rays/s actual

[jarekhell1]

Hello,
i need help. This is my first time when I use a corona, before I worked on vray. I converted the scene from vray to corona, I set the parameters after the trials and errors and I have two questions.
1) what is correct, path tracing + uhd or path tracing 2x for exteriors renders ?
2) how many rays/s actual should i have during rendering ?
3) how can i optimize render setup to speed up render time and achieve good quality ?
Render time estimated 6h, in vray 2h40min, over 2x longer, why ?
Regards ;)

[romullus]

Hi,
Here's some answers from me.

1. you can use either. There's no single correct answer. If you don't render animation, then there's little to no reasons to not use UHD. In your scene it took only 2 and a half minutes to calculate, but can increase noise removal quite significantly. Its success rate i over 40%, which is good result for such scene.

2. it depends on your CPU and on scene complexity. It will vary wildly from scene to scene and even from shot to shot. But in any case with decent CPU, it should be in range of millions. Your scene shows unusually low r/s, unless you're rendering with very low spec machine, this scene needs to be investigated for problems. Take a look at this article and see if you can find a culprit of slow rendering: https://coronarenderer.freshdesk.com/support/solutions/articles/5000501981-rays-per-second-too-low

3. leave render setup at default and focus your attention at the scene itself. Maybe there are too complex or badly constructed materials, maybe some problems with geometry, or maybe your PC is running out of RAM. This scene shouldn't take 6 hours to render, it shouldn't even take 3 hours. Look at my link above and try to find what's causing slow down. If you don't manage to find it on your own, you can submit support ticket and friendly Corona Team will gladly help you. https://coronarenderer.freshdesk.com/support/tickets/new

[jarekhell1]

Thanks for response. I'm using ryzen 1700x 8x3,4GHz, 32gb ram. When rendering, CPU is used in 98% and ram 50%.
I'll try make some new simple scene, make two versions with different materials: vray and corona, and try both engines. Maybe in this scene is mistake.

[romullus]

Ryzen 1700x should render like a breeze. Don't abandon that scene, try to find a problem like i suggested or ask support to help you.

[PROH]

Hi. This could be caused by the materials.

When converting from VRay I've found that many people uses refraction in foliage materials. That's not a good idea. If that's the case, then turn refraction off and use translucency instead (if needed).

Another thing to check is displacement.

Hope it helps

[jarekhell1]

I removed trees scattering with forest pack and scene work well.

[actrask]

It's good practice to take a look at the materials after they've been through the corona converter. Once while working on a very close shot, I merged in a corona converted asset and it took forever to render. Turned out there was an AO node being used for a mask that was being multiplied on top of itself about 50 times.

PROH makes a good point to check the translucency and displacement. Those have tripped me up after a conversion.

And Romullus makes a good point to stop futzing with the render settings and just focus on the scene. Coming from vray myself, I was very guilty of that. With vray you seem to always have to wear a TD hat. That's not necessary with Corona, you can just art.

[jarekhell1]

Hmm, i see when i put some tree models to scene (correct materials), my rays / s are falling down heavily, and RAM use falling under 50% (about 47%). It's ok or something is wrong with tree models ? (high poly from cg axis).

EDIT: not 47 but only 27% RAM is in use. Why only 27% ?

[romullus]

Why only 27% ?

Why does that bother you? The less, the better, contrary to CPU usage :]

[PROH]

Just to understand you correctly. Are you saying that RAM usage is falling when you unhide the trees? Or is it just the overall RAM usage that is lowered after you corrected the materials?

[jarekhell1]

Hmm, I saw something wrong, I just tested different tree and material settings and RAM usage is always around 50%. Is it possible to somehow increase the use of RAM and thereby speed up the render, does not it work that way?
One more question in Corona Frame Buffer colors of the render look great, but when I write to 16bit tiff, these colors become slightly faded and the render is slightly brighter (I overwrite the gamma up to 2.2 when writing). Is it possible to save a render without losing colors so that it can be modified in PS?

[TomG]

On RAM usage, Corona will use as much as it needs, and there is not a) any way to "use more RAM" and b) no benefit to doing so even if there was a way to force it :)

[nilyildiz]

Merhaba,
bir konu hakkında yardımınıza ihtiyacım var 2 farklı bilgisayarda aynı sahne ve aynı acının renderını aldım fakat 3ds max performans kısmındaki rays değeri iki bilgisayarda da çok farklı değerde oldu. 1. bilgisayarın özellikleri AMD RYZEN 7 5800X-8 CORE PROCESSOR, 3801 Mhz 8 çekirdek 16 mantıksal işlemci. bi bilgisayarın 3ds max performans rays değeri 6.000.000 civarında oldu. 2. bilgisayarın özellikleri 12. nesil intel i7 12700f 32 ram 64bit işlemci sistemi 3600ti ekran kartı. bu bilgisayarın 3ds max performans rays değeri 1.300.000 civarı oldu.
ben 2. bilgisayarın sahibiyim ve iyi özelliklere sahip olmama rağmen performans değerinin düşük olmasını anlayamıyorum. bana yardımcı olursanız sevinirim.

[TomG]

English only on the forums, please.