Version: 2021.3
Lighting
Light sources

Introduction to lighting

This page introduces you to how lighting works in Unity.

Lighting in Unity works by approximating how light behaves in the real world. Unity uses detailed models of how light works for a more realistic result, or simplified models for a more stylized result.

Direct and indirect lighting

Direct light is light that is emitted, hits a surface once, and is then reflected directly into a sensor (for example, the eye’s retina or a camera). Indirect light is all other light that is ultimately reflected into a sensor, including light that hits surfaces several times, and sky light. To achieve realistic lighting results, you need to simulate both direct and indirect light.

Unity can calculate direct lighting, indirect lighting, or both direct and indirect lighting. The lighting techniques that Unity uses depends on how you configure your Project.

Real-time and baked lighting

Real-time lighting is when Unity calculates lighting at runtime. Baked lighting is when Unity performs lighting calculations in advance and saves the results as lighting data, which is then applied at runtime. In Unity, your Project can use real-time lighting, baked lighting, or a mix of the two (called mixed lighting).

For information on configuring Light components to contribute real-time, baked, or mixed lighting, see Light ModesA Light property that defines the use of the Light. Can be set to Realtime, Baked and Mixed. More info
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Global illumination

Global illumination is a group of techniques that model both direct and indirect lighting to provide realistic lighting results. Unity has two global illuminationA group of techniques that model both direct and indirect lighting to provide realistic lighting results.
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systems, which combine direct and indirect lighting.

The Baked Global Illumination system consists of lightmappersA tool in Unity that bakes lightmaps according to the arrangement of lights and geometry in your scene. More info
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, Light ProbesLight 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
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, and 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
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. There are three options for baking: the Progressive Lightmapper (CPU or GPU), and Enlighten Baked Global Illumination.

The real-time Global Illumination system is Enlighten Realtime Global IlluminationA lighting system by Geomerics used in Unity for lightmapping and for Enlighten Realtime Global Illumination. More info
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See render pipeline feature comparison for more information about support for Lighting features across render pipelinesA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
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Lighting
Light sources