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What you'll learn:

Configure project settings for Lumen and ray tracing

Create a blank environment to build lighting from scratch

Understand mesh and light mobility settings

Section 1: Project Settings (8 min)

Before creating any scenes, verify your project's rendering settings are configured correctly.

Edit → Project Settings → Engine → Rendering

Edit menu - Project Settings

Project Settings navigation

Engine Rendering settings

Working Color Space

Setting	Value
Working Color Space	sRGB / Rec709

Global Illumination

Setting	Value
Dynamic Global Illumination Method	None

Note: We'll cover this in depth in Part 5: Indirect Lighting.

Reflections

Setting	Value	Note
Reflection Method	None	We'll enable Lumen later when discussing reflections

Lumen

Setting	Value
Use Hardware Ray Tracing when available	✓ On
Ray Lighting Mode	Surface Cache

Info: Surface Cache is faster (caches lighting data on surfaces); Hit Lighting is more accurate but slower (evaluates lighting at each ray hit). Surface Cache is the recommended default for most workflows.

Note: We'll cover Ray Lighting Mode in Part 7: Reflections.

Direct Lighting

Setting	Value
Ray Traced Shadows	Off
Shadow Map Method	Virtual Shadow Maps

Hardware Ray Tracing

Setting	Value
Support Hardware Ray Tracing	✓ On

Hardware Ray Tracing Requirements:

NVIDIA: RTX 2000 series or newer
AMD: RX 6000 series or newer
Windows: Windows 10 Build 1809+ with DirectX 12
Linux: Supported via Vulkan (experimental) — requires Vulkan-capable GPU drivers
Consoles: PS5, Xbox Series S/X have native support

If your GPU doesn't support hardware ray tracing, Lumen falls back to software ray tracing (slower but still functional). Keep GPU drivers up to date for best performance.

Troubleshooting: Option Missing or Greyed Out?

If the Hardware Ray Tracing option is missing or greyed out, check:

Not running DirectX 12 — Ensure your project uses D3D12 as the RHI (see Platform Settings below)
GPU doesn't support DXR — Your graphics card may not support DirectX Raytracing
Outdated drivers — Update to the latest GPU drivers from NVIDIA/AMD
Windows version — Requires Windows 10 Build 1809+ with DirectX 12 support

Software Ray Tracing

Setting	Value
Generate Mesh Distance Fields	✓ On

Info: Distance Fields are used by Lumen's software ray tracing fallback and for Distance Field Ambient Occlusion. Enable this even if you have RT hardware — it provides fallback support and some additional features.

Default Settings

Setting	Value
Light Units	Lumens
Bloom	Off
Ambient Occlusion	Off
Ambient Occlusion Static Fraction	Off
Auto Exposure	Off
Motion Blur	Off
Lens Flare	Off

Why disable these? We disable these post-processing effects initially so we can see the pure lighting contribution without any enhancements. This helps you understand what each lighting element does on its own. You can re-enable them later once you understand your lighting setup.

Forward Renderer

Setting	Value
Forward Shading	Off

Why Off? Unreal uses Deferred Rendering by default, which is required for Lumen GI and most modern lighting features. Forward Shading is an alternative rendering path used for specific cases like MSAA anti-aliasing, VR optimization, or certain transparency/hair rendering techniques. For this course, keep it Off to use the standard deferred pipeline with Lumen.

Hardware Ray Tracing and many Lumen features require DirectX 12 and Shader Model 6. Configure these in Platform Settings:

Edit → Project Settings → Platforms → Windows

Platforms navigation

Windows Platform Settings

D3D12 Targeted Shader Formats

Setting	Value	Why
SM6	✓ On	Required for hardware ray tracing and modern Lumen features
SM5	Off	Legacy shader model — lacks ray tracing intrinsics and wave operations

SM5 vs SM6: Shader Model 5 (SM5) was designed for DirectX 11 and doesn't support hardware ray tracing. Shader Model 6 (SM6) adds DXR ray tracing intrinsics, wave operations for better GPU parallelism, and other features Lumen relies on. If you're using Lumen with hardware ray tracing, SM6 is required.

