Transcript The Open GIS Consortium Geog 516 Presentation #2

The OpenGIS Consortium
Geog 516 Presentation #2
Rueben Schulz
March 2004
Overview
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The OpenGIS Consortium
Specifications
Benefits
Issues
Impact and Examples
The OpenGIS Consortium
• Non-profit trade association (1994)
• Develop geoprocessing interoperability
standards
• Grew out of interoperability initiatives in the
GRASS community
• 257 Members, include:
– Government
– Industry
– Universities
• Similar to W3C and ISO
Vision
“A world in which everyone benefits from
geographic information and services made
available across any network, application, or
platform.”
Specifications
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Simple Features (Vectors)
Grid Coverages (Rasters)
Coordinate Transformation Services (CTS)
Geography Markup Language (GML)
Filter Encodings
Styled Layer Descriptor (SLD)
Web Map Services (WMS)
Web Feature Service (WFS)
Web Coverage Service (WCS)
Web Map Context Documents
Catalogue Interface (CAT)
Location Services
Simple Features (Vector)
• Specification currently version 1.1
– Defines a set of basic geometry types:
• Point, line, polygon, multi-point, multi-line, multi-polygon,
multi-geometry
– Defines operations on these
– Includes ways of storing geometries and features
• WKT, WKB, GML
• Work on a new abstract specification
– ISO-19107 (an ISO partnership)
– Lots of different geometries (not simple)
• 3D shapes, surfaces, TINs, and many more
Simple Features Con’t
Grid Coverages (Raster)
• Defines interfaces for:
– accessing, analyzing and processing raster
datasets
• Grid coverage can generate a value for
any point in its domain.
• May be backed by a:
– Set of polygons that cover entire area
– Grid of values (traditional raster)
– Mathematical function
Coordinate Transformations
• Describes Coordinate Reference System‘s (CRS) and
general methods to convert between them.
• Also specifies ways of storing these objects as text
– Well Known Text (WKT) and XML
– WKT example:
GEOGCS["WGS 84", DATUM["WGS_1984",SPHEROID["WGS
84",6378137,298.257223563],TOWGS84[0,0,0,0,0,0,0],
PRIMEM["23W",23],UNIT["DMSH",0.0174532925199433],
AXIS["Long",EAST],AXIS["Lat",NORTH]]
• Compliments efforts by European Petroleum Survey
Group (EPSG)
• New specification underway (ISO – 19111)
Web GIS Standards
• Standard protocols for:
– Web Map Services (WMS)
• Sends images of maps across the web
• Useful for base maps, but does not give access to underlying
data
– Web Feature Service (WFS)
• Sends vector geometries (GML), can do analysis / editing on
these
– Web Coverage Service (WCS)
• Sends rasters (grid coverage), can do analysis on these
Benefits
• Users can easily move between vendors
– Data interchange
– Concepts about GIS/RS the same; single set of terms
and definitions
• Efficient and share R&D - best minds from many
different industries can meet and work.
• Document ideas for other people to learn from
• Can advance state of the art or increase
completeness of a product
• Increase competition and innovation
Issues
• Specifications need to be implemented to be of
any benefit
– Vendors have products implemented before
specification
– Specification may need to be extended in
incompatible ways to do everything vendor wants now
• Bad for large companies
– Makes it easier for users to change vendors
– Removes some competitive advantage
• Specifications keep changing
Impact and Examples
• US Geospatial 1 Stop Portal - WMS, WFS, CAT
• Canadian GeoConnections Discovery Portal - WMS, WFS, CAT
• ESRI’s ArcGIS - Simple Features, Spatial References
– OGC Imperoperability Addon to support GML, WMS, WFS
• PostGIS, ArcSDE, Oracle Spatial, and IBM DB2 - support Simple
Features for SQL
• Java Topology Suite (JTS) – Simple Features
• GeoTools2 – “leading open source Java library for developing
OpenGIS solutions”
• MapServer – WMS
• GeoServer – WMS and reference implementation for WFS
• ESRI’s ArcIMS - WMS and WFS through an addon
Impact and Examples con’t
References
• DigitalEarth.Org “OGC December Meeting Summary” at
http://digitalearth.org/story/2002/12/12/143552/20
• ESRI “GIS Standards and Interoperability” at
http://www.esri.com/software/opengis/index.html
• Federal Computer Week "Interior e-gov tack irks GIS
vendors: GIS Consortium, vendor work on parallel tasks“
at http://www.fcw.com/fcw/articles/2003/0414/news-gis04-14-03.asp
• The OpenGIS Consortium at http://www.opengis.org