Friday, December 14, 2012

Fusing remote sensing with demographic data for synthetic population generation

When building agent-based models related to "real" world locations and people, the challenge is to build agents which resemble people on the ground. I have blogged about microsimulation approaches before and their utility with respect to agent-based models. A new paper in the International Journal of Geographical Information Science by alumnae from the Department of Computational Social Science here at GMU have developed a new algorithm which could prove useful. Below is abstract of the paper:
We develop a new algorithm for population synthesis that fuses remote-sensing data with partial and sparse demographic surveys. The algorithm addresses non-binding constraints and complex sampling designs by translating population synthesis into a computationally efficient procedure for constrained network growth. As a case, we synthesize the rural population of Afghanistan, validate the algorithm with in-sample and out-of-sample tests, examine the variability of algorithm outputs over k-nearest neighbor manifolds, and show the responsiveness of our algorithm to additional data as a constraint on marginal population counts.

Full Reference:

Rizi, S.M.M., Łatek, M.M. and Geller, A. (2012), 'Fusing Remote Sensing with Sparse Demographic Data for Synthetic Population Generation: An Algorithm and Application to Rural Afghanistan', International Journal of Geographical Information Science, DOI:10.1080/13658816.2012.734825.

Thursday, November 29, 2012

Call for Papers: 9th European Social Simulation Association Conference

9th European Social Simulation Association Conference
Warsaw School of Economics, Warsaw, Poland
September 16-20, 2013

The European Social Simulation Association and Warsaw School of Economics, Division of Decision Analysis and Support, invite researchers and scholars interested in applications and theoretical foundations of simulation modeling in social sciences to participate in the 9th European Social Simulation Association Conference.

The conference aims to provide an interdisciplinary forum for social scientists, theorists, applied researchers and simulation modelers to cooperate and exchange ideas concerning state of the art in methods and applications of computational social sciences.

Scope and Interests

The topics of interest include, but are not limited to:
  • Applications of agent-based modeling in social sciences
    • Agent-based computational economics & finance
    • Conflict resolution & cooperation
    • Coupled human-natural systems
    • Diffusion of innovations
    • Dynamics of trust, social norm, structures, reputation & opinion
    • Epidemiology & pharmacoeconomics
    • Group decisions & collective behaviors
    • Market design, mechanism design & auctions
    • Privacy, safety & security
    • Public policy & regulatory issues
    • Resource management, environmental practices & policy
    • Social emergence & evolution of institutions
    • Social media and volunteered information
    • Social networks and their dynamics
  • Tools and methods for development of simulation models 
    • Advanced distributed computing
    • Agent ontologies
    • Agent-embodied Artificial Intelligence
    • Model replication, verification & validation
    • Participatory & Human-in-the-Loop simulations
    • Simulation software & programming computational frameworks
  • Techniques for visualizing, interpreting and analyzing simulation outputs
    • Coupling simulations and optimization methods
    • Data analysis software for simulations
    • Experiment design and data farming for simulations
    • Simulation metamodels
    • Statistical & data mining techniques for simulated data
  • Full paper - in the length of 10 to 12 pages, which should be comprehensive and consists of detailed presentation of theory, methodology and simulation results
  • Extended abstract - in the length of 3 to 4 pages, which presents the current topic in progress with enough detail to ensure proper evaluation
  • Poster - should present the current work in progress
 Contributions can be submitted to general session or the following special tracks:
  • Adaptive behavior , social interactions and global environmental change: an agent-based perspective (chairs: T. Filatova, G. Polhill, R. van Duinen)
  • Applications of computational social science in conflict and sensitive contexts (chair: A. Geller)
  • Business applications of computational social science (chair: M. Łatek)
  • Heterogeneity and interaction in macroeconomic modeling (chair: G. Koloch)
  • Social simulation of science processes (chair: F. Squazzoni)
  • Statistical analysis of simulation models (chair: B. Kamiński)
  • Using qualitative rules to inform behavioral rules (chair: B. Edmonds)
Important dates
  • Registration opens: 1 January 2013
  • Paper submission closes: 1 March 2013
  • Notification of acceptance: 15 April 2013
  • Final manuscript due: 15 May 2013
Paper publication
  • Accepted full papers will be published by Springer in the conference proceedings series "Advances in Intelligent Systems and Computing", (indexed by ISI Proceedings, DBLP, Ulrich's, EI-Compendex, SCOPUS, Zentralblatt Math, MetaPress, Springerlink).
  • Authors of selected full papers or extended abstracts will be invited to submit their extended version for special issue of Central European Journal of Economic Modelling and Econometrics, (indexed by IndexCopernicus, IC Value in 2011: 4.85 and RePEc).
  • Full paper abstracts, extended abstracts and poster summaries will be presented on conference website.
Local organizing committee contact:
Conference website:

Wednesday, October 31, 2012

Book Reivew: Modeling and Simulating Urban Processes

Recently I reviewed a book for JASSS entitled "Modeling and Simulating Urban Processes" edited by Andreas Koch and Peter Mandl. The full review can be found here.

