CityGML - Modelling our environment

4th of March, 2008

Chair of Methods of Geoinformation ScienceChair of Methods of Geoinformation Science

CityGML - Modelling our environment

Alexandra Stadler, Thomas H. Kolbe

Technische Universität BerlinInstitute for Geodesy and Geoinformation ScienceChair of Methods of Geoinformation Science

4th of March, 2008Alexandra Stadler, Thomas H. Kolbe: CityGML – Modelling our environment

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ContentContent

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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ContentContent


Modularisation




External references

Appearances




Homeland Security



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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

MotivationMotivation


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Standards are the key…Standards are the key…

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

Application

Data source A Data source B


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Never heard about CityGML – what‘s that?Never heard about CityGML – what‘s 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 >70 companies, municiplaities and research

institutions

lead managed by Prof. Thomas Kolbe (IGG TU Berlin)

Dr. Gerhard Gröger (IGG Uni Bonn)


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CityGML‘s way to become an OGC standardCityGML‘s way to become an OGC standard

CityGML 0.4.0OGC Best Practices Paper

CityGML 1.0.0 (Proposal)OGC Request for Comments

CityGML 0.3.0OGC Discussion Paper

2007-05-30

2008-02-04

2006-03-06

2008-02-192008-03-20

CityGML 1.0.0OGC Implementation Specification(after final OGC TC vote)

coming soon

<<<<<<< Public Comment Phase >>>>>>>

International Standard


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ContentContent


Modularisation




External references

Appearances




Homeland Security



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ModularisationModularisation

CityGML consists of the core module several extension modules vertical

subdivision


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Coherence of semantics and geometryCoherence of semantics and geometry

…

Semantic objecte.g. Building

Corresponding geometrye.g. Solid

…

Use of Boundary Representation (B-Rep) for geometry modelling

Explicit relations between semantic objects and their geometrical representations

* *


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GeometrySemantics

KML: No semantics, only (unstructured) geometry

CityGML vs. KMLCityGML vs. KML

CityGML: (Up to) Complex objects with structured geometrySemantics Geometr

y


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„Availability“ of semantics„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 modellingMulti-scale modelling

LOD 4 – Interior model„Walkable“ architectural models

LOD 3 – City / Site modelDetailed architectural model

LOD 2 – City / Site modelExplicit roof structures

LOD 1 – City / Site model„Block model“ without roof structures

LOD 0 – Regional model2.5d Digital Terrain Model


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Terrain intersection curveTerrain 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 referencesExternal 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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AppearancesAppearances

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)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: CityGML+ADE 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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ContentContent


Modularisation




External references

Appearances




Homeland Security



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German cities modelled in CityGMLGerman 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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ImplementationImplementation

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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ConversionConversion

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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ViewerViewer

LandXPlorer (C++) 3D Geo, Potsdam

Hasso-Plattner-Institute(University of Potsdam)

Aristoteles 3D-Viewer (Java) IGG, University of Bonn


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ContentContent


Modularisation




External references

Appearances




Homeland Security



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Target application areasTarget application areas


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Application scenario 1: Noise immision mappingApplication 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 mappingApplication scenario 1: Noise immision mapping

Noise immsion mapsreported to EU

(via WMS service)

Noise immision simulation

3d geodata in CityGMLas input for the

calculaion of noise immision maps


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Application scenario 2: Homeland securityApplication scenario 2: Homeland security

Testbed OWS-4 of the Open Geospatial Consortium (OGC) Setting:

Explosion of a „dirty bomb“ in the New York harbour

Task:Support 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 SecurityApplication scenario 2: Homeland Security

CityGML building visualised using LandExplorer from outside (left)

room-based representation of the security level (right)


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http://www.opengeospatial.org/pub/www/ows4/index.html

Application scenario 2: Homeland SecurityApplication scenario 2: Homeland Security


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ContentContent


Modularisation




External references

Appearances




Homeland Security



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CityGML code example: Building in LOD 3CityGML code example: Building in LOD 3

<?xml version="1.0" encoding="UTF-8"?>

<CityModel xmlns="http://www.opengis.net/citygml/1.0" xmlns:bldg="http://www.opengis.net/citygml/building/1.0"

xmlns:gml="http://www.opengis.net/gml" xmlns:xlink="http://www.w3.org/1999/xlink"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://www.opengis.net/citygml/building/1.0 ../CityGML/building.xsd">

<gml:description>This 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”)</gml:description>

