Indoor Lighting

Design Lighting Distribution Sytem

March 01,2023

4.3 - Indirect Lighting

This example shows how Indirect Lighting can affect objects in the scene. Here we have a red light enclosed in a small space, with bounced light from the wall striking a static object and a dynamic one. Because indirect lighting is pre-calculated and baked into the static Lightmap, the static object's lighting and shadowing will be more accurate. For the dynamic object, however, lighting is dependent on the indirect lighting cache.

Static lights can also affect dynamic objects due to the Indirect Lighting Cache Sample Grid. This is a 3D grid of lighting samples that get baked into the scene and are used by the rendering engine to determine what effects static lighting will have on dynamic objects. The grid can be visualized in the viewport by typing the following command into the Console Bar in the upper-right corner of the editor:

r.Cache.DrawLightingSamples 1

You will see the samples scattered throughout the scene like so:

In order for the Indirect Lighting Cache samples to exist, your scene must have a Lightmass Importance Volume around it, and lighting must have been built by Lightmass.

Because dynamic objects are making use of this Indirect Lighting Cache, they have no way of knowing the actual position of the light, hence the lack of shadows seen in this example on the dynamic object.

Direktes und indirektes Licht

When do we use direct light?

As the name suggests, direct lighting is about a direct incidence of light. The light is bundled, usually from the ceiling, in a small beam angle of 10 ° to 60 ° and directly guided into the room. Direct light is always used when details need to be brought into focus: it has a narrow beam angle, creates an exciting contrast of light and shadow and is therefore mostly used for accent lighting. A desk lamp, for example, is used to provide the work surface with sufficient light. Good illumination of the kitchen workplace is achieved by directional spotlights or under-floor lights (link to AREA). Also at trade fairs, in museums, art galleries and in retail stores, light planners often rely on directional light in the form of LED spotlights or LED downlights that put individual objects in the foreground. For optimal working conditions in offices, the lighting must be adapted to the circumstances of the environment. Annoying shadows over the work surfaces should be avoided; Glare control is also important for flat angles. Since the ceiling usually appears dark, a so-called cave effect is created in the room. This creates high energy efficiency for the working level.