Modelling and Simulating Urban Processes brings together six papers ranging from spatial-econometric models to geostatistical techniques and multi-agent systems, to analyse and visualise patterns of social organisation, individual behaviour and spatial fabrics to explore urban change. As the preface to the edited volume states: "Modelling and (geo-)simulation techniques offer a wide range of opportunities which cannot completely or adequately be accomplished by traditional quantitative or qualitative methods". The remainder of the book follows up on this discussion in more details.

Overall, the book is well written and referenced which allows the reader to delve deeper into any of the topics discussed. As the papers are longer than those of typical journal articles, it allows the authors to describe the literature and the models in more detail than is normally possible and presents a good survey into the state of the art for modelling and simulating a variety of urban processes.

New Paper: Agent-based modeling of Slums

We have just had a  paper published in Journal of Artificial Societies and Social Simulation the entitled "Slumulation: An Agent-Based Modeling Approach to Slum Formations". This paper adds to the small but growing body of agent-based models exploring slums. Below is the abstract from the paper:
Slums provide shelter for nearly one third of the world's urban population, most of them in the developing world. Slumulation represents an agent-based model which explores questions such as i) how slums come into existence, expand or disappear ii) where and when they emerge in a city and iii) which processes may improve housing conditions for urban poor. The model has three types of agents that influence emergence or sustenance of slums in a city: households, developers and politicians, each of them playing distinct roles. We model a multi-scale spatial environment in a stylized form that has housing units at the micro-scale and electoral wards consisting of multiple housing units at the macro-scale. Slums emerge as a result of human-environment interaction processes and inter-scale feedbacks within our model.

This paper is a starting point for a recently awarded a National Science Foundation grant entitled "An Integrated Simulation Framework to Explore Spatio-Temporal Dynamics of Slum Formation".  Moreover, anyone wanting to run or download the model can do so here.

Full reference:
Patel, A., Crooks, A.T. and Koizumi, N. (2012), Slumulation: an Agent-based Modeling Approach to Slum Formations, Journal of Artificial Societies and Social Simulation, 15 (4). Available at

Tuesday, October 23, 2012

GeoMason Cookbook

While GeoMason is still undergoing development. Mark Coletti has put together a Cookbook for 'recipes' for using GeoMason. The Cookbook is available from  here.

It gives examples of how to read and write geospatial data along with using geospatial data within your agent-based model (e.g. having an agent follow a gradient) and much more. Each example is associated with a GeoMason model example.

Mark welcomes any comments so please send them. For example, what GIS functions  do you want more information on? What are the common problems you have encountered using GeoMason?

Thursday, October 18, 2012

Research Update

With the semester now well underway, I have been reflecting on some of the recent work we have been doing at George Mason University. This is currently taking two strands, the first being agent-based modeling and the second being deriving information from social media. Hopefully by the end of the semester, these two strands will be merged together.

One of the models we are working on is the movement of people across national boarders. Below is a visualization of our work looking at the movement of people across the US/Mexico border which a specific focus on Arizona.

Moreover, we have continued to work diseases and refugee camps. We are scaling up the model to represent the entire population of the Dadaab refugee camps along with verifying the model and exploring the spatial characteristics of the model (i.e the spread of cholera). If anyone will be at the annual North American Meetings of the Regional Science Association International in Ottowa  Canada feel free to come and listen to our presentation. The movie directly below shows the spread of cholera in one camp, while the second movie shows how cholera can be spread throughout the camps by people becoming infected and moving between the different camps.

Some of this work has been feated in UPMagazine and Trajectory Magazine:

Metcalfe, M. (2012), The Bounds of Rationality, UP Magazine, May, Issue 5: 40-43.
Quinn, K. (2012), Visualizing the Invisible:GMU Pioneers a New Approach to Harvesting GEOINT, Trajectory Magazine, Fall, 11-12.

Wednesday, October 17, 2012

Model Replication via OpenABM

The OpenABM website is a great resource for agent-based modelers, I often suggest to my students to visit the site to see the range of possibilities to which agent-based models can be used for.

Recently it was announced that the winner of CoMSES Net Model Recovery and Replication Drive was Torsten Hagerstrand's 1965 Spatial Innovation Diffusion Model. To quote from the announcement it is the "Earliest known calibrated and validated simulation with implicit "agent based" methodology." Sean Bergin replicated the model and provides a great ODD documentation of the model. More  details can be found here.

The OpenABM site has many models which one can view, download and experiment with, including a replication of the Artificial Anasazi model of Axtell et al., (2002) by  Marco Janssen.

Monday, October 15, 2012

USGIF 2012 Achievement Award for Academic Research

The United States Geospatial Intelligence Foundation (USGIF), has just awarded our team the 2012 USGIF Achievement Award for Academic Research for our pioneering work on harvesting geospatial intelligence from social media. This pioneering work has led to the new computational paradigm of GeoSocial Analysis, providing a new understanding of sociocultural dynamics in space and the links among various locations. Below is the movie from the awards ceremony at the GEOINT 2012 Symposium.

