GPU and CPU rendering - COMPLETELY different.

[hve]

Ok thanks for me that's not the case, it's just different and that's absolutely not an issue for me

[BoazD]

Ok thanks for me that's not the case, it's just different and that's absolutely not an issue for me

I think what's "better" depends on the use-case... for me gpu renderings always flirted with the uncanny valley and just looked like really good computer graphics, less convincing in terms of realism. over time the lines are getting ever more blurred but i think the fundamentals are the same.

if you're rendering something with a very strong anchor in reality and you're trying get the utmost accuracy and make your rendering indistinguishable from real life - then cpu is the right tool for the job.

for marketing/promotional materials "for illustration purposes only" where you may want to have visuals that are "better than real life" - gpu can work for you.

I was just hoping it wouldn't be like that in Keyshot, I was hoping to get the same results just with more accessible hardware..

[TGS808]

I've seen what I would call very good results from GPU renderers. Both out of KeyShot and other render engines. That said, in pretty much every conversation/forum posting I can recall about GPU renderers all any one ever talks about is how fast it is and how quickly their image got finished. No one ever talks about how good it is. Speed seems to be the main factor the majority of people are interested in when it comes to GPU. And yes, we'd all like things faster but not at the cost of quality.

[richardfunnell]

Throwing my two cents in, because this is as great discussion.

At this point I'm using 98%+ GPU rendering for almost every project, and have for the past year or so. For animations, it's been a game changer (albeit a buggy, not super reliable game changer).
I agree that CPU has an edge in terms of realism, but even with a 64 core Threadripper, I can iterate much faster on the GPU, which is mind boggling. It's not perfect, but I budget time for a little bit of Photoshop work, and most clients wouldn't know the difference. I can leverage the GPU for rendering lots of images + passes at high resolution, and take advantage of a robust post-processing workflow to take it from 90% to 100%, compared to CPU getting me to 96%.

I agree that "better" definitely depends on the use case. For me, faster can ultimately be better, because it means I can get more revisions in. My goal, however, isn't the same as many of you who are trying to achieve total realism, or to match an existing library of renderings. It's also crazy to think that I haven't rendered on my Threadripper in over a year, it's basically collecting dust. Not what I would have expected when I shelled out $5K for it three years ago.

It's unfortunate that I can't leverage both, and if there was a deal breaking issue with GPU rendering, I wouldn't be able to match the output using my CPU as a backup. To a previous point, it's an "all in" mentality.

[ddolezal]

I find the discussion interesting - unfortunately, in some cases the differences in the results are even more pronounced than in the example given by the Starter of the thread. We currently see that the GPU simply treats materials and reflections different than the CPU - in the CPU renderings we see effects that were simply not there during scene setup (done in GPU mode).


In the example below you see that in CPU-Mode reflections of the lightning is honored and shadows look completely different than in GPU mode.

[mafrieger]

I find the discussion interesting - unfortunately, in some cases the differences in the results are even more pronounced than in the example given by the Starter of the thread. We currently see that the GPU simply treats materials and reflections different than the CPU - in the CPU renderings we see effects that were simply not there during scene setup (done in GPU mode).

In the example below you see that in CPU-Mode reflections of the lightning is honored and shadows look completely different than in GPU mode.

yes, these differences are pretty extreme and not only a matter of taste.
just a question, are you using
- latest KS Version (11.1.0.46
from  2022.03.21) and
- latest Nvidia driver (512.59  from 2022.4.26)
?

[TGS808]

In the CPU renderings we see effects that were simply not there during scene setup (done in GPU mode).

Based on what we've known (pretty much) since GPU rendering was introduced to KS, this is not a surprise. If you do your set up using the GPU, you should be planning for a final render using the GPU. If you do your set up using CPU, the CPU needs to be used for final output. Mix and match doesn't work.

[mafrieger]

Mix and match doesn't work.

yeah I understand that this was the case how it works at the beginning of introducing GPU-Mode in KS9 two years ago.

But even at this point of time, Luxion claims in their manual to KS9:

You may toggle between GPU and CPU as needed.

Limitations

The output of GPU mode matches what you get with traditional CPU rendering in KeyShot, with only a few limitations.

• Cutaway material: .../li]
  
  • 
    Gem material: ...
    
  • 
    NURBS:  ...
    
  • 
    Legacy textures:  ...
    
  • 
    Curve geometry: ...
    
  • 
    ZSpheres:  ...
    
  • 
    Volume caustics: ...
    
  
  Most of these limitations will trigger a warning icon , which will appear in the top right corner of the Real-time View. Click the icon for more information about what parts of the scene are impacted and by what.

https://luxion.atlassian.net/wiki/spaces/K9M/pages/1139015787/GPU+Mode

=> so with this description, with my understanding, both modes should be interchange able (already in KS9, yes we all know this was hardly case...but ok it was a great start!!)

But in April 2022 with KS11.1:
If the modes are not interchangeable, it looks like a bug to me and should be reported to Keyshot.
[/list]

[TGS808]

But even at this point of time, Luxion claims in their manual to KS9:

You may toggle between GPU and CPU as needed.

