Slow render and lots of noise

[tallbox]

Hello guys and from me.
I'm new in corona world, but for now i love it.
I'm doing a test scene and it's a big struggle to get decent noise free image for decent render time.
The image below (2 version - raw and after Ps) are fact of 12h render on 3k res. and still has lot's of noise. Light rays here are below 800k which is too less.
I try to rid noise at PS but there are not much that do.
Any suggestions?
G.

PS: my workstation is Xeon 1225v2 @3.20Ghz, 32 Gb ram, SSD, Gtx580 3Gb.
PPS: I've tried to tweak MSI, Sampling balance and all according to HELP info. here. I'm thinking the problem could be in frosted glass, because when i hide it Light rays go higher around 1,6 mil. rays and after 2 passes drop again to 1,1 and so on... (((

[maru]

Hi, have you tried following this to determine whether the noise comes from direct or indirect light?
https://coronarenderer.freshdesk.com/support/solutions/articles/5000516731

[tallbox]

Here are link to archived scene - max 2015.
https://drive.google.com/file/d/0B2MgN82_hVw9eHd1WjA0X1EteDA/view?usp=sharing

[tallbox]

Yes, i've tried to rise sampling balance even to GI 50/ LSM 2 but no success.
At passess seems that indirect lighting has noise.

[tallbox]

And i found maybe a bug.
After render region when you turn back to View from max frame buffer and when you press Render - corona give you Error creating File output. (I did't use that option in this file)
After re-open the scene all is working.

[borisquezadaa]

Could you try to override the wall material?... i have a hunch that maybe the texture format in the wall material could be the issue.
I can't open your scene (dont have max 2015)

[romullus]

And i found maybe a bug.
After render region when you turn back to View from max frame buffer and when you press Render - corona give you Error creating File output. (I did't use that option in this file)
After re-open the scene all is working.

Could you please report it in bugs section. With simple scene where that bug appears attached, if possible.

[PROH]

Have had this error too, but only when having some render elements activated (i.e. Albedo). Seems like Corona defaults to a none existing file path for render elements, in some some rare occasions.

[tallbox]

I tried with deleting all bitmaps on wall and leave it on diffuse colours. Light rays was even lower than previous render.
PS: When i'm doing render regions light rays are much more and stable 1,1 - 1,2 mil.

[maru]

And i found maybe a bug.
After render region when you turn back to View from max frame buffer and when you press Render - corona give you Error creating File output. (I did't use that option in this file)
After re-open the scene all is working.

There is a bug in 3ds max that does this. You need to deactivate render elements or change their path to some existent place. Elements are probably inactive when region-rendering so this pops up when you switch to view. But I'm not completely sure about this so I'll check it and also the scene.

[tallbox]

I will today later

[tallbox]

I found second bug - after adjusting few times gradient map at opacity slot (max 2015) whole max crash. Scene was simple kids room with few objects.

[maru]

There are some things that are causing exceptional noise in this scene:
-reflective caustics - ligths (especially IES lights which may be problematic) facing reflective walls which have wrong materials (example: reflection fresnel ior at 20 or more)
-wrong materials - apart from very reflective walls, also the glass door have too high reflective ior and they had some color in diffuse slot, this is wrong - when creating glass use diffuse level 0 or pure black color, if you want the glass colored either use refraction color or absorption

The scene renders ok-ish when using grey override material so I'm 90% sure slow rendering is because of materials.

Was this scene converted from some other renderer?

[tallbox]

Hello maru,
yes the scene was converted from vray 3.1 scene, that we work in our studio. I just get that scene and used corona converter to test some things. I will check all things that you mention.
Thank you.
I will write later.

[maru]

"Freshly" converted scenes usually need some manual tweaking. Try to make everything as "physically correct" as possible - use correct reflectivity, fresnel values, glossiness, brightness.