New Working Paper: Agent-Based Models for Geographical Systems: A Review

Its been a while since we published a working paper, especially a CASA one, but this has now changed with the release of a new one entitled "Agent-Based Models for Geographical Systems: A Review." In the paper Alison Heppenstall, Nick Malleson, Ed Manley, Jiaqi Ge, Michael Batty and myself reflect back on the agent-based modeling and their use in geographical systems. 

In the paper we revisit challenges that we first explored back in 2008 (which an earlier version was another CASA working paper) and progress that has been made to address them. We then  explore new challenges within the field of agent-based models especially in light of new new (big) data along with new opportunities (such as data assimilation). If you want to find out more about the paper, below is the abstract and a ling to the paper.

Abstract:

This paper charts the progress made since agent-based models (ABMs) of geographical systems emerged from more aggregative approaches to spatial modeling in the early 1990s. We first set the context by noting that ABM explicitly represent the spatial system by individual objects, usually people in the social science domain, with behaviors that we simulate here mainly as decisions about location and movement. Key issues pertaining to the way in which temporal dynamics characterize these models are noted and we then pick up the challenges from the review of this field conducted by Crooks, et al. (2008) some 12 years ago which was also published as a CASA working paper. We then define key issues from this past review as pertaining to a series of questions involving: the rationale for modeling; the way in which theory guides models and vice versa; how models can be compared; questions of model replication,experiment, verification and validation; how dynamics are incorporated in models; how agent behaviors can be simulated; how such ABMs are communicated and disseminated; and finally the data challenges that still dominate the field. This takes us to the current challenges emerging from this discussion. Big data, the way it is generated, and its relevance for ABM is explored with some important caveats as to the relevance of such data for these models, the way these models might be integrated with one another and with different genera of models are noted, while new ways of testing such models through ensemble forecasting and data assimilation are described. The notion about how we model human behaviors through agents learning in complex environment is presented and this then suggests that ABM still have enormous promise for effective simulations of how spatial systems evolve and change.

Full Reference:

Heppenstall, A., Crooks, A.T., Malleson, N., Manley, E., Ge J. and Batty, M. (2019), Agent-Based Models for Geographical Systems: A Review. Centre for Advanced Spatial Analysis (University College London): Working Paper 214, London, England. (pdf)

Creative Cities

Over the last year I have been working with Ammar Malik and Hilton Root on a small project which explores the relationship between human creativity and urban development via an agent-based model. We have recently just completed a working paper for this project entitled: "Can Pakistan have creative cities? An agent based modeling approach with preliminary application to Karachi" which was published by the International Food Policy Research Institute (IFPRI). For interested readers, below is the abstract to the paper:

Scholars and urban planners have suggested that the key characteristic of leading world cities is that they attract the best and brightest minds. As home to the creative classes, which consist of professionals working in knowledge-based industries, they are the bedrocks of prosperity and drivers of innovation. They not only provide unrivaled educational and professional opportunities, but also the best entertainment facilities such as art galleries, theaters and restaurants. Both through hard and soft infrastructure, residents of these cities enjoy seamless connectivity which fosters human creativity. When combined with population density, socio-economic diversity and societal tolerance, the elevated interaction intensity diffuses creativity and boosts economic productivity. However, rapidly urbanizing cities in the developing world are struggling to maintain adequate service delivery standards. The form and function of many cities are increasingly marred by congestion, sprawl and socioeconomic segregation, preventing them from experiencing expected productivity gains associated with urbanization. We operationalize these insights by creating a stylized agent-based model of a theoretical city, inspired by social complexity theory and the new urban literature. A virtual environment is designed where heterogeneous and independent decision-making agents interact under various policy scenarios, such as greater urban transportation investments and altered land-use regulations. By creating typical urban conditions, we conclude that the combination of mixed land-use, improved access to urban mobility and high societal tolerance levels foster creativity led urban economic growth.

For more details see:

Malik, A.A., Crooks, A.T. and Root, H.L. (2013), Can Pakistan have Creative Cities? An Agent Based Modeling Approach with Preliminary Application to Karachi. Pakistan Strategy Support Program Working Paper 13, International Food Policy Research Institute (IFPRI), Washington, DC. (pdf)

 

New Working Paper: From Buildings to Cities

Duncan Smith and myself have just finished a new working paper entitled "From Buildings to Cities: Techniques for the Multi-Scale Analysis of Urban Form and Function."

