How to Enable Light Propagation Volume in Unreal Engine 2018

This guide walks you through enabling Light Propagation Volume (LPV) in Unreal Engine 2018 to achieve dynamic, realistic lighting. You’ll learn setup steps, optimization tips, and how to fix common issues.

Key Takeaways

Light Propagation Volume (LPV) enables dynamic global illumination for moving lights and objects in Unreal Engine 2018.
LPV works best in indoor or enclosed environments where light bounces are critical for realism.
You must enable LPV in both Project Settings and Post Process Volumes for it to function correctly.
Use Static or Stationary lights with proper lightmap resolutions to avoid artifacts.
Performance can be impacted; adjust LPV quality settings based on your hardware and scene complexity.
Common issues like light leaks or flickering can often be resolved by adjusting grid resolution or light source settings.
LPV is not supported in all rendering paths—ensure you’re using Deferred Shading for compatibility.

Introduction: What Is Light Propagation Volume and Why Use It?

If you’re working in Unreal Engine 2018 and want more realistic lighting—especially in scenes with dynamic objects or moving lights—you’ve probably heard of Light Propagation Volume (LPV). LPV is a real-time global illumination technique that simulates how light bounces off surfaces, creating soft, natural lighting effects without requiring precomputed lightmaps.

Unlike baked lighting, which is static and can’t react to moving objects, LPV allows light to dynamically interact with the environment. This makes it ideal for games or simulations where lighting needs to feel alive and responsive. Whether you’re designing a dimly lit corridor, a sunlit room with shifting shadows, or a scene with flickering torches, LPV can significantly enhance visual fidelity.

In this guide, you’ll learn exactly how to enable Light Propagation Volume in Unreal Engine 2018, step by step. We’ll cover the setup process, best practices for performance and quality, and how to troubleshoot common problems. By the end, you’ll have a working LPV system that brings your scenes to life with realistic light behavior.

Step 1: Verify Your Project Settings

Visual guide about How to Enable Light Propagation Volume in Unreal Engine 2018

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Before enabling LPV, you need to make sure your project is configured correctly. LPV only works with certain rendering settings, so double-check these first.

Ensure Deferred Shading Is Enabled

LPV requires Deferred Shading to function. Here’s how to confirm it’s active:

Go to Edit > Project Settings.
In the left panel, navigate to Engine > Rendering.
Under the Rendering Features section, make sure Use Deferred Shading is checked.

If this option is disabled, LPV won’t work—even if you enable it elsewhere. Most modern projects use deferred shading by default, but it’s always good to verify.

Set the Correct Lighting Method

Next, ensure your project is set to use dynamic lighting methods that support LPV:

In Project Settings > Engine > Rendering, scroll down to Lighting.
Under Global Illumination Method, select Light Propagation Volume from the dropdown menu.

This tells Unreal Engine to prioritize LPV for global illumination instead of other methods like SSAO or precomputed lighting.

Step 2: Configure Light Propagation Volume Settings

Now that your project is set up, it’s time to configure the LPV system itself.

Access LPV Settings in Project Settings

Still in Project Settings > Engine > Rendering, scroll down to the Light Propagation Volume section.
You’ll see several options: Enable LPV, LPV Grid Resolution, LPV Intensity, and more.
Check the box next to Enable Light Propagation Volume.

This is the main switch that turns on LPV for your entire project.

Adjust LPV Grid Resolution

The LPV Grid Resolution controls how detailed the light simulation is. Higher values mean more accurate light bounces but at a higher performance cost.

Low (32): Good for testing or low-end hardware.
Medium (64): Balanced quality and performance—ideal for most projects.
High (128): Best visual quality, but may cause frame rate drops on complex scenes.

Start with 64 and adjust based on your scene and hardware. You can change this value anytime and see the effect in real time.

Set LPV Intensity and Other Parameters

You can fine-tune how strong the indirect lighting appears:

LPV Intensity: Controls the brightness of bounced light. Default is 1.0. Increase for brighter indirect lighting.
LPV Emissive Injection Intensity: Affects how much light is emitted from glowing materials. Useful for neon signs or lava.
LPV Specular Occlusion: Adds subtle shadowing to specular highlights. Enable for more realism.

These settings are subtle but can make a big difference in the final look. Experiment in your scene to find the right balance.

