Baked lighting

Baked Lights are Light components which have their Mode property set to Baked.

Use Baked mode for Lights used for local ambience, rather than fully featured Lights. Unity pre-calculates the illumination from these Lights before run time, and does not include them in any run-time lighting calculations. This means that there is no run-time overhead for baked Lights.

Unity bakes direct and indirect lighting from baked Lights into light maps (to illuminate static GameObjects) and 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
See in Glossary (to illuminate dynamic Light GameObjects). Baked Lights cannot emit specular lighting, even on dynamic GameObjectsThe 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 (see Wikipedia: Specular highlight for more information). Baked Lights do not change in response to actions taken by the player, or events which take place in the 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. They are mainly useful for increasing brightness in dark areas without needing to adjust all of the lighting within a Scene.

Baked Lights are also the only Light type for which dynamic GameObjects cannot cast shadows on other dynamic GameObjects.

Advantages of baked lighting

• High-quality shadows from statics GameObjects on statics GameObjects in the light map at no additional cost.

• Offers indirect lighting.

• All lighting for static GameObjects can be just one Texture fetched from the light map in the ShaderA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
  See in Glossary.

Disadvantages of baked lighting

• No real-time direct lighting (that is, no specular lighting effects).

• No shadows from dynamic GameObjects on static GameObjects.

• You only get low-resolution shadows from static GameObjects on dynamic GameObjects using Light Probes.

• Increased memory requirements compared to real-time lighting for the light map texture set, because light maps need to be more detailed to contain direct lighting information.

Technical details

For baked Lights, Unity precomputes the entire light path, except for the path segment from the CameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary to the Surface. See documentation on Light ModesA Light property that defines the use of the Light. Can be set to Realtime, Baked and Mixed. More info
See in Glossary for more information about light paths.

Unity also precomputes direct baked lighting, which means that light direction information is not available to Unity at run time. Instead, a small number of Texture operations handle all light calculations for baked Lights in the Scene area. Without this information, Unity cannot carry out calculations for specular and glossy reflections. If you need specular reflections, use 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 or use Mixed or Realtime lights. See documentation on directional light maps for more information.

Baked Lights never illuminate dynamic GameObjects at run time. The only way for dynamic GameObjects to receive light from baked Lights is via Light Probes. This is also the only difference between Baked Lights and any Subtractive mode Mixed Lights (except the main directional Light) which compute direct lighting on dynamic GameObjects at run time.

• 2017–06–08 Page published with limited editorial review

• Light Modes added in 5.6