Introduction to lighting data

Precomputed lighting data and baked lighting are not the same.

Baked lighting data is static. For example, the appearance of a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary can change as it moves around a Light ProbeLight probes store information about how light passes through space in your scene. A collection of light probes arranged within a given space can improve lighting on moving objects and static LOD scenery within that space. More info
See in Glossary (if that GameObject has Contribute Global Illumination enabled). However, the data in the Light Probe itself does not change. Unity can store baked lighting data in lightmapsA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
See in Glossary, Light Probes, and Reflection Probes.

Enlighten Realtime Global IlluminationA group of techniques that model both direct and indirect lighting to provide realistic lighting results.
See in Glossary does not rely on baked lighting. Instead, it uses precomputed visibility data to speed up the process of determining how a light moving in real-time affects the surfaces that its rays can reach.

Generating lighting data

The Editor follows different steps to calculate EnlightenA lighting system by Geomerics used in Unity for Enlighten Realtime Global Illumination. More info
See in Glossary Realtime Global Illumination and Baked Global Illumination. The progress bar displays information about the current process. You can continue working in the Editor while the processes run.

The stages of lighting precomputation are listed below:

Enlighten Realtime Global Illumination

1. Create Geometry
2. Layout Systems
3. Create Systems
4. Create Atlas
5. Clustering
6. Visibility
7. Light Transport
8. Tetrahedralize Probes
9. Create ProbeSet

Probes

1. Ambient Probes
2. Baked/Realtime Ref. Probes

Generating data

Unity’s precomputed lighting solutions only consider static geometry. To begin the lighting precompute process, you need at least one Static GameObject in your SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary.

When you initiate a precompute, the Unity Editor evaluates and computes all aspects of your Scene lighting. To recalculate and bake only Reflection ProbesA rendering component that captures a spherical view of its surroundings in all directions, rather like a camera. The captured image is then stored as a Cubemap that can be used by objects with reflective materials. More info
See in Glossary, select the Generate Lighting option Reflection Probes Lighting Window.

Before you build

Before building your game, generate the lighting data for all your Scenes, to ensure that you do not lose any lighting data.

When you generate lighting for your Scene, Unity saves your lighting data as Asset files in your project directory. This ensures that the data you need is part of your build.