42. 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.
