Table of Contents
What Aliasing Is
Due to the fact that the world is sampled and then rendered, possibilities for
errors exist. Depending on how the samples are taken, multiple worlds can
actually serve as aliases for one another and produce exactly the same sample
set. This incorrect rendering of a scene because a model is masquerading as one
of many other models who sample identically is called aliasing.
A very common type of aliasing is what is known as Temporal Aliasing. In
fact, almost everyone has experienced it when you watch a carŐs wheels
accelerate, or the blades of a helicopter accelerate. Because the eye can only
sample the world at a certain number of frames per second, objects appear to
behave peculiarly. It is for this reason that helicopter blades appear to
speed up, slow down, and then actually travel in reverse as the helicopter
powers up. The following movie illustrates an already flying helicopter. Note
that the blades appear to be moving forward quite slowly, when in reality they
are spinning at thousands of revolutions per minute.