List of Figures

• Splitting an Edge into Half-Edges
• Idea Behind the Local Topological Formulæ
• The 8 Half-Edges Derived from One Intersection
• Expandable Array for Storing Edges in Cells
• Intersection Time vs Grid Size
• Topological Error Caused by Numerical Inaccuracy
• US Counties Versus Hydrography Polygons
• Distribution of Edges per Cell