ABSTRACT
In Chapter 7 we discussed many aspects of lighting and shading. However, only the effects of point and directional light sources were presented, thus limiting surfaces to receiving light from a handful of discrete directions. This description of lighting is incomplete-in reality, surfaces receive light from all incoming directions. Outdoors scenes are not just lit by the sun. If that were true, all surfaces in shadow or facing away from the sun would be black. The sky is an important source of light, caused by sunlight scattering from the atmosphere. The importance of sky light can be seen by looking at a picture of the moon, which lacks sky light because it has no atmosphere (see Figure 8.1).
