Geographic Data (Cont.) Vector data are constructed from basic geometric objects:points, line segments,triangles,and other polygons in two dimensions,and cylinders,speheres,cuboids,and other polyhedrons in three dimensions. Vector format often used to represent map data. Roads can be considered as two-dimensional and represented by lines and curves. Some features,such as rivers,may be represented either as complex curves or as complex polygons,depending on whether their width is relevant. Features such as regions and lakes can be depicted as polygons. 15 Database System Concepts,5th Ed. 24.15 @Silberschatz,Korth and SudarshanDatabase System Concepts, 5 24.15 ©Silberschatz, Korth and Sudarshan th Ed. 15 Geographic Data (Cont.) Vector data are constructed from basic geometric objects: points, line segments, triangles, and other polygons in two dimensions, and cylinders, speheres, cuboids, and other polyhedrons in three dimensions. Vector format often used to represent map data. Roads can be considered as two-dimensional and represented by lines and curves. Some features, such as rivers, may be represented either as complex curves or as complex polygons, depending on whether their width is relevant. Features such as regions and lakes can be depicted as polygons