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 counterclockwise 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 clockwise 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.