Geography Markup Language Digital Geographic Information Working Group Conference Vancouver, 09 April, 2003 Milan Trninić

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference Galdos Systems A young, fast moving software company focused on XML and Web-Services for Geo-spatial information systems Ron Lake, the owner and CEO was founding member of OGC (1993). Creator of Geography Markup Language. Lead participant in OGC standards efforts including GML, WFS, WCS since Expertise in Analysis/Design/Build, GML Application Schema development, XML Applications (XSD / XML / SVG / XSLT / SOAP / WSDL etc.), Java client/server side development (J2ME J2EE), OGC & ISO TC/211 TC204 Standards

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML History Feb 99 – White paper by Galdos on XML for spatial. Feb 99 – Presentation by NTT Data Summer 99 – Xbed Group led by Galdos Systems, develops SFXML (Oracle, NTT Data, MapInfo) October 99 – Galdos Systems writes GML RFC, in December it becomes public May 2000 – GML 1.0 Passed as recommendation paper. Feb 2001 – OGC publishes GML 2.0 March 2001 – GML 2.0 voted as adopted specification July 2001 – GML 3.0 Workshop in Vancouver 2001 – Work on GML3.0 in progress. Work on harmonizing G-XML and GML3.0 in progress. Sept 2001 – OGC votes to send GML to ISO 2002 – Work on GML3.0 in progress February 2003 – OGC releases GML3.0 Specification

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Overview What is it? OGC Endorsed Adopted Specification. A lingua franca for geographic information. XML technology for handling spatial data on the Internet. Emerging international standard for spatial data endorsed by companies and agencies around the world. Converged with G-XML (Japan) – additional 600 companies.

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Overview What is it? Data transport Data modeling language - build application vocabularies for specific domains. Create types for geo-spatial web service Data store model. Links between elements can exist across the Internet. Links can represent relationships (e.g. spatial)

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Overview GML focuses on content and separates content and presentation GML data can be read and understood by people. Easily transformed. GML can enable distributed spatial datasets that are linked together – local maintenance & development /global access. Reduced cost for data GML data can easily be mixed with non-spatial data including text, video, and imagery. GML can build shareable application schemas for various applications like telecommunications, utilities, forestry, tourism, location-based services, etc. Enables creation and easy discovery of typed services. Provides a standard means to define input & output arguments. GML is non-proprietary and open! Enables non-proprietary web feature servers, image/map annotation, map styling, spatial analysis, etc.

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Overview Major elements of GML Feature model Geometry (2D, 2.5D, 3D) Topology Coverage Presentation - styling Coordinate Reference Systems Units Of Measure Meta data Dictionaries Temporal (moving objects) Observations

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Feature Model Developed in GML2.0 Based on OGC Abstract Specification Feature model of ISO matches GML (GML is a subset). Enables complex features & feature associations

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Feature Model Properties … KCFL Property of a feature describes its role in the feature

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Feature Model Properties … Value Property value can be inline Property value can be remote = Value =

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Geometry ISO compliant 0D, 1D (linear, arcs, bezier, splines), 2D 2.5D Geometries (2D in 3D), 3D (solids with holes) Geometry Aggregates and Geometry Complexes Robson 49.29, ,

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Geometry Robson >49.29, , >49.285, ,

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Topology ISO compliant Nodes, Edges, Faces and Solids Topological complexes Topology can be described as a part of a feature or outside of features (e.g. topology of all city streets)

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Topology......

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Geometry and Topology GML

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Coverage ISO compliant A coverage is a GML feature Gridded coverage, segmented curves, surface tessellation Data can be binary (file), Comma Separated Values (CSV), XML Easy to express things like distribution of measurement (temperature, pressure) over some geographic region.

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Temporal Model ISO compliant Covers most of the temporal types from the ISO Support for dynamic feature (jointly feature and temporal model) Supports the notion of History Time stamping on feature or property level

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Meta Data

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Default Styling Focuses on feature styling Uses Scalable Vector Graphics (SVG) and Cascading Style Sheet 2 directly Capability to define styles for feature properties of different kinds Geometry styling and topology styling Ability to describe animation styles Parameterized styles – the output depends on values of feature properties

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Default Styling Symbol Libraries Symbol Libraries – created separately and used in GML styles Online Symbol Library (XML) Inline symbol definition using SVG and CSS2

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Default Styling and SLD Styled Layer Description – an OGC specification SLD has different scope – describes layers and layer styles – pertains to WMS GML styling mechanism describes feature styles – can be used in any application that uses GML Efforts under way to harmonize GML Styling and SLD

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Coordinate Reference Systems Emerged from work done in OGC CRS WG and GML3.0 WG Complete schemas for description of all aspects of CRS (SRS) Definitions also exist for accuracy, data quality, units of measure etc. CRS defined in form of libraries and used from various applications, or referred to from the GML data directly

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Coordinate Reference Systems 49.29, , EPSG 6/2/1995 WGS 84 Used by the GPS satellite navigation system and for NATO military geodetic surveying. Online CRS Registry

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML and ISO GML 3.0 is the baseline for ISO GML. We do not expect major changes in GML in order for GML to become an ISO specification (ISO 19136) There are no serious compliance issues - a joint meeting (ISO and OGC) was held in Annapolis and this was discussed at length OGC and ISO have agreed to create an integrated task force and produce a single specification Joint task force to meet in May and likely also in Vancouver in July. We anticipate GML will be an ISO DIS by Dec 2003 or Jan 2004.

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Performance

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Applications

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Future

Vancouver, April 09, 2003 Digital Geographic Information Working Group Conference GML Notes GML Dev Days in Vancouver, July 2003 First book on GML: GML Guide presently in print