Lighting Window

The Lighting Window (menu: Window > Lighting) is the main control point for Unity’s Global Illumination (GI) features. Although GI in Unity gives good results with default settings, the window’s properties allow you to adjust many aspects of the GI process to customise your scene or optimise for quality, speed and storage space as you need. This window also contains lighting-related settings that were available under the Render Settings in Unity versions prior to 5.0. These include ambient light, halos, cookies and fog.

Overview

The controls of the Lighting window are divided among three tabs:

• The Object tab lets you choose subsets of the objects in your scene and change settings for them. This is very useful for selecting which objects should participate in the GI computations and also for applying settings consistently to groups of objects.

• The Scene tab has settings that apply to the scene overall rather than individual objects. These settings control lighting effects and also optimisation options.

• The Lightmaps tab shows the lightmap asset files generated by the GI process.

The tabs are described in full detail below.

Regardless of which tab is selected, the window also has an Auto checkbox near the bottom. If enabled, this allows the lightmap data to be updated while you edit the scene (although you should note that the update usually take a few seconds rather than happening instantaneously). If Auto is disabled then the Build button to the right of the checkbox becomes active; use the button to trigger lightmap updates as you need them. The Build button also has a dropdown menu with an option to clear the baked data from the scene (without clearing the GI Cache).

Below the Auto checkbox is a small panel showing lightmap statistics.

Object Tab

The Object tab lets you select groups of objects and apply settings to them.

At the top of the tab is a set of Scene Filter buttons that let you limit the hierarchy view to specific types of objects: Lights, Renderers, Terrains. Selecting All will show the hierarchy view as normal.

If you select any of the other buttons then the hierarchy view will be limited to showing just those object types. This is essentially just a quick way to access the standard hierarchy view filter for the most common cases.

Note that the filter does not affect which object is currently selected, so it is possible to have, say, a terrain object selected even when the hierarchy is filtered to show only lights.

The relevance of the filter buttons is that each of the three object types has its own set of properties, each described in detail below.

Lights

For a light object, the Object tab essentially shows the same information as the light component’s standard inspector panel. The properties that specifically affect GI are Baking and Bounce Intensity.

Baking allows you to choose if the light should be baked if Baked GI is selected. Mixed will also bake it, but it will still be present at runtime to give direct lighting to non-static objects. Realtime works both for Precomputed Realtime GI and when not using global illumination.

Bounce Intensity allows you to vary the intensity of indirect light (ie, light that is bounced from one object to another. The value is a multiple of the default brightness calculated by the GI system; if you set Bounce Intensity to a value greater than one then bounced light will be made brighter, while a value less than one will make it dimmer. This is useful, for example, when a dark surface in shadow (such as the interior of a cave) needs to be rendered brighter in order to make detail visible. Or alternatively, if you want to use Precomputed Realtime GI in general, but want to limit a single light to give direct light only, you can set its Bounce Intensity to 0.

Renderers

For Renderers, the following properties are available:

Terrains

For Terrains, the properties are a subset of those available for renderers.

Scene Tab

The Scene tab contains settings that apply to the scene overall as opposed to individual objects. Note that Precomputed Realtime GI and Baked GI features can be enabled or disabled by clicking the checkboxes next to their names in the Scene tab.

The Build button will start the lighting build process. The button can expand into a dropdown where you can clear the baked data. This isn’t the same as clearing the GICache.

Lightmaps Tab

The final tab provides an easy way to set and locate the lightmap asset file used for the scene.

If you click the filename in the Lightmap Snapshot box, the Project view will show you the asset file. If you click the small pip next to the box, an object selection window will appear to let you select a different lightmap. If you rename the folder where the current lightmap asset is located and then set the Lightmap Snapshot property to None, a new file will be created the next time you build the lightmap. Using multiple files like this is a good way to test out GI settings and compare different sets of parameters.

The image below the Lightmap Snapshot box shows a preview of the lightmap. This is only available when Baked lights are used; the preview will be blank for Realtime lights.