Supercharge Your Lighting with GPU Lightmass

Supercharge Your Lighting with GPU Lightmass

Table of Contents

1. Introduction
2. Setting Up GPU Lightmass
3. Enabling Ray Tracing and Virtual Texturing
4. Enabling the GPU Lightmass Plugin
5. Creating a New Scene and Adding a Process Volume
6. Setting Up the Directional Light
7. Understanding Lightmap UVs
8. Adjusting Lightmap Resolution
9. Optimizing Ambient Occlusion
10. Disabling Lightmap Compression
11. Adding an HDRI Skylight
12. Bonus Tip: Adjusting Material Brightness

Introduction

In this article, we will explore the topic of GPU Lightmass and lighting for interiors. GPU Lightmass is a powerful tool that allows for high-quality real-time lighting in Unreal Engine. We will cover the process of setting up GPU Lightmass, enabling ray tracing and virtual texturing, optimizing lightmap UVs, adjusting lightmap resolution, optimizing ambient occlusion, disabling lightmap compression, adding an HDRI skylight, and a bonus tip on adjusting material brightness.

Setting Up GPU Lightmass

Before we dive into the fun stuff, it's important to ensure that your project is set up correctly for GPU Lightmass. In Unreal Engine 4.26, you will need an RTX-capable graphics card, enable ray tracing in your project settings, and enable virtual texturing. For detailed instructions on how to enable these features, refer to the official Epic documentation.

Enabling Ray Tracing and Virtual Texturing

If You have a graphics card that supports ray tracing, you can enable ray tracing in the project settings under the Edit tab. Go to Project Settings, click on the Virtual section, and enable virtual textures. Make sure to enable virtual texture support and virtual texture light maps.

Enabling the GPU Lightmass Plugin

To enable the GPU Lightmass plugin, go to the Settings bar, click on Plugins, and search for "GPU Lightmass" in the search bar. Make sure the plugin is enabled. After restarting the engine, you will be ready to use GPU Lightmass.

Creating a New Scene and Adding a Process Volume

To start working with GPU Lightmass, Create a new blank scene. One of the first steps is to add a Process Volume, which controls various post-processing settings. Drag and drop a Process Volume into the scene and ensure that the "Infinite Extent Unbound" option is checked in the details panel. Next, disable auto exposure by setting the exposure settings min and max values to 1.

Setting Up the Directional Light

Place a directional light in the scene and adjust its position and rotation to achieve the desired lighting effect. The directional light should be set to "Stationary" to ensure it contributes to the baked lighting. Adjust the light's brightness to achieve the desired illumination in the scene.

Understanding Lightmap UVs

Lightmap UVs are crucial for accurate lighting in Unreal Engine. Each static mesh in your scene should have two UV channels: one for texturing (UV channel 0) and one for light baking (UV channel 1). Ensure that none of the UV shells overlap to avoid shadowing artifacts. Refer to the Unreal Engine documentation and tutorials for detailed instructions on setting up lightmap UVs.

Adjusting Lightmap Resolution

To achieve high-quality lighting, it's important to adjust the lightmap resolution for each mesh in your scene. Select the meshes that require adjustments and increase the "Overridden Lightmap Res" value in the details panel. Higher resolutions will result in better lighting quality but may increase baking time and memory usage.

Optimizing Ambient Occlusion

By default, ambient occlusion is enabled in Unreal Engine. However, it can sometimes create unwanted shadowing artifacts. To disable ambient occlusion, select the post-process volume and set the intensity to zero in the details panel. Experiment with different settings to achieve the desired look and feel of the scene.

Disabling Lightmap Compression

Lightmap compression is enabled by default in Unreal Engine and helps reduce memory usage. However, it can result in splotchy and pixelated lighting. To disable lightmap compression, go to the World Settings window, uncheck "Compress Lightmaps," and rebuild the lighting. Keep in mind that disabling compression will increase memory usage.

Adding an HDRI Skylight

To enhance the lighting in your scene, you can add an HDRI skylight. Drag and drop an HDRI Backdrop into your scene and adjust its position and rotation. Ensure that the skylight is set to "Static" and uses the same HDRI as the backdrop. This will provide realistic outdoor lighting that shines through windows and adds depth to the scene.

Bonus Tip: Adjusting Material Brightness

The brightness of materials can significantly affect the overall lighting in your scene. If your materials are too dark, the quality of the lighting may be negatively impacted. To address this, consider increasing the brightness of your materials and then bake the lighting. Afterward, you can revert the material colors back to their desired darkness while maintaining a high-quality bake.

By following these steps and optimizing your GPU Lightmass settings, you can achieve realistic and visually appealing lighting for your interior scenes in Unreal Engine. Experiment with different settings, test variations, and remember to save and iterate to achieve the desired results.