Indicating the coordinate system in which it is embedded. If it has both Z and M the coordinate dimension is 4D. If a geometry has Z or M ordinates the coordinate dimension is 3D If Z or M values are present in a geometry value, they must be defined for each point in the geometry. ![]() The M ordinate contains a measure value, which may represent time or distance. The Z ordinate is often used to represent elevation. Shapes are constructed from points or line segments, with points specified by a single coordinate,Ĭoordinates may contain optional Z and M ordinate values. The size and location of shapes are specified by their coordinates.Įach coordinate has a X and Y ordinate value determining its location in the plane. The PolyhedralSurface, Triangle, and TIN types can also represent shapes in 3-dimensional space. Geometry models shapes in the 2-dimensional Cartesian plane. The Simple Features Access - Part 1: Common architecture v1.2.1 Which represent various kinds and dimensions of geometric shapes. Geometry values belong to one of its concrete subtypes PostGIS implements the OGC Geometry model as the PostgreSQL data types It defines the fundamental spatial type of Geometry,Īlong with operations which manipulate and transform geometry values ![]() Standard (SFA) to provide a model for geospatial data. ![]() The Open Geospatial Consortium (OGC) developed the
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