The simplest application of daylight is exterior modeling. Many CAD systems have built-in renderers that will compute the solar position from time of day, year, and location, and generate accurate shadows. In addition to this functionality, we wanted Radiance to show the contributions of diffuse skylight and interreflection. A more difficult daylighting problem is atrium design. Designing an atrium requires thorough understanding of the daylight availability in a particular region to succeed.
Daylighted interiors pose one of the nastiest challenges in rendering.
Because sunlight is so intense, it is usually diffused or baffled by louvers or other redirecting systems. Some of these systems can be quite elaborate, emphasizing the need for simulation in their design. Figure 18 shows the interior of the pavillion from Figure 16 . Figure 19 shows a library room illuminated by a central skylight. Figure 20a shows a simulation of a daylighted museum interior.