1. Presented by: Marco Soave
Fondazione Graphitech, Italy

2. CityGML as a standard
• CityGML is designed as an open data model and XML-based format for the
storage and exchange of virtual 3D city models.
• CityGML is an application schema of the Geography Markup Language 3
(GML3)
• CityGML is based on a number of standards from the ISO 191xx family, the
Open Geospatial Consortium, the W3C Consortium, the Web 3D
Consortium, and the Organisation for the Advancement of Structured
Information Standards (OASIS)
• 14th of March 2012: the members of the OGC have adopted version 2.0.0
of CityGML as an official OGC Standard.

3. CityGML
• CityGML defines the classes and relations for the most relevant topographic objects
in cities and regional models with respect to their
geometrical, topological, semantic, and appearance properties
• CityGML is applicable for large areas and small regions and can represent the terrain
and 3D objects in different levels of detail simultaneously ( 5 different LoD)
• CityGML can describe many geographical festures: taxonomies and aggregations of
Digital Terrain Models, sites (including buildings, bridges, tunnels), vegetation, water
bodies, transportation facilities, and city furniture

4. CityGML LoDs
• The informations stored the LoDs changes regarding the described object.
• e.g. : building LoDs
LoD Described features
0 FootPrint
1 Block model w/o roof
structures
2 Building model with texture
and roof model
3 Detailed architecture model
with external doors and
windows
4 Interior model including
rooms, stairs, windows, doors,
furnishings...

5. Smart Cities and CityGML

6. The i-Scope EU project
“i-SCOPE aim to deliver an open source toolkit for 3D
smart city services based on 3D Urban Information
Models (UIM), created from accurate urban-scale
geospatial information.”

7. The i-Scope scenarios:
1) Improved inclusion and personal
mobility of aging people and
diversely able citizens;
2) Energy dispersion & solar energy
potential assessment;
3) Noise mapping & simulation.

8. CityGML use in different scenarios
• A complete and reiable 3D city model is mandatory to process in a correct way
the input data and obtain good and precise results
• CityGml standard can be used to describe and visualize the results obtained in
the three scenarios.
• The standard allow the use of generic object, attribute and also to reference
external data
• The standard allow the use of differents and user defined ADE ( application
domain extensions ) for a spefic use case

9. Scenario 1: routing for aging people and diversely
able citizens
• CityGml is not the best format for routing calculation
• The TransportationComplex in LoD 0 can describe the road network, the
Sidewalks, Pedestrian crossing and Taxi ranks
• Extension of TransportationComplex can be used to describe
ramps, Elevators, Stairs and Barriers
• CityFurniture object can be used to describe Traffic lights for
pedestrians, public transport stations and Mobility obstacles
• Handicap entrances can be
treated as Building elements
• Also buildings interior routing
can be done in some ways

10. CityGML use in different scenarios
Scenario 2: Energy dispersion & solar energy potential assessment
• A reliable 3D city model is of fundamental importance for this task and the
calculation of the output
• The information obtained from the elaborations can be
• stored in a CityGML file using some specific generic attribute
• an ADE regarding the energy classification and characteristic of the buildings
can be deployed
• represented using appearance model related to the attribute
• represented as a big image that can be superimposed to the orthophotos

11. CityGML use in different scenarios
Scenario 3: Noise mapping & simulation
• Crown data acquisition in completely independent from CityGML
• The first ADE deployed for CityGML is the Noise ADE that has is composed
by a series of attributes that can be attached to Transportation features
e.g. roads, rail etc., Building features (at the _AbstractBuilding class) and
CityFurniture.
• As in the energy scenario the obtained results can be visuazlized using an
apparence model fitted to some specific parameters contained in the
noise ADE.

12. Management of CityGML data
• Many different software and suite exist, bot open source and not, for the
management of the CityGML data
• A complete list can be found here:
http://www.citygml.org/index.php?id=1538
• In the following a list of the sw used in the i-Scope project to manage the CityGML
data:
• M.o.s.s. is has developed the Novafactory platform able to:
• generate the CityGML data starting from digital terrain and surface
model ( DSM + DTM ) and buildings footprint
• manage and allow the final user to access, import and export new data
• a sketchUp plug-in allow the final user to edit the existing data or cerate
new one
• Technische Universität Berlin has developed a set of really useful tools:
• CityGML 3d spatial extension for both oracle and PostGis databases
called 3D City DB
• A complete and intuitive GUI to import and export
data from the database called Importer/Exporter Tool
• CityGML xml schema binding Java libraries called citygml4j

13. Visualization of CityGML data
• Many software exist to visualize directly CityGML data, but they are quite simple
and doesn't allow to integrate different data layer in the same visualization page
• Many problem exist when trying to visualize big datSet in a geoBrowser:
1. the number of polygons can be really high using the highest LoD
2. the size of the data to be transferred to the client can be huge
3. cityGml format is not aimed for visualization purpose
• Possible solutions are:
1. decrease the LoD as a function of the
distance from the camera
2. transmit only the needed data at each time
and store just received data in a local cache
3. use cityGml format to store the
information, but transmit to the client the
data to be visualized in a different format
like Kml ( adapt also to be visualized in
Google Hearth )

14. Visualization of CityGML data
Use KML for visualization purpose:
• KML is a widely used format as OGC standard and Google Heart default 3D
format
• Allow to split the data set in regions (tiles) that can be streamed and visualized
• Each building/region can be visualized for a pre-determinated range of visible
pixel obtaining a sort of intrinsic LoD structure
• The data can be visualized in the widely used Google Earth geobrowser
• 3D city DB Importer/Exporter allow to export cityGML data in KML format

15. Visualization of CityGML data
Methods to deliver the data to the client:
• WFS (OGC standard): web feature service
• W3DS (OGC draft): web 3 dimensional service
• WVS (OGC draft): web view service

16. Visualization of CityGML data
X3D format:
• the data can be served to the client in X3D format using one of the previous
described service
• X3D has many advantages:
• standardized format with Geospatial capabilities
• aimed at the 3d visualization
• allow events, scripting, sound, numerous sensors, programmable
shaders, and more…
• X3DOM is an adaption of the X3D standard to (X)HTML
• HTML5 can be used to provide a UI for accessing the W3DS and
portraying over X3DOM  every html5 compatible browser (also
mobile) can visualize the data

17. Visualization of CityGML data
Visualization of the CityGML format directly inside Nasa World Wind:

18. Thank you for your attention
Contact details
Marco Soave
Fondazione Graphitech
Via Alla Cascata, 56/C 38123
Trento ITALY
e-mail: marco.soave@graphitech.it
Web page: www.graphitech.it