Step 3: Set Up Lights and Materials for LPV

LPV doesn’t work in a vacuum—it needs the right lights and materials to function properly.

Use Compatible Light Types

Only certain light types work well with LPV:

Stationary Lights: These are ideal. They cast dynamic shadows and contribute to LPV.
Static Lights: These can contribute to LPV if they have emissive materials, but they don’t cast dynamic shadows.
Movable Lights: These do not support LPV. Avoid using them if you rely on global illumination.

For best results, use Stationary lights with proper lightmap resolutions (at least 64 or higher). Low lightmap resolutions can cause light bleeding or artifacts.

Enable Emissive Materials

Materials that emit light (like neon tubes or glowing crystals) can inject light into the LPV system.

Open your material in the Material Editor.
Set the Material Domain to Surface.
Enable Emissive Color and set a color and intensity.
Make sure Use Emissive for Dynamic Area Light is checked in the material settings.

This allows the material to act as a light source within the LPV simulation.

Step 4: Use Post Process Volumes to Control LPV

Even with LPV enabled globally, you may want to control where it’s active. This is where Post Process Volumes come in.

Create a Post Process Volume

In the Place Actors panel, search for Post Process Volume.
Drag it into your level.
Resize it to cover the area where you want LPV active (e.g., a room or corridor).
Check Unbound if you want it to affect the entire level, or leave it unchecked to limit its range.

Enable LPV in the Volume

Select the Post Process Volume.
In the Details panel, expand the Light Propagation Volume section.
Check Enable Light Propagation Volume.
Adjust settings like LPV Intensity and LPV Grid Resolution if you want different values in this area.

This gives you fine-grained control over LPV behavior in different parts of your level.

Step 5: Test and Optimize Your Scene

Once everything is set up, it’s time to test.

Preview in Real Time

Press Play or use Simulate to see LPV in action. Move around the scene and observe how light bounces off walls and floors. Look for:

Soft, natural shadows

Color bleeding (e.g., red light tinting a white wall)

Responsive lighting when objects move

If the lighting looks flat or unchanged, double-check that LPV is enabled in both Project Settings and your Post Process Volume.

Optimize for Performance

LPV can be demanding. If you notice frame rate drops:

Lower the LPV Grid Resolution to 32 or 64.

Reduce the number of Stationary lights.

Avoid overly complex geometry in enclosed spaces.

Use Lightmass Importance Volume to focus lighting calculations on key areas.

Remember: LPV is best used in targeted areas, not entire open worlds.

Troubleshooting Common LPV Issues

Even with correct setup, you might run into problems. Here’s how to fix the most common ones.

Light Leaks or Bleeding

If light appears where it shouldn’t (e.g., through walls), it’s likely due to low lightmap resolution or gaps in geometry.

Increase Lightmap Resolution on affected meshes (at least 64–128).

Ensure walls and floors are sealed—no tiny gaps.

Use Blocking Volumes to seal off areas if needed.

Flickering or Flickering Shadows

This often happens with moving objects or low grid resolution.

Increase LPV Grid Resolution to 128.

Avoid very small or thin objects that can cause sampling errors.

Ensure lights are not too close to geometry.

LPV Not Working at All

Double-check:

Is Deferred Shading enabled?

Is LPV enabled in Project Settings?

Are you using Stationary or Static lights?

Is the Post Process Volume covering your test area?

Also, make sure you’re not in a mobile or forward rendering mode—LPV only works in deferred.

Conclusion: Bring Your Scenes to Life with LPV

Enabling Light Propagation Volume in Unreal Engine 2018 might seem complex at first, but once you understand the key steps, it becomes a powerful tool for creating immersive, dynamic lighting. By following this guide, you’ve learned how to configure LPV in Project Settings, set up compatible lights and materials, use Post Process Volumes for control, and troubleshoot common issues.

Remember, LPV shines (pun intended) in enclosed, detailed environments where light interaction matters. Use it wisely, optimize for performance, and don’t be afraid to experiment with settings. With LPV, your scenes won’t just look better—they’ll feel more alive.

Whether you’re building a horror game, a sci-fi corridor, or a cozy indoor space, realistic lighting can make all the difference. Now that you know how to enable and fine-tune Light Propagation Volume, you’re ready to take your Unreal Engine projects to the next level.