Circle event happens when a parabolic arc shrinks to a point and disappears
from the parabolic front (Figure 5). Let be the disappearing arc and
and
are two neighboring arcs before
disappears. These arcs are then
defined by three different points pi , pj
and pk . At the moment when
disappears, all three arcs pass through a
common point q (Figure 5). The distance between q and the scanning
line is the same as the distance from q to all three points
pi , pj and pk . These
three points define a circle, with its center at point q which represents
the Voronoi point. The lowest point of this circle touches the scanning line and
represents the circle event.
It is possible that the circle event is tried to be destroyed by some other event ("false event" or "false alarm"). Such events must be destroyed and removed from the data structure. As will be explained later, the detection of the false alarms is trivial.
Roman Cuk - roman.cuk@uni-mb.si