Lighting Data Asset

Lightmap Snapshot was renamed to Lighting Data Asset in Unity 5.3.

You generate the Lighting Data Asset by pressing the Build button in the Lighting window. Your lighting will be loaded from that asset when you reload 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.

The Lighting Data Asset contains the GI data and all the supporting files needed when creating the lighting for a scene. The asset references the renderers, the realtime 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, the baked lightmaps, 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, 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 and some additional data that describes how they fit together. This also includes all the EnlightenThe lighting system by Geomerics used in Unity for computing global illumination (GI). More info
See in Glossary data needed to update the realtime global illumination in the Player. The asset is an Editor only construct so far, so you can’t access it in the player. When you change the scene, for instance by breaking a prefabAn asset type that allows you to store a GameObject complete with components and properties. The prefab acts as a template from which you can create new object instances in the scene. More info
See in Glossary connection on a lightmap static object, the asset data will get out of date and has to be rebuilt.

Currently, this file is a bit bloated as it contains data for multiple platforms - we will fix this. Also we are considering adding some compressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
See in Glossary for this data.

The intermediate files that are generated during the lighting build process, but is not needed for generating a Player build is not part of the asset, they are stored in the GI CacheThe cached intermediate files used when Unity precomputes real-time GI, and when baking Static Lightmaps, Light Probes and Reflection Probes. Unity keeps this cache to speed up computation. More info
See in Glossary instead.

The build time for the Lighting Data Asset can vary. If your GI Cache is fully populated i.e. you have done a bake on the machine before (with the scene in its current state) it will be fast. If you are pulling the scene to a machine with a blank cache or the cache data needed has been removed due to the cache size limit, the cache will have to be populated with the intermediate files first which requires the precompute and bake processes to run. These steps can take some time.