Lighting
Light types, Lumen global illumination, Sky Atmosphere, and lightmap baking in UE5.
Light Types
| Light | Shape | Use Case |
|---|---|---|
| Directional Light | Infinite parallel rays | Sun, moon — one per scene. |
| Point Light | Omnidirectional sphere | Bulbs, campfires, lanterns. |
| Spot Light | Cone | Flashlights, stage spots, car headlights. |
| Rect Light | Rectangle | Windows, studio panels, TV screens. |
| Sky Light | Captures scene horizon | Ambient fill from the sky and distant environment. |
Lumen Global Illumination
Lumen is UE5's fully dynamic GI and reflection system. It computes indirect bounce light in real time — no lightmap baking required. Interior spaces darken correctly, emissive surfaces cast colored light, and reflections update as the scene changes.
Lumen uses Software Ray Tracing (mesh distance fields) on all DX11+ hardware, and optionally Hardware Ray Tracing (RTX/RDNA2+) for higher-quality reflections and higher-accuracy GI.
In Project Settings → Rendering, enable Dynamic Global Illumination: Lumen and Reflections: Lumen. Requires SM5 or higher.
Sky & Atmosphere
The Sky Atmosphere component simulates physically-based atmospheric scattering — Rayleigh and Mie — for realistic time-of-day skies. Pair it with a Volumetric Cloud component and an Exponential Height Fog for complete outdoor environments.
Light Mobility
| Mobility | GI | Shadows | Cost |
|---|---|---|---|
| Static | Baked lightmaps | Baked | Zero runtime cost |
| Stationary | Baked indirect + dynamic direct | Distance Field shadows | Low |
| Movable | Lumen (fully dynamic) | Ray-traced / VSM | Highest |
Shadow Techniques
- Virtual Shadow Maps (VSM) — UE5's default. High-quality shadows at any scale. Works with Nanite geometry.
- Ray-Traced Shadows — Hardware RT shadows. Most accurate, highest cost.
- Distance Field Shadows — Fast soft shadows from mesh SDF. Good for Stationary lights.
- Cascaded Shadow Maps (CSM) — Traditional technique for Directional lights in legacy projects.