Also our work has recently been been featured in the the USGIF Trajectory Magazine.  The first article entitled "OSINT Goes Social: Social media presents new opportunities and challenges for deriving open source intelligence" by Jim Hodges, discusses the potential of social media for open source intelligence.

In the second article entitled "Visualizing the Invisible" by Kristin Quinn discuses how our pioneering work is leading to a new approach to harvesting GEOINT.

Call for Papers: Agent-Based Models of Geographical Systems

Call for Papers: Agent-Based Models of Geographical Systems
IGU Leeds, Applied GIS and Spatial Modelling: 29 May – 2 June 2013

The use of agent-based models is now becoming widespread within the social sciences. With the maturity of these methodologies, there has been an accompanying development in applications for exploring a wide range of geographical, and more broadly, social sciences problems facing society.

The aim of this session is to bring together researchers who are using ABM within the context of Applied GIS or Spatial Modelling.  Papers which explore the relationships between ABM and other related techniques such as spatial microsimulation or cellular automata, and their uses within policy frameworks of substantive applications to geographical problems, will be particularly welcome.
Specific areas of interest include the following:
  • Linking ABM to GIScience and visualization of models and their outputs
  • Work concerned with the calibration, verification and validation of models, or the development of appropriate methods such as genetic algorithms and other geocomputational methods
  • The use of models alongside new forms of data such as social media or volunteered geographical information
  • Representations of agent behavior within geographical systems
  • Substantive applications to geographical problems and policy issues
  • Papers which explore the interactions and linkages to other methods and techniques

Important Dates:
  • Abstract submission: 250 – 300 words before Dec 01 2012
  • Notification: before Feb 01 2013
  • Conference dates: May 29th – 2nd June 2013, Leeds, UK.


Sunday, September 09, 2012

Call for papers: Agent-Based & Cellular Automata Models for Geographical Systems @ AAG 2013


SPECIAL SESSION(S): Agent-Based & Cellular Automata Models for Geographical Systems

Association of American Geographers Annual Meeting
April, 9-13th, 2013, Los Angeles, USA

The use of Agent-based Modeling (ABM) and Cellular Automata (CA) models within geographical systems are starting to mature as methodologies to explore a wide range of geographical and more broadly social sciences problems facing society. The aim of this session(s) is to bring together researchers utilizing agent-based models, CA (and associated methodologies) to discuss topics relating to: theory, technical issues and applications domains of ABM and CA within geographical systems.

We would particularly welcome papers relating to:
  • Validation, verification and calibration of Agent-based and CA models
  • Hybrid modeling approaches (e.g. utilizing Spatial Interaction, Microsimulation, etc.)
  • Handling scale and space issues
  • Visualization of agent-based models (along with their outputs)
  • Ways of representing behavior within models of geographical systems
  • Participatory modeling and simulation
  • Applications: Ranging from the micro to macro scale
Please e-mail the abstract and key words with your expression of intent to Andrew Crooks <; by October 15th, 2012. Please make sure that your abstract conforms to the AAG guidelines in relation to title, word limit and key words and as specified at . An abstract should be no more than 250 words that describes the presentation's purpose, methods, and conclusions as well as to include keywords. Full submissions will be given priority over submissions with just a paper title.

Christopher Bone, Department of Geography, University of Oregon.
Andrew Crooks, Krasnow Institute for Advanced Study, George Mason University, USA.
Suzana Dragicevic, Department of Geography, Simon Fraser University.
Alison Heppenstall, School of Geography, University of Leeds, Leeds, UK .
Michael Batty, Centre for Advanced Spatial Analysis (CASA), University College London, London, UK.
Amit Patel, School of Public Policy, George Mason University, USA.

  • October 15th, 2012: Abstract submission and expression of intent to session organizers. E-mail Andrew Crooks by this date if you are interested in being in this session. Please submit an abstract and key words with your expression of intent. Full submissions will be given priority over submissions with just a paper title.
  • October 18th, 2012: Session finalization. Session organizers determine session order and content and notify authors.
  • October 20th, 2012: Final abstract submission to AAG, via All participants must register individually via this site. Upon registration you will be given a participant number (PIN). Send the PIN and a copy of your final abstract to Andrew Crooks . Neither the organizers nor the AAG will edit the abstracts.
  • October 24th, 2012: AAG registration deadline. Sessions submitted to AAG for approval.
  • April, 9-13th, 2013: AAG meeting, Los Angeles, USA

Tuesday, September 04, 2012

New paper: Agent-based modeling for community resource management: Acequia-based agriculture

We have just got a paper accepted in Computers, Environment and Urban Systems entitled "Agent-based modeling for community resource management: Acequia-based agriculture." In the paper we explore the complex social interactions of water management, which involves landowners collectively maintaining and managing ditches which distribute water among the properties.

