Use of CityGML standard in the context of Smart City

i-SCOPE - interoperable Smart City services through an Open Platform for urban Ecosystems

Presented by: Marco SoaveFondazione Graphitech, Italy

interoperable Smart City services through an Open Platform for urban Ecosystems

Use of CityGML standard in the context of Smart Cities


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.


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


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...


Smart Cities and CityGML


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.”


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.


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


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



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



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.


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

http://www.citygml.org/index.php?id=1538


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 LoD2. the size of the data to be transferred to the client can be huge3. cityGml format is not aimed for visualization purpose

• Possible solutions are:1. decrease the LoD as a function of the

distance from the camera2. transmit only the needed data at each time

and store just received data in a local cache3. 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 )



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



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



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



CityGmlVisualizerVideo .mp4

Visualization of the CityGML format directly inside Nasa World Wind:


Thank you for your attention

Contact details

Marco SoaveFondazione Graphitech Via Alla Cascata, 56/C 38123 Trento ITALY e-mail: [email protected] Web page: www.graphitech.it

Technology

Use of CityGML standard in the context of Smart City