3D Geospatial Information Modelling with CityGML

Transcription

1 Technische Universität Berlin 3D Geospatial Information Modelling with CityGML Prof. Dr. Thomas H. Kolbe Institute for Geodesy and Geoinformation Science Berlin University of Technology 18th of January, 2007

2 Topics Spatial Information Modelling CityGML overview, background, and specific details Levels of Detail Thematic Model Generalization support, explicit linking, object history CityGML along the data qualification / processing chain Application Domain Specific Extensions to CityGML CityGML Noise ADE for EC Environmental Noise Directive Status and perspectives 2 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

3 Spatial Information Modelling Current paradigm shift in spatial modelling: from geometry / graphics oriented models to representation of objects with their properties (among them spatial and graphical ones), structures, and interrelationships Concerning 2D data: long tradition in European cadastres Germany: ALKIS/ATKIS/AFIS (AAA) UK: OS Mastermap Netherlands: Top10NL Concerning 3D data: often seen as being identical with 3D visualizations of the respective region Google Earth [KML], X3D, Adobe 3D PDF, 3D Studio Max However: numerous applications beyond 3D visualization 3 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

4 Applications of Virtual 3D City Models SI, Universität Stuttgart Fa. Conterra IKG, Universität Bonn T-Mobile Rheinmetall Defence Electronics Sony Corporation 4 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

5 Information Modelling on Different Scales Model content, structure, and employed modelling principles depend on Scale Scope (application contexts) Taken from the Homepage of the Helmholtz Research Center Karlsruhe, Karl-Heinz-Häfele 5 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

6 CityGML Modelling Urban Spaces Application independent Topographic Information Model for virtual 3D city models comprises different thematic areas (buildings, vegetation, water, terrain, traffic etc.) realized as GML3 application schema Ongoing standardisation process in OGC CityGML represents 3D geometry, 3D topology, semantics and appearance in 5 discrete scales (Levels of Detail, LOD) DEMs in a flexible way (raster, TIN, mass points, break lines; arbitrary combinations / nesting possible) 6 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

7 Originator: GDI NRW and the SIG 3D Geodata Infrastructure North Rhine-Westphalia PPP founded in 1999 by the state government more than 100 institutions organized in 6 Special Interest Groups very active in OGC (GML3, WPOS, Gazetteer, Metadata) Special Interest Group 3D (SIG 3D) open group with >70 active members; 3 working groups from industry, government, municipalities and academia participants from all over Germany, Austria, Switzerland, and UK aims: interoperable visualization Web 3D Service and exchange of 3D geodata CityGML 7 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

8 SIG 3D members (excerpt) Municipalities Berlin Hamburg Köln Düsseldorf Bremen Essen Wuppertal Bochum Stuttgart Administration State mapping agencies (DE) Ordn.Survey UK Companies T-Mobile Bayer Industry Services Rheinmetall Defence 3D Geo CPA Geoinformation Con Terra GIStec GTA Geoinformatik Inpho Citygrid (AT) CyberCity (CH) Snowflake (UK) Science Univ. of Bonn Univ. of Hamburg Univ. of Potsdam Univ. of Hannover Univ. of Dortmund Univ. of Münster Fraunhofer Institute for Computer Graphics, Darmstadt Helmholtz Research Center Karlsruhe Univ. of Applied Sciences Stuttgart 8 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

9 Goals of CityGML (I) Establish high degree of semantic (and syntactic) interoperability enabling multifunctional usage of 3D city models definition of a common information model 3D geo base data (in the tradition of most European 2D digital landscape models, cadastre models) Representation of 3D topography as observed explicit 3D shapes; mainly surfaces & volumes identification of most relevant feature types usable in a wide variety of applications limited inclusion of functional aspects in base model 9 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

10 Goals of CityGML (II) Suitability for Spatial Data Infrastructures mapping to appropriate exchange format -> GML3 needs high degree of expressivity wrt. OO models must be usable in the context of OGC Web Services possibility to link any CityGML feature to more specialised, functional models / external data sources Must be simple to use for applications well-defined semantics for feature types; however semantic structure not too fine-grained subset of GML3 geometries (no curved lines, surfaces) Boundary representation with absolute coordinates advantage: directly manageable within 3D GIS / geo DB 10 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

11 Multiple Usages of City Models Information preserving and adding data exchange along the processing / value adding chain Modelling requirements modelling of geo-objects ( features ), not only 3D geometry and graphical appearance Application independent base classes and attributes flexibility wrt. geometrical, topological and structural qualities of concrete realizations of 3D city models System independent and standards based modelling Application specific extendibility, e.g. for Real estate management, noise immission mapping Business models, legal frameworks 11 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

12 Multi-scale modelling: 5 level of details LOD 0 Regional model 2.5D Digital Terrain Model LOD 1 City / Site model block model w/o roof structures LOD 2 City / Site model textured, differenciated roof structures LOD 3 City / Site model detailed architecture model LOD 4 Interior model walkable architecture models 12 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

13 Thematic Modelling in CityGML <<FeatureCollection>> CityModel * <<Feature>> _CityObject * ExternalReference - informationsystem: anyuri - externalreference: ExternalObjectReferenceType _Transportation Objects _City Furniture CityObject Group _Water Bodies _Site Complex Relief lod1geometryproperty lod2geometryproperty Geometry _Vegetation lod3geometryproperty 13 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

