"Use Emissive for Static Lighting " not working.

Development Rendering
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1

For some reason I’m unable to use “Use Emissive for Static Lighting” flag in UE4.

I have emissive material, marked “Use Emissive for Static Lighting” in the object lightmass settings, but when I bake the lighting, emissive object does not affect the environment.

It DOES produce postprocess glow, but no static lights.

Am I missing anything?

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I’m interested in the subject because I’ve imported a large scene from another engine, and it uses emissive glow a lot. And i’m unable to replicate the effect in UE4.

2

Have you tried with a static mesh instead of brush as well?

3

Actually… when I set the whole mesh as emissive, it lights up environment. However, when small portions of its texture are emissive, I don’t see any effect. Not sure why.

4

Weird. I’m quite sure i’ve used emissive lighting with multiple material ID’s on 4.9 and they worked fine. But I’ve just tested on 4.11 and it doesnt work as you said. Looks like a bug.

Btw, your reply is sent to moderation for some reason and it wont let me publish it, but Epic should fix it soon.

5

Sigh. I’m a bit to tired to submit a repro to epic games. at the moment.

Single emissive (without texture) worked fine, but with textured ones I’m not getting any lights from anything. Not sure if that’s how it is supposed to work, perhaps emissive light is somehow tied to lightmap resolution and with overly low resolution it is downsampled to nothing or something like that?

6

I’ll do some test later today and let you know, then make a bug report referencing this post.

7

Alright, thanks.

8

So, i did more tests on 4.11 in a new empty level and this time everything worked; single mesh with single material ID, single mesh with multiple material ID’s, and texture as emissive mask on a single material ID. Can you try in a new project, empty level if possible please?

9

You can try a project I had made as a test for another user. You can download it at this link here: [TUTORIALS] Photons Be Free: Mini-tutorials and other curiosities - Community & Industry Discussion - Epic Developer Community Forums

The mesh that I use has two material elements. The back side is the emissive material and the front is a simple base color material.

Have a look and see if that helps you get started. IIRC this project was made in 4.11.

10

I’ll try that, but I’ll need to upgrade the engine first. I have 4.10.1

11

I’ll try that, but I’ll need to upgrade the engine first. My current version is 4.10.1. I’ll try upgrading to 4.10.4 first and see if that changes anything. That’ll probably take (at least) few hours.

12

Alright. I managed to get static lights. Apparently effect was so subtle that emissive surface itself was significantly brighter, meaning that light wasn’t noticeable due to auto-expoure.

However, static light does not appear to bounce at all. Is that intended?

13

Yeah. Emissive generates only direct lighting.

14

Well, that’s a bit disappointing.