This system of the physical ditches and the maintaining organization together is known as an acequia, and the landowners who maintain it are called Parciantes. Acequias are interesting to researchers because of the developed common property regimes they require to function. The water carried by the ditches is a shared resource, and the complex management system of the acequia has evolved to avoid Hardin’s tragedy of the commons with regard to natural resources in the sense that it prevents the resource from being overused or under-maintained to the detriment of everyone. Ostrom has extensively studied the process of sharing such resources, investigating the structures set in place to preserve them. In ‘‘Governing the Commons’’, her book on common pool resources and human–ecosystem interactions, she suggests a set of characteristics that define stable communal social mechanisms. These characteristics include the presence of environment-appropriate rules governing the use of collective goods and the efficacy of individuals in the system.

Below is the abstract from the paper:
Water management is a major concern across the world. From northern China to the Middle East to Africa to the United States, growing populations can stress local water resources as they demand more water for both direct consumption and agriculture. Irrigation based agriculture draws especially heavily on these resources and usually cannot survive without them; however, irrigation systems must be maintained, a task individual agriculturalists cannot bear alone. We have constructed an agent-based model to investigate the significant interaction and cumulative impact of the physical water system, local social and institutional structures which regulate water use, and the real estate market on the sustainability of traditional farming as a lifestyle in the northern New Mexico area. The regional term for the coupled social organization and physical system of irrigation is ‘‘acequias’’. The results of the model show that depending on the future patterns of weather and government regulations, acequia-based farming may continue at near current rates, shrink significantly but continue to exist, or disappear altogether.
In the figure below we show some of our efforts in verification of the model, specifically, the water network, after 100 years of regular maintenance (A) and after 100 years of no maintenance (B). The darker the line, the more clear the segment is of sedimentation; only unmaintained acequias are impacted by sedimentation in this model, and appear in lighter shades.

Below is a movie are a few sample model runs showing how different scenarios play out, specifically with respect to land-use change.

Full reference:
Wise, S. and Crooks, A.T. (2012), Agent Based Modelling and GIS for Community Resource Management: Acequia-based Agriculture, Computers, Environment and Urban Systems, 36(6): 562-572. (pdf)

Wednesday, August 22, 2012

Computational Social Science

In a post entitled "A New Kind of Social Science For The 21st Century" from, Nicholas Christakis talks about how Computational Social Science is going to change the social sciences in the 21st century. To quote from the article:
"In the 20th century, there was a tremendous expectation, or appreciation, for the role that the biological and the physical sciences could play in improving human welfare and human affairs. We had everything from the discovery of nuclear power to plastics to, in biology, the discovery of new drugs, beginning with penicillin (which is one of the gigantic feats of human ingenuity ever). We had this phenomenal progress that was made in the sciences, in the physical and the biological sciences.
In the 21st century, the social sciences offer equal promise for improving human welfare. The advances that we have made and will be making, especially in understanding human behavior and its very deep origins, will be translated into interventions of diverse sorts that will have a much bigger impact in terms of improving human welfare than many of the prior examples that I gave." 

If you have time, its well worth checking out the whole article or listening to the audio file.

Thanks to Jim Olds for the heads up.

Traffic Movement in London from Travel Cards

Why and how do people move around cities? Is it to get to work or to meet people? These are some questions one can explore if one has data. One can also explore what happens if a key transit stations or links is closed and how will this impact on the rest of the city.

Researchers from UCL have analyzed millions of Oyster Card journeys in a bid to understand how, why and where we travel in London. They used Transport for London’s database of 11 million records taken over one week from the Oyster Card electronic ticketing system.

Professor Michael Batty (UCL Centre for Advanced Spatial Analysis) and Dr Soong Kang (UCL Management Science and Innovation) applied the techniques of statistical physics to their mountain of raw data.

Such data could also be very useful if one was trying to build some spatial interaction models or hybrid agent-based models of residential location and employment or pedestrian models.

Thanks to Digital Urban and Mike Batty for pointing this work out to me.

Monday, August 20, 2012

Retail spatial interaction models

If you are interested in the applications of mathematical models especially those of spatial interaction models the movie below from a Open University Course called Modelling by Mathematics might be of interest. It discusses how to compute the impacts of new shopping centres on their surroundings in 1977.

Readers of this post might also be interested in Mike Batty's  book "Urban Modelling: Algorithms, Calibrations, Predictions" which was published in 1976 and is now freely available. Click here to download it.

The book covers a plethora of topics, introducing the reader to simulation models and the need for such methods. For example, "simulation methods are used to derive the behaviour of the system when the system is too complex to be modelled using the more direct analytic approach (Batty, 1976)."

The book provides a summary of the first generation of urban models referring to the key authors and models such as Lowry (1964) model and it successor including the Pittsburgh Time-Oriented Metropolitan Model (TOMM), the Projective Land Use Model (PLUM) for the San Francisco area, and a wide variety of Activity Allocation and Stocks-Activities models. The book presents how such models were mainly developed for practical planning situations through metropolitan planning agencies or consultants in North America and in several European cities. How at first, these models where developed with the aim of solving land-use and transportation questions, later being employed to address a wider range of urban problems.

Anyone interested in urban modelling and spatial interaction models is recommended to explore this book and check out Mikes Blog:

Lowry, I.S. (1964), A Model of Metropolis, Rand Corporation, Santa Monica, CA.

