Britain From Above

While nothing to do with ABM, some of us at CASA have been doing some voluntary work for a new BBC TV series called Britain from above. Basically we assisted in organising and refining vast hordes of geographic information such as the 2001 Census, the intricate network of railways and then producing fine scale maps which appear on the show after some amazing CGI and graphics work by a professional company. The program looks great:

I particularly like this clip:

More information about the show:

http://www.bbc.co.uk/britainfromabove/

http://news.bbc.co.uk/1/hi/technology/7539529.stm

http://www.bbc.co.uk/britainfromabove/about/experts.shtml

Fractal Cities: available for download

“Fractal Cities: A Geometry of Form and Function” by Professors Mike Batty and Paul Longley is a well written, a must read and often cited book for anyone interested in or writing about fractals, urban modelling and complexity sciences.

In the introduction the authors state that...

“The book presents an initial attempt to apply fractal geometry to cities. In fact, we go beyond this and argue that cities are fractal in form, and that much of our pre-existing urban theory is a theory of the fractal city. As befits a beginning, this book is very much an introductory statement and, as we argue throughout, these ideas are simply crude snapshots of a much bigger picture which we hope others will steer their research towards.

In terms of theory, we show here that the architect's physical determinism concerning the city can be captured and elaborated in terms of fractals while the geographer's concern for the economic theory of location is entirely consistent with the use of fractal ideas. We live in an era when physical determinism is still disreputable as architects and city planners seek to minimize the impact of designs which manifestly interfere with the social and economic fabric of cities in countless unanticipated and undesirable ways. But physical form does determine the quality of life in cities.

We see fractal geometry as providing a new hope for understanding the power of determinism, as well as new methods for enabling the synthesis of urban density with central place theory, new ways of visualizing the impact of human decision-making on cities, and perhaps most of all, new goals for achieving the good society through manipulating and planning city form.”

Professors Mike Batty and Paul Longley have now made their book “Fractal Cities: A Geometry of Form and Function” freely downloadable from http://www.fractalcities.org/

Modelling4All

While still in its early stages, the modelling4All site is worth a look. The aim of modelling4All is to reduce the difficulty and effort needed to make agent-based models therefore enabling non-programmers to collaboratively build and analyse computer models. The project was inspired by sites such as easy to use and user generated sites such Scratch, Flickr and Bamzooki.

modelling4All allows one to create agent-based models over the web, models are constructed by composing and parametizing model fragments (bits of code). The model fragment library can be searched and model fragments can be added and combined to a model to create an agent-based model in a very short period of time by just clicking on the fragment (such as a behaviour) which is required for the task at hand.

This approach allows non-expert modellers to get a feel for the modelling process and allows for a collaborative approach to the creation of agent-based models.

Project Websites:

http://modelling4all.wikidot.com/ (Wiki)

http://modelling4all.nsms.ox.ac.uk/(Code)

http://modelling4all.wordpress.com/about/(Blog)

Agent-Based Modelling for Housing

Today I attended and gave a talk at a workshop on ABM at the 4th International Conference on e-Social Science in Manchester. The title of the talk was “Agent-Based Modelling for Housing” and relates my previous work from my PhD and what I am currently working on. The abstract for my talk is as follows:

Cities play a critical role in our lives, providing habitats for more than half the world’s population in 2008 and this proportion is predicted to increase to over 75 percent by the year 2100. With this growth comes pressure on housing both in terms of supply and location. However, understanding such systems is extremely complex as they are composed of many parts, with many dynamically changing parameters and large numbers of discrete actors interacting within space. The heterogeneous nature of cities makes it difficult to generalise localised problems from that of city-wide problems. To understand urban problems such as sprawl, congestion and segregation, has recently lead researchers to focus on a bottom-up approach to urban systems, specifically researching the reasoning on which individual decisions are made. One such approach is agent-based modelling (ABM) which allows one to simulate the individual actions of diverse agents, measuring the resulting system behaviour and outcomes over time. Furthermore, such models allow us to test different ideas and theories of urban change in the safe environment of the computer, thus allowing scientists to understand urban phenomena through analysis and experimentation, a traditional goal of science.

With the rise of ABM, there has been a growing interest in developing integrated geographical information systems (GIS) and ABM applications. The linkage between the two allows agent-based modellers to have agents related to actual geographic locations and for GIS users, it provides the ability to model the emergence of phenomena through the individual interaction of features in a GIS over space and time.

This paper will explore how agent-based models coupled loosely with GIS can be created to explore housing issues such as segregation, and how residential and employee groups interact to form urban spatial structures characteristic of large cities through a series of illustrated examples dimensioned upon London. Furthermore the paper will discuss the potential of combing ABM with fine resolution data (e.g. Ordnance Survey MasterMap TOIDS to represent individual buildings; MasterMap’s Address layer to populate these building with a number of units, assigning individual agents to each of these units and sales data from the Land Registry to give the units a price) to create models exploring the small scale dynamics of the London housing market from the individual perspective. ABM is inherently suited to such a study as it allows the representation of an heterogeneous population with individual agents having different behaviours and characteristics. For example, the agent’s decisions/behaviour of where to locate is affected by numerous factors. Location is a trade-off between such things as price of dwelling, type of residence and its location, both in terms of neighbourhood and in relation to place of work, all of which vary depending on age, sex, marital status and income. To conclude the paper will present a series of problems and challenges with this approach and ABM in general.

The talk including useful references can be downloaded from here.

Agent-Based Models of Crowd Behaviuor

Agent-based modelling allows us to model individuals and how these individuals interact to form emergent phenomena. A great example of this is crowds. Recently we (people at CASA) have been exploring ways to carryout pedestrian agent-based models in 3D and I just came across this short presentation by Paul Torrens entitled “Modelling Crowd Behaviour” from the O'Reilly Where 2.0 Conference. It is worth watching the talk (15min) as it shows how GIS and ABM can be coupled together and why studying crowd movement is important.

The talk can be watched here.

If you interested in pedestrian modelling and software the papers by Christian Castle might be of interest:

Castle, C.J.E. (2007), Guidelines for Assessing Pedestrian Evacuation Software Applications, Centre for Advanced Spatial Analysis (University College London): Working Paper 115, London.

Castle, C.J.E. and Longley, P.A. (2008), 'Emergency Pedestrian Evacuation Analysis: A Review and Interpretation of Software Applications', in Sui, D.Z. and Cutter, S.L. (eds.), Geospatial Technologies and Homeland Security: Research Frontiers and Challenges, Springer, Berlin.