CityGML - Modelling our environment

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CityGML - Modelling our environment

• Alexandra Stadler, Thomas H. Kolbe
• Technische Universität Berlin
• Institute for Geodesy and Geoinformation Science
• Chair of Methods of Geoinformation Science

2
Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

3
Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

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Motivation

• Ongoing virtualisationof our environment
• Semantic models of all relevant objects in urban
  space
• Base models include most important feature
  classes and attributes
• Objects may have several geometrical
  representations
• Spatial reference links data of different
  disciplines, since they refer to the same
  physical space
• Initiatives
• Inspire
• EuroSDR

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Standards are the key

• to the integration of (3d geo) data of different
  data sources

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Never heard about CityGML whats that?

• Content
• Modelling of all relevant parts of the virtual
  city according to theirsemantics, geometry,
  topology and appearance
• GML 3 application schema (XML based)
• Data model and exchange format for virtual 3d
  city models
• History
• Developed since 2002 by the Special Interest
  Group 3d (NorthRhine Westphalia, Germany)
• Members from gt70 companies, municiplaities and
  research institutions
• lead managed by
• Prof. Thomas Kolbe (IGG TU Berlin)
• Dr. Gerhard Gröger (IGG Uni Bonn)

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CityGMLs way to become an OGC standard
CityGML 0.3.0OGC Discussion Paper
2006-03-06
CityGML 0.4.0OGC Best Practices Paper
2007-05-30
CityGML 1.0.0 (Proposal)OGC Request for Comments
2008-02-04
2008-02-192008-03-20
ltltltltltltlt Public Comment Phase gtgtgtgtgtgtgt
CityGML 1.0.0OGC Implementation
Specification(after final OGC TC vote)
coming soon
? International Standard
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Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

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Modularisation

• CityGML consists of
• the core module
• several extension modules ? vertical
  subdivision

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Coherence of semantics and geometry

• Use of Boundary Representation (B-Rep) for
  geometry modelling
• Explicit relations between semantic objects and
  their geometrical representations

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CityGML vs. KML
CityGML (Up to) Complex objects with structured
geometry
Semantics
Geometry
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Availability of semantics

• Geometric entities know WHAT they are
• Semantic entities know WHERE they are and what
  their spatial extents are

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Multi-scale modelling
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Terrain intersection curve

• Defines the intersection of an object with the
  terrain
• Applicable to
• Building
• CityFurniture
• GenericCityObject
• Implicitly WaterBody, Transportation, LandUse

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External references

• Objects may
• Refer to their original data sources
• Refer to other external data sources containing
  additional data, e.g.
• Building Link to cadastre, information about
  owners
• Door Link to facility management systems
• Antenna Link to mobile communication databases

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Appearances

• Materials (similar to X3D)
• Textures
• Standard textures (explicit texture coordinates)
• Aerial images (georeferenced)
• Projected photos
• Multiple appearances (themes) per object

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Application Domain Extensions (ADE)

• Specific application schemata (e.g., noise
  immission mapping)
• Extend CityGML model by
• Additional feature classes
• Additional attributes
• Additional relations
• Design remarks
• CityGMLADE files remain valid CityGML
• Pure CityGML readers ignore ADE(unknown
  namespace!)
• Accessible XSD document required for each ADE
• Used for validating corresponding CityGML files

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Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

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German cities modelled in CityGML

• 3d city models based on CityGML
• Berlin
• Dresden
• Stuttgart
• Bonn
• Cologne
• Frankfurt/Main
• whole NRW in LOD 1
• Planned for
• Karlsruhe

Berlin (GoogleEarth)
Stuttgart (SupportGIS)
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Implementation

• Growing awareness of CityGML (particularily in
  the US)
• Discussions with
• Web 3D Consortium
• CTO GoogleEarth
• International Alliance for Interoperability
  (IFC-Standard)
• Selected implementations
• Oracle 11G Spatial
• Bentley Microstation, Onuma Planning System
  (CAAD)
• Feature Manipulation Engine (FME)
• Snowflake Software, lat/lon (Web Feature Service)
• CPA SupportGIS (3d GIS-System)

