Light Portals Do Not Really Work

[Dustmote]

…or then the 20 samples count is too low for the house. When I did the exercises with Mike, I got a visible difference in graininess when using portals but not so much with the house. Then I remembered that I downloaded and installed that Filmic… something that everyone is recommending and that I was supposed to have a brighter sun with that. I used nodes to brighten the sky.

Window, dimmer sun, no portals.

Window, brighter sun, no portals

Window, brighter sun, with portals

I don’t know… I think it looks worse with the brighter sun. Messier and kind of unrealistic, since the windows are so small. Just for reference, dimmer sun with portals.

I would still use light portals, because they worked with the cube test.

[FedPete]

Light portals only work when you use environmental light.
Because light comes from all directions (360), so a light portal will help the render to discard light rays.
If you use a lamp, this is not needed. The location of the lamp is known. So light portals are not needed (do not work).

[Dustmote]

Hi Pete

I do have the environmental light there. That is the white color of the… is it skybox? And the lamp there, well, I understood that you create light portals by choosing area light and then ticking the “portal” box. That’s what I did, anyway, so that “lamp” there is not really a lamp.

I think that the room is just too dark? Those windows are kind of small. Maybe I just can’t expect better froma dark corner with too tiny windows for a light source.

[FedPete]

Hi, to be honest I also had my share of problems with portals.

I believe it’s only reacting on this one (but not sure).

[Dustmote]

Your settings seem to be the same as mine. Maybe you already had enough light? Mike did mention that the portals don’t necessarily always help.