Simple Features
Encyclopedia
Simple feature access is both an OpenGIS
and ISO
Standard that specifies a common storage model of geographical data (point, line, polygon, multi-point, multi-line, etc.) using well-known text
(or binary). The geometries are also associated with spatial reference systems. The SFA also specifies attributes
, methods
and assertions
with the geometries.
In general, a 2D geometry is simple if it contains no self-intersection. The SFA specification defines DE-9IM
spatial predicates and several spatial operators that can be used to generate new geometries from existing geometries.
Open Geospatial Consortium
The Open Geospatial Consortium , an international voluntary consensus standards organization, originated in 1994. In the OGC, more than 400 commercial, governmental, nonprofit and research organizations worldwide collaborate in a consensus process encouraging development and implementation of open...
and ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
Standard that specifies a common storage model of geographical data (point, line, polygon, multi-point, multi-line, etc.) using well-known text
Well-known text
Well-known text is a text markup language for representing vector geometry objects on a map, spatial reference systems of spatial objects and transformations between spatial reference systems. A binary equivalent, known as well-known binary is used to transfer and store the same information on...
(or binary). The geometries are also associated with spatial reference systems. The SFA also specifies attributes
Attribute (computing)
In computing, an attribute is a specification that defines a property of an object, element, or file. It may also refer to or set the specific value for a given instance of such....
, methods
Method (computer programming)
In object-oriented programming, a method is a subroutine associated with a class. Methods define the behavior to be exhibited by instances of the associated class at program run time...
and assertions
Assertion (computing)
In computer programming, an assertion is a predicate placed in a program to indicate that the developer thinks that the predicate is always true at that place.For example, the following code contains two assertions:...
with the geometries.
In general, a 2D geometry is simple if it contains no self-intersection. The SFA specification defines DE-9IM
DE-9IM
In geometry, a dimensionally extended nine-intersection model is a topological model used to describe the spatial relation of two geometries in two-dimensions...
spatial predicates and several spatial operators that can be used to generate new geometries from existing geometries.
External links
- OpenGIS Specifications (Standards)
- OpenGIS Simple Features Specification for CORBA (99-054)
- OpenGIS Simple Features Specification for OLE/COM (99-050)
- OpenGIS Simple Features Specification for SQL (99-054, 05-134, 06-104r3)
- OGR - OGR library which implements relevant OGC standards
- OpenGIS Simple Features Specifications For SQL
- MySQL 5.1 documentation on Spatial extensions
- PostGIS Simple Features implementation for PostgreSQL