Atmospheric scattering of light is important in outdoor scenes. It changes sunlight from the
Interaction of Light with Particles
The interaction of light with particles is one of the most fundamental phenomena in graphics
(surface reflectance is derived from it as a special case). Light, as an electromagnetic wave, is
affected by the electromagnetic fields of particles of various kinds. When light interacts with a
particle, the particle may absorb the light (becoming more energetic as a result) or scatter it in
a new direction. Particles may also emit light on their own
paper. We assume a basic understanding of the physical nature of light and quantities such as
radiance and irradiance. If you wish to learn more about such topics there are introductions in
[Hoffman2001] and [Yee2002].
– we will ignore this possibility in this
pale red of dawn to the bright yellow of midday and back again. It determines the color and
brightness of the sky throughout the day, and it cues us to the distance of objects by shifting
their colors. All these effects vary not only based on time of day, but also depending on
weather, pollution and other factors. On planets with different atmospheric compositions, these
effects would differ significantly from those seen on Earth.
In this paper, we will explain the ways in which atmosphere affects light, including the
underlying theory. We will show the deficiencies of the commonly-used fog model, and
describe models which are more physically accurate.
