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), Universit√© 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.