ABSTRACT
The OGC adopted the ISO 19107 international standard83 as Topic 1 of the Abstract Specifications: Feature Geometry.144 These Abstract Specifications provide conceptual schemas for describing the spatial characteristics of spatial objects (geographic or spatial features, in OGC terms) with vector geometry and topology up to three dimensions embedded in 3D space. The Abstract Specifications also describe a set of spatial operations consistent with these schemas. According to the specifications, the spatial object is represented by two structures: (1) structure of geometrical primitives (i.e., simple feature) and (2) topological structure (i.e., complex feature). While the geometrical structure provides direct access to the coordinates of individual objects, the topological structure encapsulates information about their spatial relationships.