Monday, July 02, 2012

Complexity and Planning: Systems, Assemblages and Simulations

To quote from the book description:
Complexity, complex systems and complexity theories are becoming increasingly important within a variety disciplines. While these issues are less well known within the discipline of spatial planning, there has been a recent growing awareness and interest. As planners grapple with how to consider the vagaries of the real world when putting together proposals for future development, they question how complexity, complex systems and complexity theories might prove useful with regard to spatial planning and the physical environment. This book provides a readable overview, presenting and relating a range of understandings and characteristics of complexity and complex systems as they are relevant to planning. It recognizes multiple, relational approaches of dynamic complexity which enhance understandings of, and facilitate working with, contingencies of place, time and the various participants' behaviors. In doing so, it should contribute to a better understanding of processes with regard to our physical and social worlds.
We have a chapter in the book:

Crooks, A. T. (2012), The Use of Agent-Based Modelling for Studying the Social and Physical Environment of Cities, in De Roo, G, Hiller, J. and Van Wezemael, J. (eds.), Complexity and Planning: Systems, Assemblages and Simulations, Ashgate, Burlington, VT, pp. 385-408. (pdf)

The agent-based modeling (ABM) paradigm provides a mechanism for understanding the effects of interactions of individuals and through such interactions emergent structures develop, both in the social and physical environment of cities. This chapter explores how through the use of ABM, and its linkage with complexity theory, allows one to create agent-based models for the studying cities from the bottom-up. Specifically the chapter focuses on segregation and land-use change. Furthermore, it will highlight the growing interest between geographical information systems (GIS) and ABM. This linkage is allowing modellers to create spatially explicit agent-based models, thus relating agents to actual geographical places. This approach allows one to explore the link between socio-economic geography of the city and its built physical form, and can support decision-making regarding interventions within the social and physical environment. 

Our chapter can be downloaded from here.

Tuesday, June 26, 2012

Procedural Modeling of Cities: NetLogo

Thanks to the Electric archaeology blog, I have just been introduced to the Procedural Modeling of Cities pages from the Center for Connected Learning (CCL) and Computer-Based Modeling. The site has a number of simple to complex examples of city growth which might be of interest to those teaching basic concepts of urban systems via a modeling paradigm. I know they will come in handy with the courses I teach @ GMU.

Examples include the concepts relating to positive feedback, path dependence, sprawl which are part of the NetLogo Urban Suite .

Thursday, May 31, 2012

Diseases and Refugee camps

Dadaab refugee camp
One of the projects we are working on at GMU is exploring the the dynamics of refugee camps and the spread of diseases within such camps. 

Our initial focus is on the the Dadaab refugee camps which are located in Kenya, approximately 100 kilometers from the Somali border. The camps themselves are homes to roughly 500,000 people, with nearly 99% of the population coming from Somalia. Within the camps the mortality rate is ~ 0.44/10,000 per day with  diseases such as cholera and measles being among the causes of death.

Below are some movies of the prototype models that are currently being developed in Mason ABM toolkit and utilizing its GeoMason extension. The first movie shows a overview of the model dashboard, while the second show the spread of cholera within the area.

While the second movies (below) shows our first attempt at modeling one type of disease, that of cholera. In the simulation we pollute one bore hole with cholera and simulated how it might spread through the camp under specific conditions.

While this is still work in progress, we thought it worth sharing to see what feedback we may get. More details about the models will come soon.

Click here to see previous blog posts on diseases

Synthetic population data for the U.S

When creating agent-based models, one question is how many agents to include and where are they located.  Often we create synthetic individuals or households based on census data however, this can be a rather time consuming task. So a recent project from RTI has caught my attention. It is a  U.S. wide geospatially explicit synthetic population funded under a grant from NIH/NIGMS

The dataset provides a synthetic version of each household and person in the U.S. based on 2005-2009 ACS public use microdata and other sources.  LandScan 90-meter night-time population distributions were used to place each household across the landscape (a total of 112,383,675).

The basic website location for information and to download the data is at: 

Another short write up can be found here:

Call for papers: Intelligent Agents in Urban Simulations and Smart Cities

Readers of the blog might be interested in the "Intelligent Agents in Urban Simulations and Smart Cities" workshop at the  ECAI-2012 Conference in Montpellier, France, August 27 or 28, 2012.

To quote from the call for papers:
In this workshop, we intend to address specific methodological and technological issues raised by the deployment of agents in rich environments such as virtual cities. We will welcome contributions tackling issues related to reactive agents, cognitive architectures, the capacity to scale up to handle thousands or hundreds of thousands of agents, the ability to simulate realistic group behaviors which might be judged non rational, etc., all in the context of urban agents. We will also welcome contributions showcasing original applications of agent and multi-agent technologies within urban simulations, be it for design, planning, education, training, or entertainment. 

