This document summarizes research on virtual city models (VCMs) from a global perspective. It identifies over 1,000 VCMs worldwide, covering over 83,000 km2 across 80 countries. While research on VCM production and usage has increased since the 1990s, most studies are limited to a single city or country. The document presents an updated global review of VCMs, mapping their locations and finding that Europe has the most (649) while over 1,000 cities have multiple VCMs. It concludes that VCM development is growing rapidly but challenges around online access remain, recommending a crowdsourced approach to maintain comprehensive global data.

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Virtual City Models - A Global Perspective - Short Paper
Peter James Morton, Northumbria University
Newcastle, UK
peter.j.morton@northumbria.ac.uk
www.virtualcitymodels.co.uk
Supervisors: Dr Emine Mine Thompson, Prof. Ruth Conroy Dalton
Research in the production, maintenance and usage of Virtual City Models (VCMs) has been
widely published from a range of disciplines since the early 1990’s. Although our understanding
of the processes and technologies associated with these models has improved significantly, a
number of issues still require attention. In particular it can be seen that the majority of current
research regarding the production, maintenance and usage of VCMs is restricted to the geographic
locality of the author, that being either city or country. There is a distinct lack of research which
takes into account the global perspective in the development and distribution of such models. The
paper presents the first steps in the collation and representation of a global perspective regarding
VCMs. It aims to provide researchers and professionals with a single source regarding the
development and distribution enabling a clearer understanding of VCMs on a global scale.
Introduction
Batty et al. (2000) carried out a worldwide review of VCMs and identified over 60 'serious
applications' of virtual city models. This paper represents an update of this previous
worldwide review and presents the development and distribution of VCMs on a global scale.
Research in the production, maintenance, usage and distribution of VCMs has been widely
published since the early 1990's from a range of disciplines including; geography, landscape
and environmental planning, urban planning, architecture, geo-information science and
computer graphics science.
Virtual Cities
The graphical representation of cities has been continuingly evolving over time; from two-
dimensional maps, 3D physical scale models and the digital representation in the form of
VCMs. VCMs in their purest form can be simply described as computer generated three-
dimensional (3D) geometric model with sufficient and consistent detail and accuracy as to
portray both terrain and urban structures of a city.
These digital representations of real life cities in recent years has become a topic of interest in
both research and professional communities primarily due to the advancements in the
technologies and practices used for data acquisition, reconstruction and maintenance of
VCMs. Recent innovations in computing, technology and sensor systems have provided a
new base line for the construction of VCMs. Advancements in computing power has enabled
the production and storage of more complex models with larger file sizes than ever before.

2. CityGML in National Mapping Workshop, Paris, 2013
VCMs have been created for a variety of different applications, either singular or
multifunctional. Batty et al. (2000); (Kolbe & Groger, 2003; Groger & Plumer, 2011) list
several different categories;
• Emergency Response/ Disaster Management
• Urban Planning, Architecture and Property Analysis
• Telecommunications, Infrastructure, Facilities and Urban Management
• Tourism, Entertainment, E-commerce and City Portals
• Environment and Traffic Simulation
• Education and Learning
A Global Perspective
The number of VCMs being created by municipalities, local and national councils, surveying
agencies, educational institutions and other organisations is steadily increasing, primarily due
to the significant advancements in 3D reconstruction methods (Ross, 2012). These
technological advancements include developments in data acquisition techniques such as
photogrammetry, LiDAR and the incorporation of point cloud data from 3D laser scanning
among others.
Morton et al. (2012) identified over one thousand VCMs worldwide (Table 1 and Figure 1).
The data collected from the above searches has detailed VCM coverage at over 83,000km2
,
spread over 80 countries and all continents. Further investigation also found 286 cities having
more than one VCM created. Although the size, LOD, data age and accuracy attributes etc
does vary. Additional VCM details can be found at http://www.virtualcitymodels.co.uk.
Continent Total VCMs
Europe 649
North America 279
Asia 143
South America 52
Africa 33
Australia and Oceania 32
Total 1188
Table 1: Virtual City Models by Continent
Please note historic VCMs, identified as those created from historical archive data, were not
included in this review, primarily to the difficulty in identification due to limited online
presence. However, it is believed once the Virtual City Models website becomes more active
and gains a larger online presence, more information on historic VCMs will be gathered. The
Virtual City Models website acts as a central hub for VCM research and data.

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Figure 1: Global Distribution of Virtual City Models
Presenting the Global Perspective
As identified previously, it is very difficult to present a global perspective and the geographic
distribution of VCMs in their entirety, especially in textual form. To cater for this, the VCM
geographic locations were geo-located on an interactive map, hosted on the authors’ research
website (http://www.virtualcitymodels.co.uk). This map aims to provide users with an
unbiased, single point of contact for information regarding VCMs.
Conclusion
This paper presented the first steps in the collation and representation of a global perspective
regarding VCMs. It utilised visual and textual techniques to present the worldwide
distribution and locations of VCMs. The paper shows there are vast numbers of these models
available globally, over one thousand to date, with many cities having multiple models
produced from different sources embodying varying data currency. The collation and
production of a global perspective clearly illustrates the geographic locations of VCMs and
those countries, which are leading the way in their production.
Based on the worldwide review carried out it is very clear the field of VCMs is still moving
very rapidly and the production of VCMs is steadily growing. However there is still which
are still affecting the development of VCMs, their online presence is a particular problem
with web links within research papers no longer available. To enable a complete global
perspective regarding the development and distribution of VCMs it is recommended a crowd
source concept be adopted to enable consistent up to date data regarding new VCMs.

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References
Batty, M., Chapman, D., Evans, S., Haklay, M., Kueppers, S., Shiode, N., Smith, A. &
Torrens, P. M. (2000) 'Visualizing the City: Communicating Urban Design to
Planners and Decision-Makers', Centre for Advanced Spatial Analysis: Working
Paper Series, Paper 26 (15), pp. 405-433.
Groger, G. & Plumer, L. (2011) 'How to achieve consistency for 3D city models',
Geoinformatica, 15 (1), pp. 137-165.
Kolbe, T. H. & Groger, G. (2003) 'Towards unified 3D city models', ISPRS Comm. IV Joint
Workshop on Challenges in Geospatial Analysis, Integration and Visualisation II.
Stuttgart.
Morton, P. J., Horne, M., Dalton, R. C. & Thompson, E. M. (2012) 'Virtual City Models:
Avoidance of Obsolescence', eCAADe 30th conference: Digital Physicality | Physical
Digitality. 12-14 September. Prague, Czech Republic, pp. 213-224.
Ross, L. (2012) 'City GML - Interoperable semantic 3D city models', ISPRS Journal of
Photogrammetry and Remote Sensing, 71, pp. 12-33.