Glow from behind blinds

So I’ve just got started in Blender and decided to have a go at a simple bathroom scene, with both a daytime and nighttime rendering. I’ve used an HDRi as the sole source of light in the daytime scene, and then pulled the blind down, set the world light to black and changed all the bulbs in the scene to emissive for the night.

I’m getting a really weird glow however from around the edge of the blind in the nighttime scene. I was wondering if it was just light from the bulbs bouncing between the window and the blind, so changed both so rough matt black materials and it’s still there. I’ve made sure I’ve removed the portal light that was there, the outside is definitely pure black and there’s no other light sources apart from the three bulbs on the walls. I can solve it buy sticking a plane just inside the window, but this seems like a bit of a cheat and I’d rather know what the cause is.

I used the Archmesh tool to make the room, and one thing I have noticed is that if I view from outside in rendered view the room itself still very bright and evenly lit from all sides. Is this part of the reason for the glow, and if so what can I do about it?

Many thanks

hard to know without a screenshot or a blend file (the best would be the blend file)

Here’s a quick render I did of it. What info would be most pertinent to include in a screenshot?


Thanks

what happens if you remove the blind ?
Including settings of the world background in the screenshot may help too

Save as new file, delete everything that doesn’t affect the problem, and share it.

In the process of doing that I found the problem and now feel slightly stupid. When I was doing the daytime scene I must have been fiddling with ambient occlusion (not something I remember doing as tbh I don’t know what it actually does) and forgot to uncheck it when I then started work on the night time scene.

Sorry for wasting everyones time.

Attachments


Glad you solved your issue.
The World Ambient Occlusion is not meant to be used in combination with indirect lighting (i.e. the default settings in Cycles). You would only use it as a compositing layer to multiply with a direct lighting render (for Cycles that would mean setting “Light Paths” to “Direct Light”). This feature is meant to put artistic control over physical accuracy.

Don’t forget to mark the thread as solved by editing the first post, going in advanced mode and selecting “SOLVED” in the dropdown menu (don’t worry, it will become much simpler soon)

Thanks. AO is definitely something I feel I should learn, but I’ll get the basics down first.

I’ll mark the thread solved now.

I sometimes use World AO if I have dark corners in a room illuminated with tiny lamps in combination with big lamps illuminating the main part of the room. In this case you either have to render out separately (I don’t have time) or use a ton of samples (I certainly don’t have time) for the tiny ones to contribute anything but noise. A low factor is required, like 0.1-0.15. Keep in mind that principled shader’s sheen attribute reacts heavily to AO and you may have to turn it down.