Below is the the abstract for this paper:

The built environment is a significant factor in many urban processes, yet direct measures of built form are seldom used in geographical studies. Representation and analysis of urban form and function could provide new insights and improve the evidence base for research. So far progress has been slow due to limited data availability, computational demands, and a lack of methods to integrate built environment data with aggregate geographical analysis. Spatial data and computational improvements are overcoming some of these problems, but there remains a need for techniques to process and aggregate urban form data. Here we develop a Built Environment Model of urban function and dwelling type classifications for Greater London, based on detailed topographic and address-based data (sourced from Ordnance Survey MasterMap). The multi-scale approach allows the Built Environment Model to be viewed at fine-scales for local planning contexts, and at city-wide scales for aggregate geographical analysis, allowing an improved understanding of urban processes. This flexibility is illustrated in the two examples, that of urban function and residential type analysis, where both local-scale urban clustering and city-wide trends in density and agglomeration are shown. While we demonstrate the multi-scale Built Environment Model to be a viable approach, a number of accuracy issues are identified, including the limitations of 2D data, inaccuracies in commercial function data and problems with temporal attribution. These limitations currently restrict the more advanced applications of the Built Environment Model.

The full title of the paper and reference is:

Smith, D. A. and Crooks, A. T. (2010), From Buildings to Cities: Enabling the Multi-Scale Analysis of Urban Form and Function through the integration of Geographical and Geometric Methods. Centre for Advanced Spatial Analysis (University College London): Working Paper 155, London, England. (pdf)

The London Street Network

We have just finished a new working paper entitled "Random planar graphs and the London street network." The abstract for the paper is below:

"In this paper we analyse the street network of London both in its primary and dual representation. To understand its properties, we consider three idealised models based on a grid, a static random planar graph and a growing random planar graph. Comparing the models and the street network, we find that the streets of London form a self-organising system whose growth is characterised by a strict interaction between the metrical and informational space. In particular, a principle of least effort appears to create a balance between the physical and the mental effort required to navigate the city."

The full reference is:

Masucci, A. P., Smith, D., Crooks, A. T. and Batty, M. (2009) Random Planar Graphs and the London Street Network, Centre for Advanced Spatial Analysis (University College London): Working Paper 146, London, England. (pdf)

Neogeography: disseminating geographic content with Web 2.0 technologies

I gave a talk the other day on behalf of the GeoVue project at CASA at the RGS-IBG Annual International Conference in London, and giving a paper entitled "Neogeography: disseminating geographic content with Web 2.0 technologies" in the The e-Social Science agenda: challenges and opportunities for geographers session. The session showcased new e-Social Science developments, explaining and illustrating the opportunities and challenges it poses for geographers, by disseminating the activities of geographers who are engaged in e Social Science. These include applications of e-Social Science in Evidence-based Policy Assessment (EBPA) and other fields of geographies that matter.

The abstract of the talk was:

"In CASA, we are working on Web 2.0 technologies that take geographic content and disseminate to a range of interested users from professionals to non-experts in a way that enables them to interact with the content and to add value to the visualisations that they are able to produce. This is essentially what Web 2.0 is all about – user driven content involving location and place as well as the networks that connect users together. It is the basis of what is currently being referred to as NeoGeography. In this talk, we will illustrate these technologies starting with our developments of virtual cities through our Virtual London model which is within Google Earth move to show how we can user other Google software to enables users to create their own maps using our GMap Creator software and then illustrate how we are building the equivalent of a YouTube for Geographers that we call MapTube. Much of the content that we are working with can also be ported into virtual worlds which represent the next stage of web based development and we will illustrate how we are porting such content from virtual cities and web -based maps into Second Life where we are piggy-backing this content into Nature’s Second Nature space."

Below is a movie of the talk (including all the movies and nice sound provided by Andrew Hudson-Smith's of Digital Urban, you might want to fast forward bits) and a pdf of the talk can be downloaded from here (15MD).


Neogeography: disseminating geographic content with Web 2.0 technologies from Andrew Crooks on Vimeo.

What was interesting is that while the research is of interest to a large online community as supported by interest from the BBC, potentially neogeography is still a niche topic in UK geography. Maybe it suggests that the 'traditional' geographer (what ever this is) is unaware of the latest digital technologies in reaching out for the masses.

