Corona night shots very noise. Solution?

[caioquintana]

Hi guys, this is my first post here.
I started using Corona 1 month ago and everything was going just perfect until I had to make a night shot.

This is my problem:
I have a HDRI to light the scene (env light) and several small corona light to act as artificial light, also IES (corona type) in the garage.
This image took 45 min to render and you can see the lights on the wall and the IES in the garage are very noise.
I had a daylight version of It before that, and It was taking 10 min to get much more clear.
I need to render the final image in 4k, so I`m a little worried about the render time.

What is the best solution for this artificial lights? Can I smooth the GI?
I tried hising the light sample mult to 100, but the render gets very slow and I still get this arttifacts.

I apprecciate your help.

Caio

[caioquintana]

Hey guys,

here is a new test with more PT samples and lights sample mult to 100. All the artificial lights looks better except for the wall lights.
Any ideias? I have to render the final image in a few days.

thanks.

[agentdark45]

Usually when I experience problems like this I'll break my scene down bit by bit and try to figure out what's going on. Seeing as you've got a lot of stuff happening it might be worth while hiding all complex geometry and applying a white material override and see how the noise looks then.

If it's still noisy, hide lights individually. For example, I'd do a test render with just the main geometry with the override material applied with a completely black environment, with only the exterior lights enabled. Then unhide the interior lights / hide the glass window opening geometry so light can come through. Then add back the skylight.

One other problem that I've faced similar to yours is using a combination of max lighting + Corona, it just doesn't work smoothly at the moment. Make sure every light in your scene is a corona light.

[caioquintana]

Thanks, I'll try that tomorrow. I made a quick test using corona sphere light instead of rectangle and it got a little better.
If I raise the PT samples shouldn't I get better results?

[agentdark45]

Not necessarily, the only settings I would change in your situation would be the light samples multiplier (I haven't needed to ever raise this above 32, most times to 6). I would strip your scene down first as described before you start messing with the settings.

[astudio]

just a side note. It's look like early evening but for this case your art. lights are very strong. imho

[caioquintana]

Hey guys thanks for the help.

Just to keep you updated, I rendered the 4k image and it went great. I took way less time than I was expecting (2 hours) and it got rid of the noise.

This is the final image resized.

astudio: Yes I agree, this was not my first lighting suggestion, but the client wanted the natural lights and strong artificial. :/   ... but I appreciate your suggestion.

[gabrielefx]

very nice render!
many people can't' distinguish it from a real shot.
I'm moving my first steps with Corona (always used Vray)

How you resolved the light noise issue? I noticed that Corona doesn't like a mix of big and tiny emitters. If I turn off the big emitters the tiny lights spread well.

regards.