Can emissive materials reflect properly like lights?

I’m working on a scene containing LED strips just above the ground underneath a wall near a plinth.
For some reason the emissive light coming from the mesh doesn’t get reflected like a proper light would.

This is with a light, basically what I want to accomplish with the emissive light instead.

This is with the emissive light

Only when I get underneath is see some reflections

Is this a limitation of the engine or is it some option I’m missing on the emissive material?

The emissive coming from your mesh isn’t actually lighting up the environment. You’ll need to use an extended light source to do that. IIRC there is a way to “activate” the emissive material and allow it to light up the environment, but I don’t remember where I read about it. A quick search should yield the answer. =)

You can indeed use emissive materials as static lights, the issues here is not the lighting but the reflection of the emissive material that isn’t visible :slight_smile:

You likely either don’t have “use emissive for static lighting” checked on the strip light static mesh or don’t have emission set very high (multiply the value going into “Emissive” in the material to bump it up a bit).

Additionally, the reflection of the strip light you’re seeing on the floor disappears when you’re stood up because it’s in screen space: if you can’t see the object being reflected, it won’t produce a reflection. You could probably mitigate this by putting a reflection capture actor down between the strip light and the floor so you get a pre-rendered reflection when it’s out of sight.

The reflections are Screen Space Reflections so it can’t reflect what currently isn’t visible. For things like floors you can use a Planar Reflection actor to render correct reflections of things that aren’t visible.