Workshop Chairs: 
  • Vincent Corruble (contact), Université Pierre et Marie Curie (Paris 6), France 
  • Fabio Carrera, Worcester Polytechnic Institute (WPI), USA 
  • Stephen Guerin, Santa Fe Complex, USA 

Important Dates: 
  • *6 June 2012*: Workshop paper submission deadline 
  • 28 June 2012: Notifications to authors (subject to modification) 
  • 13 July 2012: Submissions of camera-ready copies of selected papers 
  • 27 or 28 August 2012: Workshop date 

Submission information: 

Friday, May 18, 2012

A Semester with OpenSim

Over the last few months I have been teaching a class in the Department of Computational Social Science entitled "Building Virtual Worlds" where we surveyed the role of virtual worlds for social science research. The emphasis of the class was on tools, software frameworks, and applications of virtual worlds.  On the applications side we discussed how virtual worlds are being used for History, Archeology, Healthcare, Tourism, Urban Modeling, Architecture, Agent-based Modeling along with more generally teaching and learning. We explored a variety of tools for building virtual worlds before focusing on OpenSim. The movie below shows some of the final outputs using OpenSim.

We used OpenSim 0.7.3, configured with the Standalone-Hypergrid mode and a SQLite database hosted on a Windows 7 server. The server simultaneously simulated 64 different regions, and at various points during the semester the server hosted well over 15000 primitives (prims) and ran hundreds of scripts across this landscape; one region alone hosted over 8000 prims. 

Why so many regions? We were interested in how many the server could cope with but also we wanted to have a virtual world representing the whole of the GMU Fairfax campus  (~4km2) and regions in OpenSim are limited to 256m by 256m. We built the terrain for the campus utilizing the National Elevation Dataset (NED) DEM from the United States Geological Survey which was first manipulated in ArcGIS before being processed in  L3DT (Large 3D Terrain Generator). Finally, the DEM was imported into OpenSim. The movie below should give a sense of what the basic terrain looks like.

Once the terrain was built, we populated it with buildings, however, we were not just interested in the external appearance of the buildings but also there internal structure for modeling and simulation purposes.  Therefore the class focused their attention on building a highly detailed Johnson Center.

Model of Johnson Center taken from Google SketchUp 3D Warehouse

Vector based, 2D CAD files were obtained and imported into Google SketchUp before using SketchLife to build the 3D initial building core, walls, doors and windows.

Constructing a vector-based model of the Johnson Center internal structure
The SketchLife final rendering of the Johnson Center

Once built in SketchUp using SketchLife the model was imported into OpenSim 

External view “in world” of what we accomplished in building the Johnson Center
In addition to using SketchLife for the JC, many objects such as chairs, staircases and tables were either built using the tool or those native to OpenSim.

An “in world” shot at ground level, on the 1st floor, viewing the atrium and clock tower
 in the Johnson Center
CSS class photo "in-world"

However, our work with OpenSim does not stop here, below is another movie of some ongoing work with one of our PhD students, Chris Rouly who is creating agent-based models embedded in OpenSim to explore past habitats among many other things.

I would like to thank the "Building Virtual Worlds" class and the Department for enabling this blog post.

Wednesday, April 25, 2012

SimTable and fires

To quote from the site "The SimTable takes sandtable exercise to the next level by making sandtables real. The SimTable is a 3D interactive fire simulator, bringing sandtable exercises to life." Below is a Los Alamos National Lab video demonstrating their use of the SimTable in their Emergency Operations Center.

The movie below demonstrates more of the functionality of SimTable , specifically how one can simulate rainfall and how it flows over the terrain. Or how it can be used to simulate a wildfire spreading and how residents might evacuate from the area. 

Monday, April 16, 2012

Natural Disasters and Crowdsourcing: Haiti

Natural disasters such as earthquakes and tsunamis occur all over the world, altering the physical landscape and often severely disrupting people’s daily lives. Recently researchers’ attention has focused on using crowds of volunteers to help map the infrastructure and devastation caused by natural disasters, such as those in Haiti and Pakistan. For example, in the movie below shows the response to the earthquake by the OpenStreetMap community within 12 hours of the earthquake. The white flashes indicate edits to the map (often by tracing satellite/aerial photography).

While this data is extremely useful, as it is allows us to assess damage and thus aid the distribution of relief, but it tells us little about how the people in such areas will react to the devastation, the supply of food, or the reconstruction. To address this, we are exploring how agent-based modeling can be used to explore peoples reactions. To do this we have created a prototype spatially explicit agent-based model, created using crowdsourced geographic information and other sources of publicly available data, which can be used to study the aftermath of a catastrophic event. The specific case modeled here is the Haiti earthquake of January 2010. Crowdsourced data is used to build the initial populations of people affected by the event, to construct their environment, and to set their needs based on the damage to buildings. 

The idea behind the model is to explore how people react to the distribution of aid, as well as how rumors propagating through the population and crowding around aid distribution points might lead to food riots and similar social phenomena. Such a model could potentially provide a link between socio-cultural information of the people affected and relevant humanitarian relief organizations.

The animation above shows one simulation run where there is the spread of  information and agent movement (red dots) around one center (blue dot). While the chart below shows how over time the density of agents around the food station increases over time.

The idea behind such a model is one can take crowdsourced information and fuse it into an agent-based model and see how people will react to the distribution of food centers. For example, the movie below shows how agents find out about four (hypothetical) different food centers and decide whether or not to go to them in a 6 by 8km area of Port-au-Prince.

