To understand the complexity of Opsim, one must look at the two primary ways light is modeled within these systems.
This is the workhorse of Opsim. In this method, light is treated as a stream of particles (photons) traveling in straight lines. Engineers trace thousands, or even millions, of rays through an optical system. Each ray reflects off mirrors, refracts through lenses, and is absorbed by surfaces based on geometrical laws. To understand the complexity of Opsim, one must
