Author Topic: Extremely Slow render times  (Read 3142 times)

2021-12-30, 16:28:13

Armand Rudy

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Hi everyone,

I recently invested in a New Machine thinking it would help me work with Corona smoothly.
But I noticed some very slow render times on my recent render a very basic scene with a little amount of vegetation.
I have 55 trees and 500 grass models scatterred. The render is taking 10 hours with Cinema 4d and corona 7
Most textures used are between 6k and 4k.
I instanced everything except the house model. Render resolution 2560x1600. HDRI lighting only.

My Computer specs : Ryzen 7 3700x
                              32 GB RAM
                              RTX 3060
Before I jump into a GPU renderer. I wanted to see if the issue is coming from my ignorance or maybe Corona is specifically dedicated to rich 3d artists and enthusiasts who can only afford 38 cores CPU

The render and render settings are attached below

Thanks

2021-12-30, 17:01:35
Reply #1

CJRenders

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I know you said you switched to a new computer hoping for faster speeds, but have you recently updated c4d? There were a lot of fixes in the latest version

2021-12-30, 17:05:02
Reply #2

Armand Rudy

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Sorry I didn't know, I am currently using S24, so if I update to S25 will my problem be solved? I thought Corona render was a third party render engine.
How can Cinema 4D cause it to render slow ?
Excuse my ignorance, I am not too geeky.

2021-12-30, 17:13:22
Reply #3

CJRenders

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While corona is the renderer, c4d is the program that corona runs on. So is c4d has flaws it will most likely effect any engine. However, some people have preferences on what version of c4d they use. if you update to 25 the UI will be changed and might effect your workflow for a while. Personally, I always use the most recent version and just adapt to the UI.

 There could be numerous things causing this issue for you but my first thought would be to clean up temporary files, update drivers and windows if available, and update c4d.

2021-12-30, 17:18:57
Reply #4

Armand Rudy

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Thank you, I will do that...

2021-12-30, 19:12:58
Reply #5

romullus

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I wonder why did you set render pass limit so high? 50-100 passes should be more than enough for your scene, especially since you also use denoiser. Render time would be a fraction from what you get now.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2021-12-30, 19:15:48
Reply #6

Armand Rudy

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Hi, I tried 100 passes but I still got noises in the shadow under the balcony... I don't know why... I will try again... But for this scene, my computer is running out of ram, maybe this could also be the issue.

I am still banging my head trying to understand what's eating the ram away so much...

2021-12-30, 19:59:07
Reply #7

CJRenders

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32G is doable but not ideal. I would recommend 64 as a bare minimum tbh. BUT if you were able to share the scene itself we could take a further look

2021-12-30, 20:05:51
Reply #8

Armand Rudy

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That's the issue, we will always need more ram, I heard of people running out of 128GB of ram. Looks like it's not an exact science. It may be one of the limitation of CPU renders. I am not too geeky but from what I have read online, GPU renderer like redshift can handle millions of trees with an 8gb GPU.

The issue is the ease of use and it's going to cost additional money, I am sure a lot must be done before getting accurate renders in redshift, but I am looking into it as well, If I can't manage to render this small scene on a CPU render, I must at least try GPU.

I have already invested on this setup and my next upgrade must be justified by more income from clients, so I am afraid adding or upgrading RAM is out of the question for now.

The scene is 700MB plus the texture folder it's around 1.5GB. Should I send it via wetransfer?

2021-12-30, 20:10:04
Reply #9

BigAl3D

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A low-quality HDR can produce bad shadows and noise. Also, if your system is running out of RAM it will swap with the hard drive which is dramatically slower unless you have super fast SSD. Also consider the resolution of your materials. In my opinion, only the trees near the camera could use such high resolution textures. It's just overkill unless you are rendering different shots in the scene then that makes sense. C4D loads all of those 4k and 6k images into RAM. I don't know the sizes you have, but I can imaging each of them could be hundreds of MB or more for each one. That CPU is not world-shattering speed-wise. I see online it's does 12195 in the Cinebench r23 multi-core test. For example, my 5-year old iMac Pro comes in around 16737 in multi-core. Either one is nothing compared to Threadripper 64, but then again, that $4,000 USD just for the CPU. I get it.

What I love about Corona is you can still get decent speed on older CPUs. I think it's a matter of learning to adjust your scene for best optimization.

Do a quick test. Change your sky to Physical Sky (no HDR). Maybe add a Sun to match your shadows. Set your settings to match mine to override all materials and render a test. Try 100 passes or use the Noise Level Limit to 5 and hit render. See if you still have noise. If you do NOT, then I suspect it's the HDR creating the noise.

Sorry, I'm rambling a bit. Post back your results. Good luck.

Another thought. If it really is such a small area giving you trouble, consider rendering just that area with more passes, then just paste them together.
« Last Edit: 2021-12-30, 20:16:01 by BigAl3D »

2021-12-30, 20:25:15
Reply #10

Armand Rudy

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Thank you, I will try your settings, I have before using the HDRI, tried the corona sun, but I wasn't getting the same quality of lighting than the HDRI.

The HDRI is from HDRI-skies, it weighs 500MB is it low quality or High quality?

For the trees, I have to render 8 differents angles and all of them must have high quality trees. For the textures what do you recommend? I am using some 6k and 4k textures for crisp renders, is there a way to reduce their resolution?

Attached below is a screenshot of the corona sun, the light is not reaching all the dead angles, and it's too dark.
it maybe me who don't understand how to use corona sun, but the trees are blocking the sun, the noise will seem worse in my opinion.
« Last Edit: 2021-12-30, 20:31:55 by Armand Rudy »

2021-12-30, 20:41:51
Reply #11

BigAl3D

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Are you using the  Corona Sky AND the Sun? The sky will provide light from all directions. Can we assume you are also using a Corona Camera? You may need to adjust settings for exposure.

2021-12-30, 20:57:07
Reply #12

romullus

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For the trees, I have to render 8 differents angles and all of them must have high quality trees. For the textures what do you recommend? I am using some 6k and 4k textures for crisp renders, is there a way to reduce their resolution?

Single 4K texture will take 50 MB of RAM. 6K texture will need double of that. That's assuming that your textures are 8 bit. 16 bit texture will need twice as much. Lots of high-res textures is the quickest way to fill your RAM.
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2021-12-30, 20:59:43
Reply #13

Armand Rudy

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I have opened each material, I am using only 5 materials with 4k and 6k textures.  Maybe the specular, glossiness, displacement from the 5 materials are making the scene slow...

I will try and find 2k versions of these textures and replace them

2021-12-30, 21:01:25
Reply #14

Armand Rudy

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Are you using the  Corona Sky AND the Sun? The sky will provide light from all directions. Can we assume you are also using a Corona Camera? You may need to adjust settings for exposure.

You were right I adjusted the settings like you said, no hdri, just a corona sun and sky. Now the light is illuminating the whole scene, let's see if the render time is reduced.
« Last Edit: 2021-12-30, 23:38:34 by Armand Rudy »