Realtime Global Illumination appears available in URP/HDRP but does not work at runtime

Unity Engine
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1

Hello,

I’m currently working with Unity 2022 and experimenting with Realtime Global Illumination (Enlighten).

According to the documentation, Realtime GI is not supported in URP and HDRP.
However, in both pipelines:

  • The Realtime Global Illumination option is still accessible in the Lighting Settings
  • Realtime Lightmaps are generated and visible in the Realtime Lightmaps tab
  • The system appears to update correctly in the Editor when lights are modified

Despite this, at runtime:

  • Indirect lighting does not react to realtime lights
  • Enabling/disabling lights or changing intensity has no visible GI effect
  • The behavior is identical in both URP and HDRP

Interestingly, I had the impression that I briefly managed to get Realtime GI working in HDRP on a new, clean scene:

  • Realtime Lightmaps appeared to update correctly
  • Indirect lighting seemed to react to realtime light changes

However, after further changes, this behavior stopped working, and I’ve been unable to reproduce it reliably since then.

This raises a few questions:

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  1. Is this behavior expected (Editor-only visualization)?
  2. Why is Realtime GI still exposed in URP/HDRP if it is not functional at runtime?
  3. Are Realtime Lightmaps in these pipelines intended for editor/debug preview only?
  4. Could there be edge cases or partial support that explain this inconsistent behavior?

Additionally, regarding the current alternatives in HDRP:

While SSGI (Screen Space Global Illumination) is available, in practice it has several limitations:

  • Noticeable temporal instability when the camera moves
  • GI contribution seems to update only when approaching surfaces
  • Difficult to stabilize for slow-paced indoor environments
  1. Is there any official replacement planned for dynamic GI in HDRP, beyond SSGI and DXR-based RTGI?

I would appreciate an official clarification on the intended workflow and long-term direction for dynamic GI in Unity.

2

@Pema-Malling :slight_smile:

3

Hello. Realtime GI with Enlighten is supported in both URP and HDRP. Where did you read that it wasn’t?

To answer your questions:

  1. No.
  2. It is supported, looks like you are hitting a bug.
  3. No.
  4. Enlighten realtime GI should be fully supported.
  5. Sort of. We are working on a new realtime GI system for the Unity 6 cycle. You can see a sneak peek here https://youtu.be/K3-wPnhmDi4?si=iTZ9W3CGQJcZruG0&t=3224. Currently we are focusing on URP support - no public info about HDRP yet.

You are probably hitting some bug in the Enlighten integration. Either that or it is user error, kind of hard for me to tell without access to the project. I suggest filing a bug report either way. Enlighten RTGI should work.

Also check this thread Feedback Request: Changes to Unity's Dynamic GI Roadmap

4

Hello @Pema-Malling, Thanks for your clarifications. Actually, I tried to set up Real Time GI but I can’t see any difference. I asked first on the AI Agent in Unity 6.3 and ChatGPT if the Real Time GI is also compatible with URP and HDRP. The answers were not clear at all. That’s why I was asked this question here.

I finally understand how to add Realtime GI. I added a bigger value in the indirect multiplier field.

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However, I got this warning but I can see the lighting bouncing to the walls.

“Realtime Indirect Bounce is not supported for spot and point lights”

5

SSGI requires reflection probes. It’s basically useless without them.

6

Actually, I’m not using SSGI but Enlighten.

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