Targeted RHIs

Setting	Value	Why
Default RHI	DirectX 12	RHI (Render Hardware Interface) is Unreal's abstraction layer. DirectX 12 provides the low-level GPU access needed for hardware ray tracing and optimal Lumen performance

Note: After changing RHI settings, restart the editor for changes to take effect.

Section 2: Blank Environment (7 min)

A blank level removes all assumptions. No default lighting, no sky, no post-processing. This lets us:

See exactly what each component contributes
Understand why things look "wrong" when elements are missing
Build up lighting systematically

File → New Level → Empty Level

File menu - New Level

New Level dialog - Empty Level selected

Result: Complete darkness (no lights exist)

Empty Level - Complete Darkness

To add anything to your scene:

Window → Place Actors (or press Shift+1)

Window menu - Place Actors

Place Actors panel - Shapes

This opens the Place Actors panel where you can find:

Basic shapes (cube, sphere, cylinder, etc.)
Lights (point, spot, rect, directional)
Volumes (post process, etc.)
And more

Create a floor:

Place Actors → Shapes → Cube
Scale it: X = 10, Y = 10, Z = 0.1 (flat platform)
Position at Z = 0

Add test objects:

Place Actors → Shapes → Cube
Position it on the floor
Place Actors → Shapes → Cylinder
Position next to the cube

Now you have a simple scene to light.

Test Geometry Setup - Cube and Cylinder on floor

Tip: If you need to see your scene, switch the viewport from Lit to Unlit (Viewport > View Mode > Unlit, or press Alt+3). This shows objects without lighting so you can position them. Switch back to Lit mode (Alt+4) once you add lights.

Every mesh in Unreal has a Mobility setting that controls whether it can move and how the engine optimizes it:

Details panel showing Mobility setting

Mobility options - Static, Stationary, Movable

Mobility	Can Move?	Performance Benefit
Static	No	Lowest transform overhead, shadow depth caching
Stationary	No	Shadow map caching for better dynamic shadow performance
Moveable	Yes	Required for anything that moves at runtime

For this course, we're using fully dynamic lighting (Lumen), not baked lightmaps.

Window → World Settings (or click the Settings dropdown in the toolbar)

Setting	Value	Why
Force No Precomputed Lighting	✓ On	Disables lightmap baking — all lighting is real-time

Window menu - World Settings

In the World Settings panel, find the Lightmass section → Lightmass Settings → Advanced:

World Settings panel

The setting is located in Advanced Lightmass:

Force No Precomputed Lighting setting

When you enable this setting, you'll see a confirmation dialog asking you to rebuild lighting:

Force No Precomputed Lighting warning

Click OK. The setting is now enabled:

Setting enabled

Note: Baked lighting (lightmaps) is a separate workflow optimized for static scenes. This course focuses on fully dynamic lighting with Lumen, which is more flexible for real-time changes.

Warning: What you're trading away: Baked lightmaps offer better performance on lower-end hardware and consistent results without temporal noise. By forcing dynamic lighting, you gain flexibility but require more GPU power and accept potential frame-to-frame variation.

With Force No Precomputed Lighting enabled, all meshes receive fully dynamic lighting. However, the Mobility setting still matters for performance:

Mobility	Use Case	Performance Benefit
Static	Floors, walls, props that don't move	Lowest transform overhead, shadow depth caching
Stationary	Lights/objects that won't move but need dynamic shadows	Shadow map caching, cheaper than Moveable
Moveable	Objects that move during gameplay	Required for runtime transforms

Tip: Lights also have Mobility settings — see Part 2: Direct Lighting.

Without any lights, your scene is completely black. This is intentional — Unreal doesn't fake ambient lighting. If there's no light source, there's no light. This physically correct behavior helps you understand exactly what each light contributes.

After enabling Force No Precomputed Lighting, build the level to apply the change:

Why rebuild and save? Building and saving ensures any existing baked lighting data is cleared from the level. Without this step, old lightmaps could remain associated with the level and cause unexpected lighting behavior.

Build → Build All Levels

Build menu