Need some advice from more experienced folks about settings and render times

[Correntes]

Hello,

So this is my first test. Its directly converted from vray to corona.
My objective is to compare render times to see if I can get corona in production pipeline here at the office.

I used PT - HD, standard settings and let it cook for about 3h:13min in a dual xeon. This is what I got... plenty of noise.
3 hours of processing aren't enough to clean a scene of this type ?

Mind you that this is an optimal interior (the back and side of the room are windows) and its lit only with a HDRI.

Hope I can get some insights about it.


Thanks

[rafpug]

Hello Correntes

Can you describe the combination of lights that you used for the scene?

Thanks
Raf

[Correntes]

Hello rafpug

Sure...

I only used hdri on max environment slot.

Thanks

[Correntes]

So I did a region test to see if how many passes are needed to clean that wall.

I let it run for about +- 900 passes to get acceptable noise levels. Well that would mean about +- 18h render...

[Ondra]

something is definitely wrong. Are you using default settings (PT samples, lights multiplier)? Can you printscreen the stats window (you activate in in VFB) after some time (~10 passes) when rendering?

[Correntes]

Hello Keymaster,

I tried corona in another project and had similar behaviour,  I tough that was due the fact that the other project have smaller windows.


Here it is a screen-shot of the settings from this current project.

Settings for what I know, are the default ones.



thanks

[Juraj]

What HDRi do you use ? High in contrast ? Big resolution ?

[Correntes]

Hello Juraj,

Its one HDRI from Peter Guthrie.

I'm using it with gamma boosted to 0.75. And I'm running it from a colorcorrection map and vrayhdri map.
Due this setup never gave me problems in the past I never thought that could be cause.

I'll guess that I can start by trying using a cleaner solution.


I will report tomorrow with my findings.


Mean while if you find something awkward with the settings please alert me.


Thanks

[Correntes]

Hello,

I tried to swap hdri for coronasky lightning went worse as expected... similar behaviour maybe a little less grainy.

Then I turned off the glass (a box with a material applied with refraction onesided (box)) i got acceptable noise levels by the 327 pass... That would mean more or less a render of 6 hours


Better but I think that for this kind of scene the render times are still to high and with allot of conditions (glass turned off, coronasky)

[Ludvik Koutny]

Hello,

I tried to swap hdri for coronasky lightning went worse as expected... similar behaviour maybe a little less grainy.

Then I turned off the glass (a box with a material applied with refraction onesided (box)) i got acceptable noise levels by the 327 pass... That would mean more or less a render of 6 hours


Better but I think that for this kind of scene the render times are still to high and with allot of conditions (glass turned off, coronasky)

There is no reason to do any compromises when it comes to the way scene looks. So i definitely would not replace HDRI with corona daylight. Does not make any sense. Changing the look of your scene completely is not a proper way of optimizing scene performance.

Problem in your scene is probably glass. And it has been mentioned at least 100 times already. For glass in windows, use either hybrid refraction mode, if you glass geometry has any thickness. Or twosided mode, if your glass are just single planes. If you leave refraction mode set to solid, then anything behind the glass (inside of the room) is computed as a caustics, not direct lighting.

[Polymax]

Can you post your scene? I will test it!

[Correntes]

Ahrg... I already had saw the" hybrid refraction mode" thing here in some threats and I completely mistaken for onesided in this scene  =|

[Ludvik Koutny]

Ahrg... I already had saw the" hybrid refraction mode" thing here in some threats and I completely mistaken for onesided in this scene  =|

Hybrid and twosided modes are fast ones. Solid is one with caustics. If you use hybrid or twosided and still have slow rendertimes, then there will be some other problem in your scene :)

[Correntes]

Can you post your scene? I will test it!

Hello Polymax, thank you but unfortunately I can't post the scene.


The glass in hybrid certainly helped thanks for the reminder Rawalanche .

3 hours render, PT-HD standard settings, noise is somewhat acceptable, not perfect but acceptable. Can it be optimized ?


ANother question:

Corona framebuffer is 32 bits right ? I saved the image in exr and I felt that in a way I didn't got that dynamic range that I usually do.

It could be for the position of hdri but when I played with curves I couldn't boost mids like usually.
I didn't compressed highlights in corona post processing  to keep max color info but I used exposure compensation to correctly expose the scene.

Thanks

[cecofuli]

For 3500px render  (A4 300 DPI) usually I render in  7-10 hours...   (with I7 970  @ 4 Ghz)