In this lesson, you will learn how to properly configure your project settings to unlock the full potential of Lumen, Unreal Engine’s dynamic global illumination and reflections system.
Enabling the Lumen Pipeline
To begin utilizing Lumen, you must ensure your project is operating within the correct rendering framework. Lumen relies on the Deferred Rendering path, which you have previously explored when studying G-Buffer storage and lighting calculations.
Navigate to Edit > Project Settings and locate the Rendering category. Under the Global Illumination section, change the dropdown menu from "None" or "Screen Space" to Lumen. Similarly, ensure that Reflections is set to Lumen.
Hardware and Driver Requirements
Lumen is a sophisticated system that leverages hardware acceleration. For the best stability and visual accuracy, you must ensure your project is targeting modern hardware capabilities. Within the same Rendering settings:
- Dynamic Global Illumination Method: Set to
Lumen. - Reflection Method: Set to
Lumen. - Shadow Map Method: Switch this to Virtual Shadow Maps for high-fidelity, high-resolution shadows that complement Lumen’s indirect lighting.
Ensuring Software Compatibility
Beyond just the toggles, Lumen requires specific hardware support to function correctly. Ensure your project settings are configured to use SM6 (Shader Model 6) or higher. You can verify this by checking the Default RHI settings under Platforms > Windows. If set to "Default," ensure your development machine is running an API that supports ray tracing features, such as DirectX 12.
; Example configuration for DefaultEngine.ini
[/Script/Engine.RendererSettings]
r.DynamicGlobalIlluminationMethod=1
r.ReflectionMethod=1
r.Shadow.Virtual.Enable=1
If you find that Lumen is not rendering as expected in your viewport, check the Support Hardware Ray Tracing checkbox under the Ray Tracing section. While Lumen can fall back to software ray tracing (using signed distance fields), hardware acceleration provides significantly higher performance and accuracy for complex geometry, especially when your scene is heavily utilizing Nanite assets. By aligning these settings, you provide the engine the necessary infrastructure to calculate light bounces in real-time.
Key Takeaway: To activate Lumen, you must set your Global Illumination and Reflection methods to 'Lumen' within the Rendering project settings, while ensuring your project is configured for DirectX 12 and Virtual Shadow Maps to maintain full dynamic fidelity.