I haven't read the manual cover to cover and so, haven't seen that. They either need to remove that from the manual or make it true.

[mafrieger]

Just looked into it:

It's an even enforced claim in KS11
and in addition, named limitations have been reduced:

The output of GPU mode matches what you get with traditional CPU rendering in KeyShot, with only a few limitations.

• NURBS:...
• Legacy textures: ...
• Curve geometry: ...
• ZSpheres: ...

https://manual.keyshot.com/keyshot11/manual/render-4/gpu-mode/

=> so filing a bug-report for every not matching topic should be very reasonable.
Thanks for everyone doing this, because it makes KS better!!!

[hve]

I think what's "better" depends on the use-case... for me gpu renderings always flirted with the uncanny valley and just looked like really good computer graphics, less convincing in terms of realism. over time the lines are getting ever more blurred but i think the fundamentals are the same.
if you're rendering something with a very strong anchor in reality and you're trying get the utmost accuracy and make your rendering indistinguishable from real life - then cpu is the right tool for the job.
for marketing/promotional materials "for illustration purposes only" where you may want to have visuals that are "better than real life" - gpu can work for you.
I was just hoping it wouldn't be like that in Keyshot, I was hoping to get the same results just with more accessible hardware..

Maybe I should change my eyes then, again I see differences but like in other renders (for example try Redshift in C4D vs Physical render and you'll see it's completely different way way different but Redshift is an industry standard like Octane and Arnold and it's a GPU (and now also CPU in Cinema 4D R26) ... again all ok for me but I think he GPU is totally ok for me and is the future for rendering for most of us

[hve]

I find the discussion interesting - unfortunately, in some cases the differences in the results are even more pronounced than in the example given by the Starter of the thread. We currently see that the GPU simply treats materials and reflections different than the CPU - in the CPU renderings we see effects that were simply not there during scene setup (done in GPU mode).
In the example below you see that in CPU-Mode reflections of the lightning is honored and shadows look completely different than in GPU mode.

Strange indeed, some reflections are completely missing, didn't see this in my latest renders but I switched completely to GPU now so I don't compare anymore

[BoazD]

I think what's "better" depends on the use-case... for me gpu renderings always flirted with the uncanny valley and just looked like really good computer graphics, less convincing in terms of realism. over time the lines are getting ever more blurred but i think the fundamentals are the same.
if you're rendering something with a very strong anchor in reality and you're trying get the utmost accuracy and make your rendering indistinguishable from real life - then cpu is the right tool for the job.
for marketing/promotional materials "for illustration purposes only" where you may want to have visuals that are "better than real life" - gpu can work for you.
I was just hoping it wouldn't be like that in Keyshot, I was hoping to get the same results just with more accessible hardware..

Maybe I should change my eyes then, again I see differences but like in other renders (for example try Redshift in C4D vs Physical render and you'll see it's completely different way way different but Redshift is an industry standard like Octane and Arnold and it's a GPU (and now also CPU in Cinema 4D R26) ... again all ok for me but I think he GPU is totally ok for me and is the future for rendering for most of us

I'm not saying GPU renders can't look good, or even great... and I acknowledged that over time as the tech improved the lines have blurred between the potential of gpu and cpu, that's just how I've seen things come about.. speaking of Keyshot specifically - i still think cpu is way more convincing in terms of realism and accuracy. again, that isn't to say you can't reach pleasing results on gpu, it just depends what you're after.
I mean, we know keyshot was exclusively a cpu renderer until like 5 minutes ago (exaggeration) and it makes total sense that all the efforts until then went into getting the best results on cpu, and only recently they've been making tweaks to make it work as best they can on gpu. in this context it's unreasonable to expect similar results from both render engines, but then the Luxion marketing department got to work and completely oversold this feature which leads (rightfully so) to user disapointment at best and dare I say a demonstrable case of false advertising (allegedly, not a lawyer, not legal advice or accusation, don't sue me).

[TGS808]

Maybe I should change my eyes then, again I see differences but like in other renders (for example try Redshift in C4D vs Physical render and you'll see it's completely different way way different but Redshift is an industry standard like Octane and Arnold and it's a GPU (and now also CPU in Cinema 4D R26) ... again all ok for me but I think he GPU is totally ok for me and is the future for rendering for most of us

You like the GPU and get good results from it. We all understand that. You don't have to keep trying to convince us. GPU rendering is definitely not the future of rendering for me (and probably a lot of others) no matter what you think but that's ok. If you're not an Nvidia stockholder, you don't have to sell us on it. Enjoy rendering with your GPU and keep enjoying the results.

[ddolezal]

yes, these differences are pretty extreme and not only a matter of taste.
just a question, are you using
- latest KS Version (11.1.0.46
from  2022.03.21) and
- latest Nvidia driver (512.59  from 2022.4.26)
?

Yes to both questions.
We use 11.1.0.46 and the latest Production driver for our 3080 TI, Which is 511.26.


From our point of view it is a bug - as not only the reflections, but also the shadow areas in the lower left part of the tray look completely different.
It seems that some material properties are simply not honored by the GPU during rendering.


Regards,
Dieter