Current Status and Roadmap of CityGML

Department of Geoinformation Science

Technische Universität Berlin

2011/06/26

Current Status and Roadmap of CityGML

Thomas H. Kolbe

DirectorInstitute for Geodesy and Geoinformation ScienceBerlin University of Technology

[email protected]

26th of June, 2011

Joint ISPRS 3DCMA & 3D GeoInfo Conference Wuhan, China

2011/06/263 T. H. Kolbe – Status and Roadmap of CityGML


Image: Berlin Partner, Google

Queries to a 3D City Model / 3D GIS:• How many buildings, monuments, trees?• How many storeys?• Total sealed area?• From which windows can I see place XY?• What is the total window area of the buildings?• Where are the entrances / exits?• What is the energy demand for heating and electricity?



3D City Modelling

… is far more thanthe 3D visualizationof reality

In fact, the geometryand its appearanceare only one aspectof an entity!

Key issue: Semantic Modelling



Example for a Semantic Building Model

Building

BuildingInstallation (Dormer)

BuildingPart

BuildingPart

Building

Building surface (WallSurface)

3D-Modell: Stadt Coburg



Urban Information Modelling with CityGML

Application independent Geospatial Information Model for semantic 3D city and landscape models

comprises different thematic areas (buildings, vegetation, water, terrain, traffic etc.)

data model (UML) according to ISO 191xx standard family exchange format results from rule-based mapping of the

UML diagrams to a GML3 application schema Adopted OGC standard since 08/2008

CityGML represents 3D geometry, 3D topology, semantics and appearance

in 5 discrete scales (Levels of Detail, LOD)



Multi-scale modelling: 5 levels 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



Modular Structure of CityGML

CityGML Core

OGC GML 3.1.1

Appearance

Generics

Application Domain Extensions (ADE)B

uild

ing

City

Fur

nitu

re

City

Obj

ectG

roup

Land

Use

Rel

ief

Tra

nspo

rtat

ion

Veg

etat

ion

Wat

erB

ody

Tun

nel

Brid

ge …



International Adoption of CityGML

Cities / Municipalitiese.g. nearly all German cities with 3D city models; Rotterdam

(NL), Zurich (CH), Geneva (CH), Vancouver (CA), Paris (FR), Marseille (FR), Istanbul (TR), Kuala Lumpur (MY), Yokohama (JP), Doha (Katar); limited awareness in USA (Boston, Chicago)

Organisationse.g. IGN France, Ordnance Survey UK, State mapping agencies

of Bavaria and North-Rhine Westphalia in Germany, BIMTAS in Istanbul, many Research Institutes and Universities

CityGML is being used as a reference in the European INSPIRE Initiative

INSPIRE Building model is nearly identical to CityGML

The new national 3D standard of The Netherlands will be based on CityGML



Semantic 3D City Model of Berlin

>500,000 buildings were >500,000 buildings were automatically reconstructed automatically reconstructed using 2D building footprints using 2D building footprints from cadastre and airborne from cadastre and airborne LIDAR data. LIDAR data. Textures were automatically Textures were automatically extracted from oblique aerial extracted from oblique aerial images. images. Semantic information is also Semantic information is also transferred from cadastre.transferred from cadastre.www.virtual-berlin.de



New Applications: Solar Potential Analysis

Example: Solar Atlas Berlin Semantic information (here: estimated solar energy production)

is used both to cartographically style the visualization and to provide the values shown in the „information balloons“



3D Visualisation of CityGML Models

One 3D City Model may comprise

(or link) thematicdata from differentapplications

can be stored and exchanged as oneCityGML dataset

Multiple, different visualizations withapplication specific cartographic stylings

KML /COLLADA

KML

KML /COLLADA



3DCityDB – Open Source CityGML Software

Free software to manage and visualize CityGML data:

http://www.3dcitydb.net

3D City Database (new version 2.0.5) SQL scripts, PL/SQL functions for Oracle Spatial 10g R2 and above Comprehensive documentation (incl. mapping of CityGML to relations)