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Conversion

• CityGML ? FME (con terra)
• IFC ? CityGML (Forschungszentrum Karlsruhe)

original IFC model
CityGML LOD 1
CityGML LOD 2
CityGML LOD 3
CityGML LOD 4
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Viewer

• LandXPlorer (C)
• 3D Geo, Potsdam
• Hasso-Plattner-Institute(University of Potsdam)
• Aristoteles 3D-Viewer (Java)
• IGG, University of Bonn

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Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

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Target application areas
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Application scenario 1 Noise immision mapping

• EU Directive Minimisation of noise immissions
• Calculation of noise immission maps for whole
  North Rhine-Westphalia
• Data provision and exchange via CityGML using web
  services (WFS, WCS, WMS)
• 8.4 million 3d buildings in LOD 1
• 3d street network in LOD 0, with additional noise
  related attributes
• 3d rail network in LOD 0
• 3d noise barriers in LOD 1
• Digital terrain model (10 meter resolution)

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Application scenario 1 Noise immision mapping
Noise immision simulation
Noise immsion mapsreported to EU(via WMS
service)
3d geodata in CityGMLas input for the calculaion
of noise immision maps
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Application scenario 2 Homeland security

• Testbed OWS-4 of the Open Geospatial Consortium
  (OGC)
• Setting Explosion of a dirty bomb in the New
  York harbour
• TaskSupport the planning committee in the
  construction of an emergency hospital
• Find the appropriate location
• Identify best fitting existing building (size,
  room layout, air conditioning for
  decontaminations, etc.)
• Thematic queries visual inspections
• Link different web services and client
  applications
• Data formats CityGML and IFC

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Application scenario 2 Homeland Security

• CityGML building visualised using LandExplorer
• from outside (left)
• room-based representation of the security level
  (right)

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Application scenario 2 Homeland Security
http//www.opengeospatial.org/pub/www/ows4/index.h
tml
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Content

• Introduction to CityGML
• General characteristics
• Modularisation
• Coherence of semantics and geometry
• Multi-Scale modelling
• Terrain Intersection Curve (TIC)
• External references
• Appearances
• Application Domain Extensions (ADE)
• Implementation, Conversion, Viewer
• Target application areas
• Noise immision mapping
• Homeland Security
• CityGML code example Building in LOD 3

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CityGML code example Building in LOD 3

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltCityModel xmlns"http//www.opengis.net/citygml/1
  .0" xmlnsbldg"http//www.opengis.net/citygm
  l/building/1.0"
• xmlnsgml"http//www.opengis.net/gml"
  xmlnsxlink"http//www.w3.org/1999/xlink"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-in
  stance"
• xsischemaLocation"http//www.opengis.net/cit
  ygml/building/1.0 ../CityGML/building.xsd"gt
• ltgmldescriptiongtThis file contains four
  buildings which are automatically converted from
  IFC models. This listing only shows an
  excerpt. The full dataset can be downloaded from
  http//www.citygml.org (example dataset
  for four buildings in LOD3)lt/gmldescriptiongt
• ltgmlnamegtIFC_Building_Variantlt/gmlnamegt
• ltgmlboundedBygt
• ltgmlEnvelope srsName"urnogcdefcrs,crs
  EPSG6.1231467,crsEPSG6.125783"gt
• ltgmlpos srsDimension"3"gt5429999.7517
  95 3449999.751795 0.0lt/gmlposgt
• ltgmlpos srsDimension"3"gt5430023.2
  3450021.2 20.0lt/gmlposgt
• lt/gmlEnvelopegt
• lt/gmlboundedBygt
• ltcityObjectMembergt
• ltbldgBuilding gmlid"GEB_TH_IFC_Building
  _Variant_GEB_75"gt
• ltgmldescriptiongtBuilding in LOD
  3lt/gmldescriptiongt
• ltgmlnamegtBuilding-ADT-2006lt/gmlnamegt
  
• ltexternalReferencegt

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CityGML code example Building in LOD 3

