How to Build Lighting Faster in Unreal Engine 5, Using GPU Lightmass

---

Introduction

In the realm of game development, efficient and realistic lighting plays a pivotal role in creating immersive environments. Unreal Engine 5 introduces the GPU Lightmass plugin, revolutionizing the process of light baking by harnessing the power of hardware-accelerated ray tracing. This guide, designed by Lost Crow Dev, walks you through optimizing your lighting build process in Unreal Engine 5, utilizing the GPU Lightmass plugin. From setup to execution, this document will provide detailed instructions to ensure you leverage this technology effectively, catering to both aesthetic quality and time efficiency.

GPU Lightmass Plugin

The GPU Lightmass plugin in Unreal Engine 5 is a groundbreaking tool that significantly enhances the light baking process by utilizing the GPU’s capabilities. This plugin is designed to compute light interactions more efficiently than traditional CPU-based methods, resulting in quicker build times and higher-quality lighting effects.

Pros:

• Enhanced Speed: Leveraging GPU power for faster lightmap baking.
• Superior Quality: Achieves more realistic lighting and shadow details.

Cons:

• Hardware Requirements: Only compatible with GPUs supporting hardware-accelerated ray tracing:
• Nvidia: RTX 20 series or newer.
• AMD: RX 6000 series or newer.
• Intel: Intel Arc GPUs (no integrated GPUs).
• Apple Silicon: M3 Macs and above.
• High VRAM Necessity: More VRAM equates to faster processing speeds.
• Performance Variability: Efficiency varies based on the GPU model and specifications.

Follow along with this step-by-step guide to optimize your lighting build process in Unreal Engine 5 using the GPU Lightmass plugin.

Steps for Faster Building Lighting in Unreal Engine 5

1. Disable Lumen:
   • Navigate to Project Settings -> Search Lumen.
   • Under “Global Illumination, Dynamic Global Illumination Method,” select None.
   • Under “Reflection Method,” set it to Screenspace.
2. Enable GPU Lightmass Plugin:
   • Go to Edit -> Plugins.
   • Enable GPU Lightmass (beta).
   • Note: Don’t restart the editor yet.
3. Enable Hardware Ray Tracing:
   • Navigate to Edit -> Project Settings.
   • Search for Hardware Raytracing.
   • Enable Support Hardware Ray Tracing.
   • Restart the editor now.
4. Access GPU Lightmass:
   • Go to Build -> GPU Lightmass.
   • This opens a new tab “GPU Lightmass”.
5. Configure GPU Lightmass Settings:
   • Generally, default options suffice.
   • Key Settings to Consider:
     • Disable Viewport Realtime is ON for faster builds.
     • Choose Mode: Full bake for entire level or Bake what you see for viewport-specific baking.
     • Keep Compress Lightmass enabled for reduced size with minimal quality loss.
6. Prepare Lighting:
   • Lights must be set to Static or Stationary.
   • Only four overlapping Stationary lights are allowed.
   • Movable lights are not baked.
7. Building the Lighting:
   • Click Build Lighting.
   • Confirm mesh upgrade if prompted.
   • Wait for the building process to complete.
8. Check Lightmap Data:
   • Navigate to Lit -> Optimization View Modes -> Lightmap Density.
   • Color Coding: Green = Perfect, Blue = Good, Red = Bad.
   • Adjust lightmap resolution for red areas by doubling the value in the Override Light Map Res setting under lighting properties.

Conclusion

This comprehensive guide provides a clear path for utilizing the GPU Lightmass plugin in Unreal Engine 5 to build lighting faster. It’s crucial to consider the hardware requirements and settings adjustments to optimize the lighting building process for your specific project needs.