5 Unreal Engine 5 Lighting Secrets Every Game Developer Must Know

Lighting is often the unsung hero in game development, capable of turning a bland scene into a breathtaking visual experience—or tanking your frame rate if mishandled. Unreal Engine 5 introduces groundbreaking tools like Lumen, promising realistic, dynamic lighting with minimal fuss. Yet beneath the surface, there are surprising trade-offs and lesser-known strategies that can make or break your project’s performance and visual quality.

Lumen’s Power Comes with a Hidden Performance Cost

Lumen is Unreal Engine 5’s real-time global illumination system, designed to deliver dynamic lighting effects like light bounces and reflections without any pre-baking. While this sounds like a dream come true, Lumen’s demanding nature can severely impact performance, especially on mid-range GPUs.

Developers often expect to enable Lumen and instantly achieve stunning visuals, but the reality includes significant resource consumption and occasional visual artifacts such as ghosting—an unwanted trailing effect around moving lights or objects.

“Lumen’s magic is real—but it’s not free. Expect trade-offs between visual fidelity and frame rates.”

Understanding this balance is critical: while Lumen evolves with each Unreal Engine update, blindly trusting default settings can introduce unexpected issues that frustrate both artists and players.

“Baked Lighting” Is Like Digitally Painting Light onto Your Scene

Contrary to dynamic lighting, baked lighting involves precalculating how light interacts within a static scene and embedding that information directly into textures. Think of it as digitally painting shadows and illumination onto surfaces, eliminating runtime calculations.

This approach dramatically improves performance since the engine simply displays the pre-rendered lighting instead of recalculating it every frame. In practice, this means static objects remain beautifully lit even if their light sources are removed during gameplay.

For projects prioritizing frame rate or targeting less powerful hardware, mastering baked lighting techniques remains invaluable.

“Baked lighting offers a near-zero runtime cost by turning complex light calculations into static art.”

Point Lights Are Performance Pitfalls—Use Them Sparingly

When working with traditional dynamic lighting, it’s tempting to add numerous Point Lights (which emit light in all directions) to create rich, immersive environments. However, this is a costly choice. Each Point Light requires the engine to render six shadow maps—one per face of a cube—to simulate 360° shadows.

This means a single Point Light can be six times more expensive than other dynamic lights like spotlights or directional lights, quickly draining performance if overused.

Developers must consider alternative lighting strategies or optimize Point Light usage to prevent unexpected frame rate drops.

“A single Point Light is like running six cameras simultaneously—tread carefully.”

Emissive Materials Don’t Always Illuminate—Know When They Do

Emissive materials—those that glow or appear self-illuminated—can be confusing for newcomers. While a neon sign’s material might look brilliantly lit, it won’t necessarily cast light onto nearby objects unless the lighting system supports it.

In Lumen-enabled projects, emissive materials naturally contribute to global illumination, dynamically lighting their surroundings in real time. Conversely, in baked lighting workflows, emissive effects are purely visual unless specifically baked into the scene’s lightmaps.

This distinction is crucial for artists and developers aiming for realistic lighting effects without unexpected dark spots or mismatched glow.

• Lumen: Emissives act as real light sources.

• Baked Lighting: Emissives require manual baking to affect environment lighting.

Megalightes: Unlocking Massive Dynamic Light Counts with Ray Tracing Hardware

Unreal Engine’s new Megalightes system offers a game-changing solution for scenes that demand thousands of dynamic lights without crippling performance. By leveraging hardware-accelerated ray tracing on compatible GPUs (like NVIDIA RTX cards), Megalightes dramatically boosts frame rates while maintaining lighting complexity.

For example, a test scene with 648 dynamic lights ran at 75 FPS normally, but soared to 130 FPS using Megalightes on an RTX 3070. Importantly, this technology isn’t exclusive to Lumen—it can optimize traditional lighting setups as well.

This opens exciting possibilities for developers who want to combine vast light counts with efficient rendering, provided they have the right hardware and enable “Hardware Raytracing” in project settings.

“Megalightes shatter previous limits, enabling thousands of dynamic lights with minimal performance cost—if your hardware can handle it.”

Mastering lighting in Unreal Engine 5 demands more than flipping switches; it requires a nuanced understanding of each system’s strengths, costs, and quirks. Whether balancing the dynamic realism of Lumen, the efficiency of baked lighting, or harnessing cutting-edge tools like Megalightes, your choices shape both the beauty and performance of your projects. With these secrets in hand, how will you illuminate your next virtual world?