3DCityDB Import/Export Tool (new version 1.3) Executable Java binaries; tested with Windows, MacOS X, Linux Complete source code, comprehensive documentation fast CityGML import/export (supports arbitrary file sizes, even >> 4GB) KML/COLLADA exporter

citygml4j (current version 1.0) Java class library and API for reading and writing CityGML datasets Library files for Java5 and Java6 Source code, comprehensive documentation, tutorials



Simulation of Multi Utility Infrastructures



Energy Atlas: Urban Information Fusion

Thermal Remote Sensing

Utility NetworksHeat Emission

Bild: Hoegner / Stilla, TU München

Solar Potential

Solar Irradiation LOD1

Energy AtlasGeschätzter Energie-verbrauch [kwh/a] Geschätzter Energie-verbrauch [kwh/a]

Heating Energy Requirements



News for Version 1.1



CityGML 1.1 Roadmap

Public Call for Change Requests (CR)17 CRs received which have to be processed by the SWG

Formation of the CityGML 1.1 SWGThe Standards Working Group (SWG) is in charge of all changes of the CityGML specification

26.02.2010

09.12.2009

SWG processes CRsCRs have to be discussed and voted on; draft version of the CityGML 1.1 specification is being created currently

Since March 2010

20.08.2008CityGML 1.0International OGC Encoding Standard

July/August 2011 Request for Comments (RFC)The candidate CityGML 1.1 specification will be reviewed and commented on by the public in a 30-day RFC phase

Release of CityGML 1.1

today

End of 2011 – Beginning of 2012

Final editorial changes based on received comments



Received Change Requests comprise...

New thematic modules for the representation ofBridges and TunnelsWalls in cities

Extensions of existing modulesBuilding module

explicit representation of storeys (as own object class)additional thematic boundary surfaces (OuterCeilingS., OuterFloorS.)LOD 0 representation (roofprint, footprint as 3D Multipolygons)

Generic attributesUnit of measure (e.g. meters, dollars, etc.) can be given for attributesGrouping of generic attributes and relation with a unique namespace

MiscellaneousCompressed archive format for CityGML (like KMZ)Topologic Network Modelnew CityObject attributes relativeToTerrain, relativeToWater



CityGML 1.1 Bridge Model

Similar / coherent structure with the Building modelBridges may be decomposed into BridgeParts

Bridges have Thematic Boundary Surfaces (from LOD2) like WallSurface, RoofSurface, FloorSurface, etc.

Thematic Boundary Surfaces can have openings (from LOD3)

Bridges / BridgeParts can have BridgeInstallations (from LOD2)

in LOD4 they can also have a representation of their interiors given by BridgeRooms and BridgeFurniture

All feature types have thematic attributes (like class, function, and usage)

Terrain Intersection Curves

Bridges and BridgeParts can be further decomposed into BridgeConstructionElements (required for static stability)



Bridge Components

BridgePart

BridgePart

BridgePart BridgeInstallation (here: signalling lamp)

BridgeConstructionElement

BridgeConstructionElement

Bridge



Bridge Model in UML [draft; simplified]

<<Feature>>_AbstractBridge

<<Feature>>_BoundarySurface

<<Feature>>RoofSurface

<<Feature>>WallSurfacee

<<Feature>>ClosureSurface

<<Feature>>BridgeInstallation

<<Feature>>BridgeRoom

<<Feature>>BridgeFurniture

<<Feature>>_Opening

<<Feature>>Window

<<Feature>>Door

<<Feature>>Bridge

<<Feature>>BridgePart

<<Feature>>core::_CityObject

<<Geometry>>gml::_Geometry

<<Object>>core::ImplicitGeometry

<<Feature>>GroundSurface

<<Feature>>BridgeConstructionElement

*

*

consistsOfBridgePart

lod2-4Geometry

*

*

interiorBridgeRoom

lod2-4Geometry

lod3-4Geometry

0..1

* *outerBridgeConstruction

lod1-4Geometry

*

*

boundedBy

*

lod4Geometry

lod3-4Geometry

*

0..1

interiorFurniture

* 0..2opening

*

*

bridgeInstallation

*

*

boundedBy

Visual Paradigm for UML Standard Edition(Technical University Berlin)



