2009

Multiplier A scalar multiplier for the light output. Default=1.0.
Haze In mr Physical Sky, the Haze setting corresponds to the Haze setting
used by the Haze-Driven sky model on page 5179.
Horizon Height The vertical position of the horizon.
The default value, 0.0, places the horizon at a standard height. However,
because the horizon is infinitely far away, this can cause trouble joining up
with any finite geometry that is supposed to represent the ground. It can also
cause issues rendering locations that are supposed to be at a high altitude, like
mountain tops or the top of New York skyscrapers where the horizon really
is visibly below the viewer.
This parameter allows tuning the position of the horizon. Note that this
horizon doesnt actually exist at a specific height in 3D space; it is a shading
effect for rays that go below a certain angle. This parameter tweaks that angle.
The total range available range is somewhat extreme, reaching from -10.0 (the
horizon is straight down) to 10.0 (the horizon is at the zenith). In practice,
only much smaller values are actually useful. For example, to push the horizon
down just below the edge of a finite visible ground plane, use 0.2.
NOTE The Horizon height affects not only the visual representation of the horizon
in the mr Sky light, but also the color of the mr Sun itself. In other words, the
point where the sun sets will change for a Horizon height settings other than
0.0.
5172 | Chapter 18 Lights and Cameras