Introduction to PostGIS

36. Appendix B: Glossary

CRS
A “coordinate reference system”. The combination of a geographic coordinate system and a projected coordinate system.
GDAL
Geospatial Data Abstraction Library, pronounced “GOO-duhl”, an open source raster access library with support for a large number of formats, used widely in both open source and proprietary software.
GeoJSON
“Javascript Object Notation”, a text format that is very fast to parse in Javascript virtual machines. In spatial, the extended specification for GeoJSON is commonly used.
GIS
Geographic information system or geographical information system captures, stores, analyzes, manages, and presents data that is linked to location.
GML
Geography Markup Language. GML is the OGC standard XML format for representing spatial feature information.
JSON
Javascript Object Notation”, a text format that is very fast to parse in Javascript virtual machines. In spatial, the extended specification for GeoJSON is commonly used.
JSTL
“JavaServer Page Template Library”, a tag library for JSP that encapsulates many of the standard functions handled in JSP (database queries, iteration, conditionals) into a terse syntax.
JSP
“JavaServer Pages” a scripting system for Java server applications that allows the interleaving of markup and Java procedural code.
KML
“Keyhole Markup Language”, the spatial XML format used by Google Earth. Google Earth was originally written by a company named “Keyhole”, hence the (now obscure) reference in the name.
OGC
The Open Geospatial Consortium (OGC) is a standards organization that develops specifications for geospatial services.
OSGeo
The Open Source Geospatial Foundation (OSGeo) is a non-profit foundation dedicated to the promotion and support of open source geospatial software.
SFSQL
The Simple Features for SQL (SFSQL) specification from the OGC defines the types and functions that make up a standard spatial database.
SLD
The Styled Layer Descriptor (SLD) specification from the OGC defines an format for describing cartographic rendering of vector features.
SRID
“Spatial reference ID” a unique number assigned to a particular “coordinate reference system”. The PostGIS table spatial_ref_sys contains a large collection of well-known srid values and text representations of the coordinate reference systems.
SQL
Structured query language” is the standard means for querying relational databases.
SQL/MM
SQL Multimedia; includes several sections on extended types, including a substantial section on spatial types.
SVG
Scalable vector graphics” is a family of specifications of an XML-based file format for describing two-dimensional vector graphics, both static and dynamic (i.e. interactive or animated).
WFS
The Web Feature Service (WFS) specification from the OGC defines an interface for reading and writing geographic features across the web.
WMS
The Web Map Service (WMS) specification from the OGC defines an interface for requesting rendered map images across the web.
WKB
“Well-known binary”. Refers to the binary representation of geometries described in the Simple Features for SQL specification (SFSQL).
WKT
Well-known text”. Can refer either to the text representation of geometries, with strings starting “POINT”, “LINESTRING”, “POLYGON”, etc. Or can refer to the text representation of a CRS, with strings starting “PROJCS”, “GEOGCS”, etc. Well-known text representations are OGC standards, but do not have their own specification documents. The first descriptions of WKT (for geometries and for CRS) appeared in the SFSQL 1.0 specification.


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