<gml:name>IFC_Building_Variant</gml:name>

<gml:boundedBy>

<gml:Envelope srsName="urn:ogc:def:crs,crs:EPSG:6.12:31467,crs:EPSG:6.12:5783">

<gml:pos srsDimension="3">5429999.751795 3449999.751795 0.0</gml:pos>

<gml:pos srsDimension="3">5430023.2 3450021.2 20.0</gml:pos>

</gml:Envelope>

</gml:boundedBy>

…

<cityObjectMember>

<bldg:Building gml:id="GEB_TH_IFC_Building_Variant_GEB_75">

<gml:description>Building in LOD 3</gml:description>

<gml:name>Building-ADT-2006</gml:name>

<externalReference>

<informationSystem>http://www.iai.fzk.de/raw/pages/german/projekte/VR-Systeme/html/Download/

</informationSystem>

<externalObject>

<uri>urn:ifc:oid:0deJpNQ05BvwV03c405oVp</uri>

</externalObject>

</externalReference>


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<bldg:boundedBy>

<bldg:RoofSurface gml:id="GEB_TH_IFC_Building_Variant_DACH_136">

<externalReference>

<informationSystem>http://www.iai.fzk.de/raw/pages/german/projekte/ VR-Systeme/html/Download/</informationSystem>

<externalObject>

<uri>urn:ifc:oid:3CPSkwS7f9QRfhfr5gf7dq</uri>

</externalObject>


<bldg:lod3MultiSurface>

<gml:MultiSurface>

<gml:surfaceMember>

<gml:Polygon>

<gml:exterior>

<gml:LinearRing>

<gml:posList srsDimension="3">5430006.994499969 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 9.141580054626465</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Polygon>

</gml:surfaceMember>

<gml:surfaceMember>

<gml:Polygon>

<gml:exterior>

<gml:LinearRing>


</gml:LinearRing>

</gml:exterior>

</gml:Polygon>


…


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</gml:MultiSurface>

</bldg:lod3MultiSurface>

</bldg:RoofSurface>

</bldg:boundedBy>

<bldg:boundedBy>

<bldg:WallSurface gml:id="GEB_TH_IFC_Building_Variant_WAND_78">

<externalReference>

<informationSystem>http://www.iai.fzk.de/raw/pages/german/projekte/ VR-Systeme/html/Download/</informationSystem>

<externalObject>

<uri>urn:ifc:oid:2es$8LnAD9UxRIGzY8UaVK</uri>

</externalObject>



<gml:MultiSurface>

<gml:surfaceMember>

<gml:Polygon>

<gml:exterior>

<gml:LinearRing>

<gml:posList srsDimension="3">5429999.999999809 3450004.4950001715 6.0599999968 5429999.999999809 3450004.4950001715 4.800000021324157 5430000.119999695 3450004.4950001715 4.800000021324157 5430000.180000114 3450004.4950001715 4.800000021324157 5430000.3 3450004.4950001715 4.800000021324157 5430000.3 3450004.4950001715 6.059999996886253 5430000.180000114 3450004.4950001715 6.059999996886253 5430000.119999695 3450004.4950001715 6.059999996886253 5429999.999999809 3450004.4950001715 6.059999996886253</gml:posList>

</gml:LinearRing>

</gml:exterior>

</gml:Polygon>


…

</gml:MultiSurface>



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<bldg:opening>

<bldg:Window gml:id="GEB_TH_IFC_Building_Variant_OEFF_OBJ_80">

<externalReference>

<informationSystem>http://www.iai.fzk.de/raw/pages/ german/projekte/VR-Systeme/html/Download/ </informationSystem>

<externalObject>

<uri>urn:ifc:oid:3VkZRUoa97GgMdD342zHck</uri>

</externalObject>



<gml:MultiSurface>

<gml:surfaceMember>

<gml:Polygon>

<gml:exterior>

<gml:LinearRing>


</gml:LinearRing>

</gml:exterior>

</gml:Polygon>


…

</gml:MultiSurface>


</bldg:Window>

</bldg:opening>

…

</bldg:WallSurface>

</bldg:boundedBy>

</bldg:Building>

</cityObjectMember>

</CityModel>


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Search the web for further examples… e.g.Search the web for further examples… e.g.

http://www.iai.fzk.de/www-extern/index.php?id=1412


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Search the web for further examples… e.g.Search the web for further examples… e.g.

http://www.iai.fzk.de/www-extern/index.php?id=1470


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Thank you…Thank you…

One thing we would really like to know:

What do YOU think about CityGML?

CONTACT INFORMATIONProf. Dr. Thomas H. Kolbe, Claus Nagel, Alexandra Stadler

{ kolbe | nagel | stadler } @ igg.tu-berlin.de

Technische Universität BerlinInstitute for Geodesy and Geoinformation Science

Chair of Methods of Geoinformation Science

CityGML - Modelling our environment

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