GML Geography Markup Language Ron Lake Galdos Systems Inc www'galdosinc'com

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GML Geography Markup LanguageRon
LakeGaldos Systems Incwww.galdosinc.com
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Motivation

• Initiated development with the OGC WMT
• How far can we go with emerging Internet
  standards for spatial information representation,
  visualization and analysis ?

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Internet Standards

• XML V1.0
• XSLT
• SVG
• VML
• XLink/XPointer
• RDF (metadata situations)
• OML (semantics)

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GML

• An XML Encoding
• for
• Geographic Data

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XML Encoding of Geography

• Encoding of Geometry
• Encoding of Feature Property Lists
• Encoding of Spatial Reference Systems

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Separation of Presentation and Content
ltFeature fid"1" featureType"pond"gt
ltDescriptiongtsmall pondlt/Descriptiongt ltPolygon
GeometryID"2" SRS_Name4336" NumRings"1"gt
ltLRinggt ltCList dimension"2"gt0.6,1.5 0.5,0.5
1.0,0.7 1.5,1.5lt/CListgt lt/LRinggt
lt/Polygongt lt/Featuregt
XSLT, or other Style Engine
Geographic data
a map
Style Sheet
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Separation of Graphics Geography

• GML Encodes Geography
• SVG/VML/X3D for Graphics

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Using XSL and SVG
SVG Plug-in or Active-X Control
XSLT Style Sheet
SVG
XSLT Engine
XML Parser
GML Data
Standard Web Browser
Galdos demo 1
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GML is Easy to Transform

• Use of XSLT and Extension Functions for Spatial
  Transformations
• Coordinate Transformation Service

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Flexible Data Transformation
Requestor (client)
Data Source and Transform Request
Transformed XML
XSLT Servlet
XML
XSLT Sheet
XML Data Store
Illustration of XSLT Engine Enabled Transformation
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GML Futures

• GML Conversion Services
• GML Coordinate Transformation Services
• Xlink/Xpointer GML is much more than data
  encoding!
• XSLT Extension Functions for Spatial Analysis
• GML Spatial Databases
• Extensions to GML for Coverages
• Extensions to GML for Topology

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Other Authors of GML

• Oracle
• MapInfo
• CubeWerx
• Compusult

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OGC Meeting

• Vancouver, Feb 7-11, 2000
• rlake_at_galdosinc.com