The OpenGIS Consortium Geog 516 Presentation #2 Rueben Schulz March 2004

Overview 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 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 (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", , ],TOWGS84[0,0,0,0,0,0,0], PRIMEM["23W",23],UNIT["DMSH", ], 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 ESRI “GIS Standards and Interoperability” at Federal Computer Week "Interior e-gov tack irks GIS vendors: GIS Consortium, vendor work on parallel tasks“ at asphttp:// asp The OpenGIS Consortium at