Generating lighting data

In Unity, precomputed lighting is generated in the background either as an automatic process or when manually initiated. It is possible to continue working in the editor while these processes run.

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 IlluminationA group of techniques that model both direct and indirect lighting to provide realistic lighting results.
See in Glossary and Baked Global Illumination. The progress bar displays information about the current process.

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 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 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 manually 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, disable the Auto Generate option in the Lighting Window and generate the lighting data manually for all your Scenes, to ensure that you do not lose any lighting data.

When you deactivate Auto Generate and manually 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.

Auto-Generate is not recommended for multi-scene workflows.