Spread of information and agent movement (red dots) in a 6 by 8km area of Port-au-Prince.

More details about this model to come......

Friday, April 13, 2012

#Earthquake: Twitter as a Distributed Sensor System

Our work on using social media continues to develop and we have recently had a paper accepted in Transactions in GIS, entitled "#Earthquake: Twitter as a Distributed Sensor System". Below we present our abstract and some of the results.
Social media feeds are rapidly emerging as a novel avenue for the contribution and dissemination of information that is often geographic. Their content often includes references to events occurring at, or affecting specific locations. Within this paper we analyze the spatial and temporal characteristics of the twitter feed activity responding to a 5.8 magnitude earthquake which occurred on the East Coast of the United States (US) on August 23, 2011. We argue that these feeds represent a hybrid form of a sensor system that allows for the identification and localization of the impact area of the event. By contrasting this to comparable content collected through the dedicated crowdsourcing ‘Did You Feel It?’ (DYFI) website of the US Geological Survey we assess the potential of the use of harvested social media content for event monitoring. The experiments support the notion that people act as sensors to give us comparable results in a timely manner, and can complement other sources of data to enhance our situational awareness and improve our understanding and response to such events.
The movie below show geolocated tweets with references to the earthquake through keyword (earthquake or earth and quake) and hashtag search (#earthquake or #quake) for the first hour after the earthquake.

The following images give a glimpse at some of our analysis.
Response pattern as function of distance from epicenter for the first 400 seconds after the earthquake. At the top we see a plot of (reaction time, distance) of all tweets during that period. At the bottom we show the histogram of the number of tweets as a function of distance.
Locations of the 40 tweets in the shaded area of the figure above overlaid over the USGS CDI scale map. Tweet locations are marked as green circles. Color-coding in the graph is ranging from red (high perceived intensity) to yellow (lower perceived intensity). The dashed line shows a distance of approximately 950 km (8.5 degrees of angular distance) from the epicenter.
The movie below gives you an idea of some of the tweet content:

Full reference to this paper is:
Crooks, A.T., Croitoru, A., Stefanidis, A. and Radzikowski, J. (2013), #Earthquake: Twitter as a Distributed Sensor System, Transactions in GIS, 17(1): 124-147. (pdf)

Wednesday, March 14, 2012

Distributed MASON

Last week, the Center for Social Complexity at GMU, hosted Prof. Vittorio Scarano and Carmine Spagnuolo from the ISISLab of the Università degli Studi di Salerno who have been working on a distributed version of MASON (DMason). The idea is that one can create an agent-based model in MASON and then use the framework to easily distribute it over many machines. The movie below shows an example of what can be done. More information can be found here.

However, if you don't use MASON, you might also be interested in Repast for High Performance Computing

Sunday, February 19, 2012


A project we have been working on at GMU called ElectionGauge has now gone live (although still under development). The idea about the project is tie geo-spatial analysis, linguistic analysis, and social network analysis to analyze Twitter responses to the upcoming US elections in real time with the aim of predicting election results.

One question we are exploring is  do the tweets of users match the speech of candidates? For example, as Maksim Tsvetovat, one of the co-founders says “repeal Obamacare” might identify you as Tea Partier, while “legalize marijuana” puts you in Ron Paul’s camp. While still in beta, below is snapshot from the site:

Find out more see: @maksim2042, @JackieKazil & @ElectionGauge or at Tech Cocktail

Friday, January 27, 2012

Social Media and the Emergence of Open-Source Geospatial Intelligence

Sample of geolocated tweets referring
Occupy Wall Street.
We have just finished a paper entitled 'Social Media and the Emergence of Open-Source Geospatial Intelligence' for Socio-Cultural Dynamics and Global Security. For those interested below is the abstract:

The emergence of social media has provided the public with an effective and irrepressible real-time mechanism to broadcast information. The great popularity of platforms such as twitter and YouTube, and the substantial amount of content that is communicated through them are making social media an essential component of open-source intelligence. The information communicated through such feeds conveys the interests and opinions of individuals, and reveals links and the complex structure of social networks. However, this information is only partially exploited if one does not consider its geographical aspect. Indeed, social media feeds more often than not have some sort of geographic content, as they may communicate the location from where a particular report is contributed, the geolocation of an image, or they may refer to a specific sociocultural hotspot. By harvesting this geographic content from social media feeds we can transfer the extracted knowledge from the amorphous cyberspace to the geographic space, and gain a unique understanding of the human lansdscape, its structure and organization, and its evolution over time. This new-found opportunity signals the emergence of open-source geospatial intelligence, whereby social media contributions can be analyzed and mined to gain unparalleled situational awareness. In this paper we showcase a number of sample applications that highlight the capabilities of harvesting geospatial intelligence from social media feeds, focusing particularly on twitter as a representative data source.
Selection of geolocated pairs of tweeters and retweeters in Tokyo at the time immediately
following the Sendai earthquake
Full reference:
Stefanidis, A., Crooks, A.T., Radzikowski, J., Croitoru, A. and Rice, M. (2014), Social Media and the Emergence of Open-Source Geospatial Intelligence, in Murdock, D.G., Tomes, R. and Tucker, C. (eds.), Human Geography: Socio-Cultural Dynamics and Global Security, US Geospatial Intelligence Foundation (USGIF), Herndon, VA, pp. 109-123. (pdf)

