OGC Simple Features

OGC Simple Features
Name	OGC Simple Features
Developer	Open Geospatial Consortium
Released	1999
Latest release	2011 (ISO/OGC harmonization)
Platform	Cross-platform
License	Various (open standards)

OGC Simple Features

OGC Simple Features are a set of standardized geometric object models and interfaces devised by the Open Geospatial Consortium that define how Geographic Information Systems encode, store, and query planar geometries; these models influenced implementations across vendors such as ESRI, Oracle Corporation, PostGIS, Microsoft, and IBM. The model establishes interoperable representations for points, linestrings, polygons and collections used by projects from Google Maps to OpenStreetMap and in standards work with International Organization for Standardization, ISO/TC 211, and datasets produced by agencies like United States Geological Survey and Ordnance Survey. Adoption of the specification underpinned features in products from QGIS and libraries such as GEOS, GDAL, and PROJ, and shaped query behavior in systems including MySQL, SQLite, and PostgreSQL.

Overview

The Simple Features specification originated as a community-driven effort led by the Open Geospatial Consortium and was harmonized with ISO 19125 to produce a normative model for spatial data exchange used by agencies such as National Aeronautics and Space Administration, European Space Agency, United Nations, and firms like Apple Inc., Amazon (company), Microsoft Corporation. It prescribes geometric primitives and topological rules adopted in formats like Well-Known Text, Well-Known Binary, and influenced operations in services such as Web Map Service and Web Feature Service. Implementers from Esri to FOSS4G projects rely on the specification to ensure interoperability between platforms including ArcGIS, GeoServer, MapServer, and cloud offerings from Google Cloud Platform and Amazon Web Services.

Geometry Types and Representations

Simple Features defines primitive and composite types: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection, with representations expressed in Well-Known Text and Well-Known Binary; these encodings are widely used by tools like GDAL/OGR, GEOS, JTS Topology Suite, and databases such as PostGIS and Oracle Spatial. The specification clarifies interior and exterior ring order conventions used by authorities like US Census Bureau and Natural Resources Canada and influenced formats such as Shapefile and GeoJSON; software stacks including Leaflet (software), OpenLayers, Mapbox, and Cesium (software) consume these representations. Topological predicates and operations (e.g., intersects, contains, touches) align with implementations in JTS and libraries wrapped for languages like Python (programming language), Java (programming language), C++,R (programming language), and JavaScript.

Coordinate Reference Systems and Precision

The specification separates geometry types from coordinate reference systems, encouraging explicit CRS metadata compatible with EPSG codes from the European Petroleum Survey Group legacy maintained by OGC and EPSG Geodetic Parameter Registry; implementations support reprojection via libraries such as PROJ and services provided by agencies like Ordnance Survey and National Geospatial-Intelligence Agency. Precision, dimensionality (2D, 3D, measured), and coordinate ordering issues appear in guidance from ISO/TC 211, data producers like NOAA, NASA, USGS, and platform vendors such as Esri and Microsoft Azure; these influences shaped behavior in PostGIS, SpatiaLite, and Oracle Spatial and Graph. Handling of datum transformations and vertical datums intersects work by International Hydrographic Organization and standards bodies including IHO, with best practices used by projects like Copernicus Programme and Landsat processing chains.

SQL and OGC Simple Features Implementation

The Simple Features model was mapped to SQL in the OGC/ISO profile adopted by databases including PostgreSQL, MySQL, SQLite, Oracle Database, and Microsoft SQL Server to provide standardized SQL/MM spatial functions; these mappings enabled spatial indexing strategies like R-tree and GiST used by PostGIS, SpatiaLite, and Oracle Spatial. Common SQL function names (ST_Intersects, ST_Buffer, ST_Union) originate from the specification and are implemented across engines used in enterprise stacks from SAP to Snowflake (computing) and analytic systems such as Apache Hive, Apache Spark, and Presto (SQL query engine). Workflows in platforms from FME (software) to Safe Software and scripting integrations with GDAL/OGR use the SQL profile to enable interoperability between government data portals like data.gov and commercial providers like HERE Technologies and TomTom.

Standards and Versions

Key milestones include the OGC Simple Features Specification for SQL (1999), harmonization with ISO 19125 parts 1 and 2, and updates reflected in the OGC Best Practice documents used by OGC Web Services and profiles for ISO/TC 211; major vendors and organizations such as Esri, Oracle Corporation, PostGIS, MapInfo, Bentley Systems, Autodesk, and Trimble track these versions for compatibility. Parallel standards interacting with Simple Features include OGC Web Feature Service, GeoPackage, CityGML, KML (Keyhole Markup Language), GML, and INSPIRE directives adopted by the European Commission; international bodies such as United Nations Committee of Experts on Global Geospatial Information Management reference Simple Features in capacity-building and data sharing initiatives.

Implementations and Software Support

Implementations span open source and commercial ecosystems: PostGIS (PostgreSQL extension), SpatiaLite (SQLite extension), Oracle Spatial, SQL Server Spatial, MySQL Spatial Extensions, MongoDB geospatial features, ESRI ArcSDE, and middleware like GeoServer and MapServer. Libraries and toolkits include GEOS, JTS Topology Suite, GDAL/OGR, PROJ, PyProj, Shapely (software), and Fiona (software), while client libraries and frameworks such as Leaflet (software), OpenLayers, Mapbox GL JS, Cesium (software), and Deck.gl provide front-end support. Major scientific and mapping projects—from OpenStreetMap to Natural Earth and national cadastres such as HM Land Registry—rely on Simple Features conformance for data interchange, enabling ecosystems across cloud providers like Google Cloud Platform, Amazon Web Services, and Microsoft Azure.

Category:Geographic information systems