The OpenGIS Geometry Model
978
•
GeometryCollection
(instantiable)
•
MultiPoint
(instantiable)
•
MultiCurve
(noninstantiable)
•
MultiLineString
(instantiable)
•
MultiSurface
(noninstantiable)
•
MultiPolygon
(instantiable)
It is not possible to create objects in noninstantiable classes. It is possible to create objects in
instantiable classes. All classes have properties, and instantiable classes may also have assertions
(rules that define valid class instances).
Geometry
is the base class. It is an abstract class. The instantiable subclasses of
Geometry
are restricted to zero-, one-, and two-dimensional geometric objects that exist in two-dimensional
coordinate space. All instantiable geometry classes are defined so that valid instances of a geometry
class are topologically closed (that is, all defined geometries include their boundary).
The base
Geometry
class has subclasses for
Point
,
Curve
,
Surface
, and
GeometryCollection
:
•
Point
represents zero-dimensional objects.
•
Curve
represents one-dimensional objects, and has subclass
LineString
, with sub-subclasses
Line
and
LinearRing
.
•
Surface
is designed for two-dimensional objects and has subclass
Polygon
.
•
GeometryCollection
has specialized zero-, one-, and two-dimensional collection classes named
MultiPoint
,
MultiLineString
, and
MultiPolygon
for modeling geometries corresponding
to collections of
Points
,
LineStrings
, and
Polygons
, respectively.
MultiCurve
and
MultiSurface
are introduced as abstract superclasses that generalize the collection interfaces to
handle
Curves
and
Surfaces
.
Geometry
,
Curve
,
Surface
,
MultiCurve
, and
MultiSurface
are defined as noninstantiable
classes. They define a common set of methods for their subclasses and are included for extensibility.
Point
,
LineString
,
Polygon
,
GeometryCollection
,
MultiPoint
,
MultiLineString
, and
MultiPolygon
are instantiable classes.
12.16.2.2. Class
Geometry
Geometry
is the root class of the hierarchy. It is a noninstantiable class but has a number of properties
that are common to all geometry values created from any of the
Geometry
subclasses. These
properties are described in the following list. Particular subclasses have their own specific properties,
described later.
Geometry Properties
A geometry value has the following properties:
• Its type. Each geometry belongs to one of the instantiable classes in the hierarchy.
• Its SRID, or Spatial Reference Identifier. This value identifies the geometry's associated Spatial
Reference System that describes the coordinate space in which the geometry object is defined.
In MySQL, the SRID value is just an integer associated with the geometry value. All calculations are
done assuming Euclidean (planar) geometry.
Содержание 5.0
Страница 1: ...MySQL 5 0 Reference Manual ...
Страница 18: ...xviii ...
Страница 60: ...40 ...
Страница 396: ...376 ...
Страница 578: ...558 ...
Страница 636: ...616 ...
Страница 844: ...824 ...
Страница 1234: ...1214 ...
Страница 1426: ...MySQL Proxy Scripting 1406 The following diagram shows an overview of the classes exposed by MySQL Proxy ...
Страница 1427: ...MySQL Proxy Scripting 1407 ...
Страница 1734: ...1714 ...
Страница 1752: ...1732 ...
Страница 1783: ...Configuring Connector ODBC 1763 ...
Страница 1793: ...Connector ODBC Examples 1773 ...
Страница 1839: ...Connector Net Installation 1819 2 You must choose the type of installation to perform ...
Страница 1842: ...Connector Net Installation 1822 5 Once the installation has been completed click Finish to exit the installer ...
Страница 1864: ...Connector Net Visual Studio Integration 1844 Figure 20 24 Debug Stepping Figure 20 25 Function Stepping 1 of 2 ...
Страница 2850: ...2830 ...
Страница 2854: ...2834 ...
Страница 2928: ...2908 ...
Страница 3000: ...2980 ...
Страница 3122: ...3102 ...
Страница 3126: ...3106 ...
Страница 3174: ...3154 ...
Страница 3232: ...3212 ...