Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Feature Requests => [Max] Resolved Feature Requests => Topic started by: Flavius on 2016-05-30, 16:47:48

Title: Sample Light ONLY via portals
Post by: Flavius on 2016-05-30, 16:47:48

Hi team,

I get a lot of files (CAD mainly) from the clients, (interiors) that have a lot of holes, and small openings in the geometry. For example, holes where the spotlight are, or small opening through the wall panels, or really small gaps between the ceiling and the wallts etc. As Maru explained to me, these kind of, messy geometry increase the noise a lot.
The thing is, I put portals on the main openings, like windows and open doors, but I still have the problem with the gaps, so I need to create extra geometry, sort of light blockers and sometimes it can be really time consuming.

EDIT: For example now I have a huge space (a ship) with a couple spiral staircases that lead outside, both top and bottom , dozens of really small gaps between panels and so on, and I get huge amounts of noise from the env light.

Wouldn't be an ideea to have an option to tell corona ONLY to sample light which comes from/intersect the portal and ignore the rest? So, no portal, no ENV. light at all.

What do you guys think?

Thank you!

Title: Re: Sample Light ONLY via portals
Post by: Ondra on 2016-05-30, 17:42:15

sorry, that is not possible with the way portals are implemented in Corona (basically you would have to disable MIS), and also goes against the Corona portal philosophy as a tool that does not change scene appearance

Title: Re: Sample Light ONLY via portals
Post by: FrostKiwi on 2016-05-30, 22:10:14

Quote from: Ondra on 2016-05-30, 17:42:15

sorry, that is not possible with the way portals are implemented in Corona

Sorry, made me really curious: What does the Portal friction parameter do?

Title: Re: Sample Light ONLY via portals
Post by: Ondra on 2016-05-31, 14:09:18

it changes how much samples are generated from portals, but that is only the explicit sampling - there is also the second part of MIS - implicit sampling, which is not affected by portals at all

Title: Re: Sample Light ONLY via portals
Post by: FrostKiwi on 2016-05-31, 16:08:55

Quote from: Ondra on 2016-05-31, 14:09:18

it changes how much samples are generated from portals, but that is only the explicit sampling - there is also the second part of MIS - implicit sampling, which is not affected by portals at all

ohh thanks, so... in theory, although it goes against corona philosophy, if the only light source is a portal, sampling would be a teeeeny tiiiny bit better if portal friction is 1?

Title: Re: Sample Light ONLY via portals
Post by: Ondra on 2016-05-31, 16:18:41

it depends on situation. If the environment map is HDR, it can actually hurt - because when sampling through a portal, you no longer take into account importance sampling of the HDR map. Or you can have portals placed incorrectly ;)