The driver uses displays and indicators to obtain information, which could be standard dashboard instrumentation information or more complex information from a navigation system, a menu-driven display, or a multimedia device. For display and indicator lighting, the key metrics are color, luminance, and luminance uniformity.
Interior Illumination systems provide light to enable the driver or passengers to see something else. These systems include dome lights, mirror lights to illuminate a face, map and reading lamps, storage lights, and so on. For Illumination systems, the key metrics are the geometry of the illuminated area, illuminance levels, and uniformity. Color can also a factor, both for visibility issues and for custom "mood" lighting.
The primary purposes of accent lighting is to provide styling cues, create a desired ambience and to locate various controls, such as power window controls and radio knobs, and other features, such as cup holders and charging ports, in a darkened cabin. Accent lighting generally has a much lower intensity than interior illumination fixtures since the goal is not to illuminate other objects in the cabin, but just to be visible itself. The main design concerns with this type of lighting are color, visual uniformity, and appropriate light levels.