# Emissive lighting with a hidden/invisible object

**URL:** <https://forums.unrealengine.com/t/emissive-lighting-with-a-hidden-invisible-object/852873>\
**Category:** Rendering\
**Tags:** unreal-engine\
**Created:** [April 5, 2023, 4:21pm UTC](https://forums.unrealengine.com/t/emissive-lighting-with-a-hidden-invisible-object/852873 "2023-04-05T16:21:46Z")\
**Posts on this page:** 1\
**Showing post:** 15

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**Author:** ![Arkiras](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/arkiras/32/1008648_2.png) [@Arkiras](https://forums.unrealengine.com/u/Arkiras)\
**Post date:** [April 20, 2023, 2:16pm UTC](https://forums.unrealengine.com/t/emissive-lighting-with-a-hidden-invisible-object/852873/15 "2023-04-20T14:16:25Z")

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@BenVlodgi posted this in another thread and thought it would be relevant here:

> [@Emissive material only visible to Lumen (invisible in game)](https://forums.unrealengine.com/t/emissive-material-only-visible-to-lumen-invisible-in-game/620888/2):
>
> 5.1 Added AffectIndirectLightingWhileHidden. [Release Notes](https://docs.unrealengine.com/5.1/en-US/unreal-engine-5.1-release-notes/). Added an AffectIndirectLightingWhileHidden property to the Primitive Component, which allows hidden primitives to be injected into Global Illumination (GI) and Reflections. This is useful as an extra art direction tool to create cheap invisible area lights through GI.

Didn’t notice this in the release notes. It still seems to require disabling screen traces to get decent results, but at least you don’t have to set up a material switch for the Lumen scene which makes it easier to work with since you can actually see what you’re doing.

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