• ltbldgboundedBygt
• ltbldgRoofSurface
  gmlid"GEB_TH_IFC_Building_Variant_DACH_136"gt
• ltexternalReferencegt
• ltinformationSystemgthttp//
  www.iai.fzk.de/raw/pages/german/projekte/
  VR-Systeme/html/Download/lt/info
  rmationSystemgt
• ltexternalObjectgt
• lturigturnifcoid3CPSk
  wS7f9QRfhfr5gf7dqlt/urigt
• lt/externalObjectgt
• lt/externalReferencegt
• ltbldglod3MultiSurfacegt
• ltgmlMultiSurfacegt
• ltgmlsurfaceMembergt
• ltgmlPolygongt
• 
  ltgmlexteriorgt
• 
  ltgmlLinearRinggt
• 
  ltgmlposList srsDimension"3"gt5430006.994499969
  3449999.850802998 9.141580054626465
• 
  5430007.093499946 3449999.7517950004
  8.970100114212036 5430000.906494903
• 
  3449999.7517950004 8.970100114212036
  5430001.005499649 3449999.850802998
• 
  9.141580054626465 5430003.999999809
  3450000.9735459564 11.086200187072754
• 
  5430006.994499969 3449999.850802998
  9.141580054626465lt/gmlposListgt

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CityGML code example Building in LOD 3

• 
  lt/gmlMultiSurfacegt
• lt/bldglod3MultiSurfacegt
• lt/bldgRoofSurfacegt
• lt/bldgboundedBygt
• ltbldgboundedBygt
• ltbldgWallSurface
  gmlid"GEB_TH_IFC_Building_Variant_WAND_78"gt
• ltexternalReferencegt
• ltinformationSystemgthttp//
  www.iai.fzk.de/raw/pages/german/projekte/
  VR-Systeme/html/Download/lt/info
  rmationSystemgt
• ltexternalObjectgt
• lturigturnifcoid2es8
  LnAD9UxRIGzY8UaVKlt/urigt
• lt/externalObjectgt
• lt/externalReferencegt
• ltbldglod3MultiSurfacegt
• ltgmlMultiSurfacegt
• ltgmlsurfaceMembergt
• ltgmlPolygongt
• 
  ltgmlexteriorgt
• 
  ltgmlLinearRinggt
• 
  ltgmlposList srsDimension"3"gt5429999.999999809
  3450004.4950001715 6.0599999968

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CityGML code example Building in LOD 3

• 
  ltbldgopeninggt
• ltbldgWindow
  gmlid"GEB_TH_IFC_Building_Variant_OEFF_OBJ_80"gt
• ltexternalReferencegt
• 
  ltinformationSystemgthttp//www.iai.fzk.de/raw/pages
  /
  german/projekte/VR-Systeme/html/Download/
  lt/informationSystemgt
• ltexternalObjectgt
• 
  lturigturnifcoid3VkZRUoa97GgMdD342zHcklt/urigt
• lt/externalObjectgt
• lt/externalReferencegt
• ltbldglod3MultiSurface
  gt
• 
  ltgmlMultiSurfacegt
• 
  ltgmlsurfaceMembergt
• 
  ltgmlPolygongt
• 
  ltgmlexteriorgt
• 
  ltgmlLinearRinggt
• 
  ltgmlposList srsDimension"3"gt5430000.119999695
  3450008.940000343 2.99999994979
  
  5430000.180000114 3450008.940000343
  2.9999999497985836 5430000.180000114
  
  3450008.940000343 1.920000026092529
  5430000.180000114 5430000.180000114
• 
  1.860000083312988 5430000.119999695
  3450008.940000343 1.860000083312988
• 
  5430000.119999695 3450008.940000343
  2.9999999497985836lt/gmlposListgt
• 
  lt/gmlLinearRinggt
• 
  lt/gmlexteriorgt

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Search the web for further examples e.g.
http//www.iai.fzk.de/www-extern/index.php?id1412
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Search the web for further examples e.g.
http//www.iai.fzk.de/www-extern/index.php?id1470
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Thank you

• One thing we would really like to know
• What do YOU think about CityGML?
• CONTACT INFORMATION
• Prof. Dr. Thomas H. Kolbe, Claus Nagel, Alexandra
  Stadler
• kolbe nagel stadler _at_ igg.tu-berlin.de
• Technische Universität Berlin
• Institute for Geodesy and Geoinformation Science
• Chair of Methods of Geoinformation Science