Wednesday, January 18, 2012

Agent-based Models and Geographical Systems at the AAG

As Agent-based modeling (ABM) within geographical systems is starting to mature as a methodology in geography and across the social sciences. We (Alison Heppenstall, Mike Batty, Mark Birkin, Christopher Bone and Andrew Crooks) have organized several sessions under the topic of  "Agent-based Models and Geographical Systems"at the forthcoming AAG Annual meeting in NY. These start nice and early on Saturday the 25th of February and go until Sunday the 26th.

The aim of the sessions is to bring together researchers utilizing agent-based models (and associated methodologies) to discuss topics relating to: theory, technical issues and applications domains of ABM within geographical systems.

If you plan on attending the AAG, feel free to pass by and say hello. For Saturday, all talks will be in the Carnegie Suite West, Third Floor, Sheraton Hotel starting at 8am. For Sunday,  all talks will be in the Carnegie Suite East, Third Floor, Sheraton Hotel

Agent-based Models and Geographical Systems: Applications (1)

8:00 AM - 9:40 AM, Chair: Mark Birkin

*Neeraj G Baruah, Robert P. Haining Mike Bithell,
*Ateen Patel
*Elenna R. Dugundji & László Gulyás
*Alison Heppenstall & Kirk Harland
 *René Janelle Jordan, Mark Birkin & Andrew Evans
Agent-Based Models and Geographical Systems: Applications (2)

10:00 AM - 11:40 AM, Chair: Alison Heppenstall

*Handi Chandra Putra & Clinton J Andrews
*Regina Ryan
*Sebastien Rey Coyrehourcq & *Clara Schmitt
Agent-Based Models and Geographical Systems: Decision Making

12:40 PM - 2:20 PM, Chair: Andrew Crooks

*David Bennett, Jerry Schnoo, Marian Muste, Silvia Secchi, Deng Ding, Sudipta Mishra & Umashanker Rapol
*Christopher Bone
*Dawn Parker, Tianyi Yang, Qingxu Huang, Shipeng Sun, & Raymond Cabrera
Tyler Bonnell, *Raja Sengupta, Colin ChapmanTony Goldberg
*Roger White
Agent-Based Models and Geographical Systems: GIS and Geocomputation

2:40 PM - 4:20 PM, Chair: Alison Heppenstall

*Majeed Pooyandeh & Danielle Marceau
*Gabriel Wainer & Mariano Zapatero 
*Andrew Crooks, Mark Coletti, Sarah Wise & Keith Sullivan
Christopher McCreadie, David Blackwood, Mark Rounsevell, & *Ruth E Falconer
Agent-Based Models and Geographical Systems: Land Use Change

4:40 PM - 6:20 PM, Chair: Mike Batty

*Shipeng Sun, Dawn Parker, Dan Brown, Qingxu Huang, Tatiana Filatova, Derek Robinson, Meghan Hutchins & Rick Riolo
*Peter Deadman & Raymond Cabrera
*Nicholas Magliocca, Erle Ellis & Daniel Brown
*Fang Wang & Danielle Marceau
*Patrick Harrison & *Seth Spielman
161 Agent-Based Models and Geographical Systems: Methodological Advances

Sunday, 8:00 AM - 9:40 AM in Carnegie Suite East, Third Floor, Sheraton Hotel, Chair: Andrew Crooks

*Sanna Iltanen
*Kenneth Steif
*David O'Sullivan
*Paul Torrens
*Hyeyoung Kim & Chulmin Jun
Agent-Based Models and Geographical Systems: Policy Modelling

10:00 AM - 11:40 AM, Chair: Mark Birki

*Claudio Cioffi-Revilla, Andrew Crooks, Kenneth De Jong, Timothy Gulden, William Kennedy, Sean Luke & Mark Coletti
*Johannes Flacke
*Atesmachew Hailegiorgis
*Amit Patel, Andrew Crooks & Naoru Koizumi
 *Elfie Swerts
Agent-Based Models and Geographical Systems: Urban Networks

12:40 PM - 2:20 PM, Chair: Mike Batty

*Einar Holm & Lena Sanders
*Clémentine Cottineau
Timothy Gulden & *Ross Hammond
*Thomas LOUAIL
*Marie-Noelle Comin
Agent-based Models and Geographical Systems: Urban Simulation

2:40 PM - 4:20 PM, Chair: Andrew Crooks

*Ed Manley, Tao Cheng, Alan Penn & Andy Emmonds
*Huiye Ma, Theo A. Arentze  & Harry Timmermans
*Mark Birkin & Nick Malleson
*Mike Batty & Erez Hatna 
*Denise Pumain

 *Denotes speaker(s)