|Rendering without global illumination. Areas that lie outside of the
ceiling lamp's direct light lack definition. For example, the lamp's
housing appears completely uniform. Without the ambient light added
into the render, it would appear uniformly black.
||Rendering with global illumination. Light is reflected by surfaces, and
colored light transfers from one surface to another. Notice how color
from the red wall (left) and green wall (right) reflects onto other
surfaces in the scene. Also notable is the caustic projected onto the red wall from light passing through the glass sphere.