Examples for Bridges in LODs 1-4

LOD 1 LOD 2

LOD 3 LOD 4

Models source: Google 3D Warehouse



CityGML 1.1 Tunnel Model

Similar / coherent structure with the Building modelTunnels may be decomposed into TunnelParts

Tunnels have Thematic Boundary Surfaces (from LOD2) like

WallSurface, RoofSurface, GroundSurface, FloorSurface etc.

Thematic Boundary Surfaces can have openings (from LOD3)

Tunnels / TunnelParts can have TunnelInstallations (from LOD2)

in LOD4 they can also have a representation of their interiors given

by HollowSpaces and TunnelFurniture

All feature types have thematic attributes (like class, function,

and usage)

Terrain Intersection Curves



Tunnel Model in UML [draft; simplified]

29. Februar, 2008

<<Feature>>_AbstractTunnel

<<Feature>>_BoundarySurface

<<Feature>>RoofSurface

<<Feature>>WallSurfacee

<<Feature>>ClosureSurface

<<Feature>>TunnelInstallation

<<Feature>>HollowSpace

<<Feature>>TunnelFurniture

<<Feature>>_Opening

<<Feature>>Window

<<Feature>>Door

<<Feature>>Tunnel

<<Feature>>TunnelPart

<<Feature>>core::_CityObject

<<Geometry>>gml::_Geometry

<<Object>>core::ImplicitGeometry

<<Feature>>GroundSurface

*

0..1

interiorFurniture

0..1

lod1-4Geometry

lod3-4Geometry

lod3-4Geometry

lod2-4Geometry

*

*

consistsOfTunnelPart

* 0..2opening

lod4Geometrylod2-4Geometry

*

*

boundedBy

*

*

boundedBy

*

*tunnelInstallation

*

*

interiorHollowSpace

Visual Paradigm for UML Standard Edition(Technical University Berlin)



Example for a Tunnel in LODs 1-4

LOD 1 LOD 2 LOD 3 LOD 4

Tunnel

Tunnel

interior(cut 1)

Tunnelinterior(cut 2)

Image source: Karl-Heinz Häfele, KIT



Modeling a Metro System using CityGML

Underground part of the metro station

(underground LOD3 Building object)

Connecting tunnel between two metro stations(Tunnel object, e.g.

in LOD3)

Above ground entry to the metro station(LOD3 Building)

Metro station + tunnel Digital Terrain Model (e.g.

in LOD1)

These two objects also could be

represented as oneBuilding with

two BuildingParts



Summary

Semantic 3D City Models (= Urban Information Models)allow for 3D visualizations AND thematic analyses facilitate comprehensive analyses on the urban scale in the fields of

e.g. energy assessment, environmental simulation, urban planning

CityGML intended to be used as a basis for standardized information structuring and data exchange

extension mechanisms like Generics & ADE provide flexibility

International adoption and system implementations are making steady progress

Increasing number of cities worldwide are using CityGML

Active further development within SIG 3D and OGCCityGML 1.1 to be released by end of 2011 / beginning of 2012



Research Topics with Relations to CityGML

3D city model validation 3D generalization 3D data integration Automatic extraction of semantic 3D city models

from sensor data or CAD/CG models Reconstruction of Building Information Models from CityGML

Dynamic models, relation to procedural models Urban data mining (DB) index structures for efficient visibility analyses 3D Cartographic Styling of 3D City Models

Label Placement, Symbolization

Current Status and Roadmap of CityGML

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