ABSTRACT
We begin with emission and absorption and imagine a spatially varying function Le(p, ~ω) that describes the emission at a point in space along a given direction. For simplicity, we ignore the directional variation of Le and assume the function only changes with the position p, so we have Le(p). For absorption, we will let σa be the absorption coefficient, and using Beer’s law from the previous chapter, we know that transmittance between two points can be computed as T = e−σadt.
