night interior render - how to achieve less noise and faster times?

[gabyanz]

Hello to everyone.

I know this is a very repetitive question, But I'm starting to use Corona in production and strongly want to understand well how it works , and how I can achieve "clean" images in reasonable render times.

Please help me if I'm doing someting wrong.

I'm doing an interior retail . Lots of clothes, lots of instanced polys.
HDRI lighting (with a dusk map) and interior plane lights.
some ies here and were (less than 10 in total)

In a 1800px X 1000 image (so not very high resolution) after 3 hours I still have lot of noise, expecially on the floor (quite simple material, glossiness at 0.7, small noise in the reflection slot)

I use ppt + UHD , LSM 4 and GI/AA 32. Internal resolution to 1
I've lowered the MSI from 20 to 15, in order to have a bit less accuracy and less noise, but seems it does not work.

The windows glass are thin...

I am doing something wrong?
It's normal to wait more than 6-7 hours to have a clean mage with this resolution?
My pc specifications are i73820 with 24 gb ram (I know, I need a serious upgrade...)

Thanks in advance for any advice
Gabry

 
The noise is mostly in the direct lighting

[Lucutus]

I would suggest you try to find out what exactly causes your long render times.
Maybe you try to render with a material override to see if some Materials cause the problem.
If your materials are ok i would try to replace the IES Lights with "normal" spotlights.

Im quite sure your troubles are caused by one of these.

in addition it would be good to know how many rays/second and how many rays/sample you have during rendering.

Greetz

Lucutus

[maru]

Yes, it would be best to find the cause of the noise instead of random guesses, but it may not be so easy.
My guesses would be:
-IES lights - how are they made?
-incorrect material setup (too bright, too much reflectivity, wrong fresnel value, etc)
-background - is it simply hdri in environment slot?
-floor material - what does it look like? Did you change "blur" parameter for the noise map?

[gabyanz]

Thanks a lot for your replies...

So my guesses were right, this image is too noisy and slow.

Let me analyze the image.

Rays per second
1444000
(I don't know why, in my previous render were higher, like 1800k)

Rays/sample 85.9

HDRI in the background, Reflection panel (no direct lighting) in some places outside.

IES - CORONA IES

The floor material is quite simple,
see the screen shot.

There is something I could do with the settings ?

[maru]

Reflection panel (no direct lighting) in some places outside.

What is this? How is it made?

[gabyanz]

There are the specifications... i've read that a corona light material with no direct emission could be used as Background

thanks A LOT for your help

gab

[Nekrobul]

Reflection panel (no direct lighting) in some places outside.

What is this? How is it made?

I think that he ment that the enviromet lighting is created with planes using light material.

And one more question 3h render ok, but how many pases? image look like sowhere around 50-70.

And can you show direct, reflect and inderect render elements?

[maru]

Do not use the "disable shadows" option for the plane. Unchecking "emit light" already does this. You can also try with rayswitch material like in this guide:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000515605

Can you try do disable IES profile for the lights and see if it gets better? Or use another IES file, just for a test?

[gabyanz]

The image was 150 passes :/

I've disabled the IES, and modified the background image...
I'm doing another view, and now the rays are 1270000 :/ what's happening?

The indirect pass was almost clear, and also the reflection pass was not that bad...

I'm starting to think that the noise in the reflection in the floor could cause some problem, but I don't know why...

[maru]

If the noise is very fine (small features), it can take a lot of passes for the reflections to refine. But you can check this simply by disabling the noise map. But I doubt this is the issue as the noise is visible in other places too. Doesn't it improve if you disable reflectivity for the floor?

[gabyanz]

Yes, you are right, there is lot of noise everywere.


What do you mean with "disable reflectivity"? put reflection to 0.0?

Now I've started another render (strict deadline, argh).. 30 pass, 50 minutes... lots of noise. humm...

[Nekrobul]

It might sound wierd but it might work.

Try to change light shape on ies lights from sphere to rectangle.

[maru]

What do you mean with "disable reflectivity"? put reflection to 0.0?

Yes, just to test if this isn't causing the noise.

[gabyanz]

Thank you all guys, you saved my life ( oh, almost ;) )

I applied The changes you suggested, and the render times changed suddently...

In less than four hours I've had perfectly noise free images.. With crisp details..

I've not had The time to understand what was The problem, but when The project will be closed I will analyze The files to find what was causing The problem.

Things that I changed
No noise map in The reflection slot in The floor ( bitmap image, instead)
No deselect shadows in background image
Change IEs SHAPE from sphere to rectangle

My opinion is that The IEs SHAPE was The problem, but I have to verify that..

It could be a bug?

Thanks again!
Gaby

[Nekrobul]

Glad we helped you out.