KS11.2 GPU related fixes:
Fixed an issue that caused GPU Geometry Setup to take longer than expected.
Fixed GPU issue for advanced materials with fresnel disabled.
Fixed GPU issue for direct lighting for rough materials using bump.
Fixed the issue where GPU crashes when using GPU mode while using measured materials.
Fixed the issue where the GPU mode is disabled after adding geometry to a scene with geometries included.
Fixed an issue where the Reflection Render Passes in GPU mode give black output.

https://manual.keyshot.com/keyshot11/manual/whats-new/release-notes-2/release-notes-11-2/

=> does this improve some things?

[ddolezal]

After our first tests I can confirm that something definitely happened.
The first scenes we had did not have significant differences, only in "grainyness", but this might be causes by different rendering approaches on CPU and GPU.


From my point this seems to be solved!


Regards,


Dieter

[hve]

For me both renders GPU and CPU do still look quite different in this new update + now I have a crash here each time I try to select a previously saved workspace, all other presets work fine just one workspace preset seem to cause problems here, will investigate more and see how it works on older projets.

[mafrieger]

just did a fast overlay: the objekt seems to be ok, but there is something really strange on the groundplane:

[hve]

Yes indeed the model is ok it's the reflections/caustics that look completely different, I joined the project in my previous message in case.

[mafrieger]

are there only differences between GPU and CPU, and Keyshot versions or does the GPU driver version also influence the appearance?