PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

Lines
Figure 2.1: Point feature [27].
Lines represent the shape of geographic objects that are too narrow to be depicted as areas (such
as street centerlines and streams). Lines are also used to represent features that have length but no
area such as contour lines and administrative boundaries.
Polygons
Figure 2.2: Line feature [27].
Polygons are enclosed areas that represent the shape of large objects such as states, counties,
parcels, soil types and landuse zones.
2.2.2 Attributes
Geographic data transmits descriptive information through symbols, colors, and labels. For example:
• Roads are displayed based on road class. For instance, line symbols represent divided highways,
main streets, residential streets, unpaved roads and trails.
• Blue is used to indicate water and streams.
• City streets are labeled with their name and often some address.
• Special point and line symbols denote specific features such as rail lines, airports, schools, hospitals
and special facilities.
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