Circular strings   A circular string is a collection of at least three points that typically make a curved line, although the points can be collinear. For more information, see ST_CircularString type

Compound curves   A compound curve is a collection of one or more linestrings, circular strings, or compound curves. For more information, see ST_CompoundCurve type.

Curve polygons   A curve polygon is similar to a polygon in that it has an exterior bounding ring and zero or more interior rings. However, more spatial data types are supported for the interior rings than for polygons (any ST_Curve value, for example). For more information, see ST_CurvePolygon type.

Geometries   The term geometry means the overarching type for objects such as points, linestrings, and polygons. The geometry type is the supertype for all supported spatial data types. For more information, see ST_Geometry type.

Geometry collections   A geometry collection is a collection of one or more geometries (such as points, lines, polygons, and so on). For more information, see ST_GeomCollection type.

Linestrings   A linestring is a line that connects two or more points in space. A linestring is a one-dimensional geometry with a specified length, but without any area. Linestrings can be characterized by whether they are simple or not simple, closed or not closed, where:

• Simple means a linestring drawn between two points that does not cross itself.
• Closed means a linestring that starts and ends at the same point.

For example, a ring is an example of simple, closed linestring.

For more information, see ST_LineString type.

In GIS data, linestrings are typically used to represent rivers, roads, or delivery routes.

Multipoints   A multipoint is a collection of individual points. The boundary around these points is empty. For more information, see ST_MultiPoint type.

In GIS data, multipoints are typically used to represent a set of locations.

Multipolygons   A multipolygon is one or more polygons defined together as a set.

In SQL Anywhere, multipolygons are specified using the ST_MultiPolygon type. See ST_MultiPolygon type

In GIS data, multipolygons are often used to represent geographic features such as a system of lakes or forestry reserves within a specific region.

Multilinestrings   A multilinestring is a collection of linestrings that connect two or more points in space.

In GIS data, multilinestrings are often used to represent geographic features like rivers or a highway network.

In SQL Anywhere, multilinestrings are specified using the ST_MultilineString type. See ST_MultiLineString type.

Points   A point defines a single location in space. A point geometry does not have length or area. A point always has an X and Y coordinate.

In GIS data, points are typically used to represent locations such as addresses, or geographic features such as a mountain.

In SQL Anywhere, points are specified using the ST_Point type. See ST_Point type.

Polygons   A polygon is a collection of points that represent a two dimensional surface. A polygons is constructed of one or more rings (boundaries)—an exterior bounding ring, and zero or more interior rings—and has an associated length and area.

In GIS data, polygons are typically used to represent territories (counties, towns, states, and so on), lakes, and large geographic features such as parks.

In SQL Anywhere, polygons are specified using the ST_Polygon type. See ST_Polygon type.

See also: Polygon ring orientation

Multisurfaces   In SQL Anywhere, multisurfaces are specified using the ST_MultiSurface type. See ST_MultiSurface type.