Contours
Outer and Inner
In the context of the Overlay Graph, contours are used to represent the boundaries of geometric objects. These contours are classified into two types: outer contours and inner contours.
Outer Contour:
- An outer contour is a sequence of points ordered in a clockwise direction.
- The outer contour defines the external boundary of a shape, enclosing the exterior space.
Inner Contour (Hole or Cave):
- An inner contour is a sequence of points ordered in a counterclockwise direction.
- Inner contours represent enclosed areas within an outer contour, often referred to as "holes" or "caves."
Both outer and inner contours must be simple, meaning they must not self-intersect and must not share edges with other contours.