Very slow render time

[RED LAB]

Hi everybody,

First i posted for this problem in the section for the V6 built but i tried using the last V5 built and the problem is the same.
I need to render a file of 1.2Go but the render is very slow to reach a level of noise acceptable.

So i checked the load of the proc and it reaches 14%. Now i can get 19% but it still very slow.
What should i check to speed up the render in getting 100 of the proc usage?

Look at the screenshot and the Rays/s, very low.

I added  the Sampling Focus layer to check and it's all white also.

I really need some help on this.
Thanks in advance

[TomG]

Sending in the scene would be best. Failing that, seeing a screen grab of the render settings and an image that gives some idea of what kind of scene this is would be necessary. Sampling Focus being all white - is adaptivity actually enabled?

Also, are you running out of RAM? (doesn't look like it based on the graph - no warnings though?)

[RED LAB]

Here is one of the picture i need to render.
And you'll find to screenshots of the render settings.
I tried with and without adaptive light solver but the Sampling Focus is steel white.

[TomG]

Adaptivity isn't the adaptive light solver, it's Adaptivity (in the Devel Debug settings so it should always be enabled, but then sampling focus should not be all white - or rather, not after 5 passes when adaptivity kicks in)

[TomG]

BTW what is being used to light the scene? (Light set up)

[RED LAB]

For the light setup before i had an HDRI with the new sky but to test i removed it to try Sky+Sun.

Thanks for the adaptivity i forgot to enable the Dev/debug mode but it was on by default.

For now, it still very slow to render

[TomG]

What's generating the interior lighting though, the light set up there?

(BTW, can always send us the scene, saves this kind of questioning ;) - https://corona-renderer.com/upload )

[RED LAB]

For the interior lighting, there is cove light so i did them with light type object / cylinder
Spot lights are IES files.
No light materials in the scene.

[RED LAB]

I did a test all in white and the render has been much faster. So it might comes from textures.
Do you know what i should check on the materials?

[RED LAB]

Here is the Sampling Focus layer

[TomG]

So the sampling focus layer is not all white at all?

This is how it should look, "all white" would mean nothing but solid white. Sampling Focus simply shows where Corona is putting its processing time, white areas getting more attention from the renderer as areas that are harder to sample.

Or do you mean this is the sampling focus with material override, and with materials enabled, the sampling focus is indeed pure white?

[RED LAB]

Hi TomG,

It was all white because i didn't know that i had to wait until pass 5.

But do you know any issue with materials?

[TomG]

Yes, adaptivity only kicks in at pass 5 as mentioned :)

Materials, well, could be anything, can't say without seeing the scene. Albedo is too high. There is bad use of things like opacity and refraction (e.g. converting from another engine sometimes results in plant leaves using refraction, or glass using refraction and transparency, depending on how the original material was set up). etc.

[RED LAB]

Yesterday i tried to upload to you the scene but it stopped. Internet has been a little bit reduced during confinement in France and where i'm based it's low without confinement.... I'm lucky :)

I'm going to try another time right now.

Cheers

[RED LAB]

Hi,

I think the problem has been resolved.
I needed to change the cooling system of my computer and i found that the plastic protection of the cooling system wasn't removed and they put the thermal paste directly on it.
I put the new cooling and now the same render is very fast, the cpu has 100% load. Everything work perfectly.

It seems strange no? Just the cooling system?

[Beanzvision]

Glad to hear this has been resolved. It's amazing how effective thermal paste can be. Please keep us posted in the coming weeks if the situation changes.

[TomG]

Not strange that if not cooled, the CPU would of course throttle and not run at full speed. It is strange that your CPU hasn't destroyed itself if some "plastic" was still on there between it and the cooler. I am not sure who did that, but if that was work you paid for, I would get a full refund.

[RED LAB]

Hi TomG,

That's exactly what i was think off.

Yes i paid a "specialized" company for that.

But i just want to thank you with your effort to help me on that issue.

Cheers

[TomG]

Most welcome! I'm super glad that your CPU is safe, despite what this "specialized" company did (leave them a poor review someplace, as that could be a very expensive mistake, and not one a pro company should be making!)