14 Spatio-semantical Composition 3D-Modell: Stadt Coburg BuildingInstallation (Dormer) BuildingPart Building BuildingPart Building Building surface (WallSurface) 14 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

15 Example: Building Model in Level of Detail 3 3D-Modell: Dr. Benner, Forschungszentrum Karlsruhe 15 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

16 16 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

17 Further CityGML Concepts Support for generalization of 3D data Generalized objects are linked to the original objects on the larger scale Explicit linking Every CityGML object can have an arbitrary number of links to external resources (files, objects, database entries) Object history Same mechanism as with ALKIS / ATKIS / AFIS Objects may have a lifespan (incl. termination date) Support for spatial homogenization / integration e.g. Terrain Intersection Curves (for integration of 3D objects with the terrain) 17 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

18 CityGML along the Processing Chain Users of virtual 3D city models / Clients from application domains Surveyers / Photogram. Mapping agencies Integrators / Brokers Application user Application end user Registration Continuation Qualification Refinement/ Integration Qualification / Integration for applicat. Specific Application 2D + 2.5D geobase data 3D GIS 3D Geo-DB 3D GIS 3D Geo-DB Application database possibly iterated Added value 18 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

19 Problems along the Processing Chain Diverse qualities of 3D models in the different steps different degree of fidelity of geometry, topology, graphical appearance from simple structured objects to complex application models Until now: often change of data models and exchange formats inbetween the processing steps loss of data because of limited modeling powers of models and formats difficult preservation of object identities Missing back links / references to original data of preceding processes causes problems with updates / continuations 19 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

20 Application Specific Extensions to CityGML CityGML should be considered a base information model for virtual 3D city models But: Specific applications need specific extra information typically in close interaction with CityGML base information Examples Environmental simulations like noise immission mapping need information about noise absorption of surfaces Cultural heritage needs to augment objects by their heritage and history, and has to consider the development along time Utility networks need to represent pipes, pipe tunnels, connectors, transforming devices 20 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

21 Application Domain Extensions (ADE) NoiseSimul. Disaster management... CityGML AAA // NAS... GML XML 21 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

22 Application Domain Extensions (ADE) Types of domain specific extensions: Extension of existing CityGML feature types by additional spatial and non-spatial attributes additional relations / associations Definition of new feature types preferably based on CityGML abstract base class CityObject General considerations: minimal invasive wrt. current CityGML structure for each geometry attribute the LOD has to be indicated in the element name, e.g. lod2multicurve or lod3surface multiple LODs: similar realization as CityGML core feature types 22 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

23 CityGML ADE Design Decisions must remain valid CityGML pure" CityGML reader overread application specific data fixed XML application schema for each specific application can be used to validate the XML data files no new subclasses in case of attribute extensions many systems typically do not recognize, that they are dealing with subclasses (no XML schema awareness) instead: extension of CityGML classes, e.g. Building designer and users of domain specific extensions must be able to associate new attributes to concrete CityGML feature types E.g. no BuildingInhabitants for SolitaryVegetationObjects 23 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

24 Application of CityGML for Noise Mapping Besides the scenario and the implementations within the OGC Testbed OWS-4, CityGML is applied in a big ongoing project in Germany: Usage of CityGML for the computation of the noise immission maps in the state North Rhine-Westphalia Background: Environmental Noise Directive from the European Commission System Architecture (using the GDI NRW), Web Services: WFS, WMS; Data formats: ATKIS, CityGML Estimated savings (wrt. proprietary systems): >10 Mio Extension of CityGML by noise relevant attributes and features: CityGML Noise ADE 24 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

25 Application Domain Extensions (ADE) Extension of the CityGML XML Schema declarations: <xsd:complextype name=building > <xsd:element ref="_genericapplicationpropertyofbuilding" minoccurs="0" maxoccurs="unbounded"/> </xsd:complextype> <xs:element name="_genericapplicationpropertyofbuilding" abstract="true" type="xs:anytype"/> will allow to inject further XML structures into CityGML feature types at a later point in time (hooks for ADEs). one hook for each CityGML feature type 25 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

26 Application Domain Extensions (ADE) Declaration of application domain specific attributes for existing CityGML features (e.g. Building, XML schema): <xsd:element name="noisereflection" type="xsd:string" substitutiongroup= "citygml:_genericapplicationpropertyofbuilding"> </xsd:element> <xsd:element name="buildinghabitants" type="xsd:positiveinteger" substitutiongroup= "citygml:_genericapplicationpropertyofbuilding"> </xsd:element> 26 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

27 Application Domain Extensions (ADE) Example for a CityGML Building feature with application specific extra information (qualified by a namespace): <Building> </Building> <function>1000</function> <noise:noisereflection>12</noise:buildingreflection> <noise:buildinghabitants>8</noise:buildinghabitants>... <lod2solid> </lod2solid> 27 T. H. Kolbe 3D Geospatial Information Modelling with CityGML

28 Status and Roadmap Current status: Discussion Paper (OGC ) Next step: OGC Best Practice Paper Best Practice Paper represents an official standpoint of the OGC Envisaged timeline: OGC TC July 2007 meeting in Paris Adoption as an International Standard planned for December 07 Harmonization with IFC Continuation of the discussion started in Summer 2006 Status: set of rules for conversion IFC->CityGML Aim: CityGML->IFC, Conversion Specification (mutual document from IAI and OGC) Discussion about linkage to GoogleEarth 28 T. H. Kolbe 3D Geospatial Information Modelling with CityGML