On a side note we have a new working paper entitled "Mapping for the Masses: Accessing Web 2.0 through Crowdsourcing" which might be of interest.

Full reference:

Hudson-Smith, A., Batty, M., Crooks, A. T., and Milton, R. (2008), Mapping for the Masses: Accessing Web 2.0 through Crowdsourcing, Centre for Advanced Spatial Analysis (University College London): Working Paper 143, London, England. (pdf)

More information about the GeoVue project, Web 2.0, Second Life etc can be found and Andrew Hudson-Smith's Blog: Digital Urban http://digitalurban.blogspot.com/

News: New Working Paper and ABM in Second Life

Posts have been a bit sparse the last few months, while I have been exploring the worlds of Neogeography, Web 2.0 and Second Life with colleagues from CASA. Andy Hudson-Smith (who writes an excellent Blog called Digital Urban) and myself have just finished a working paper covering some aspects of the above entitled “The Renaissance of Geographic Information: Neogeography, Gaming and Second Life: Working Paper 142”

The abstract is as follows:

“Web 2.0, specifically The Cloud, GeoWeb and Wikitecture are revolutionising the way in which we present, share and analyse geographic data. In this paper we outline and provide working examples a suite of tools which are detailed below, aimed at developing new applications of GIS and related technologies. GeoVUE is one of seven nodes in the National Centre for e-Social Science whose mission it is to develop web-based technologies for the social and geographical sciences. The Node, based at the Centre for Advanced Spatial Analysis, University College London has developed a suite of free software allowing quick and easy visualisation of geographic data in systems such as Google Maps, Google Earth, Crysis and Second Life. 

These tools address two issues, firstly that spatial data is still inherently difficult to share and visualise for the non-GIS trained academic or professional and secondly that a geographic data social network has the potential to dramatically open up data sources for both the public and professional geographer. With our applications of GMap Creator, and MapTube to name but two, we detail ways to intelligently visualise and share spatial data. This paper concludes with detailing usage and outreach as well as an insight into how such tools are already providing a significant impact to the outreach of geographic information.”

Full Reference:

Hudson-Smith, A. and Crooks, A. T. (2008), The Renaissance of Geographic Information: Neogeography, Gaming and Second Life, Centre for Advanced Spatial Analysis (University College London): Working Paper 142, London, England. (pdf)

On another note, Andy, myself and another researcher Joel Dearden are also working on some agent-based models in Second Life. While still rough prototypes, they are looking interesting. We can create, share, and communicate models in a highly visual (3D) and interactive way. The models are simple “proofs of concept” ranging from the Game of Life, Schelling’s segregation model to a pedestrian evacuation model of a building. They are just to demonstrate how virtual worlds could be used by agent-based modellers for outreach purposes. Below are a few screen shots of the models to date. We are currently working on a paper and once written we will give away the code of all the models if anyone is interested in doing such research.

Screen Shot of our Game of Life Model in Second Life:

Screen Shot of Schelling's Segregation Model and GUI in Second Life:

Pedestrian Evacuation Model in Second Life:

While ABM in Second Life is proving interesting we do have an occasional problem of our agents escaping from the pedestrian model and we find them wondering around Second Life:

For more information about Second Life and Andy's work in particular in Second Life see the Digital Urban Blog.

New Working Paper: ABM of Residential Segregation

We just finished a new working paper entitled “Constructing and Implementing an Agent-Based Model of Residential Segregation through Vector GIS”

The abstract is as follows:

In this paper, we present a geographically explicit agent-based model, loosely coupled with vector GIS, which explicitly captures and uses geometrical data and socio economic attributes in the simulation process. The ability to represent the urban environment as a series of points, line and polygons not only allows one to represent a range of different sized features such as houses or larger areas portrayed as the urban environment but is a move away from many agent-based models utilising GIS which are rooted in grid-based structures. We apply this model to the study of residential segregation, specifically creating a Schelling (1971, 1978) type of model within a hypothetical cityscape, thus demonstrating how this approach can be used for linking vector-based GIS and agent-based modelling. A selection of simulation experiments are presented, highlighting the inner workings of the model and how aggregate patterns of segregation can emerge from the mild tastes and preferences of individual agents interacting locally over time. Furthermore, the paper suggests how this model could be extended and demonstrates the importance of explicit geographical space in the modelling process.

Keywords: Agent-Based Modelling, GIS, Residential Segregation, Repast

The full reference is:

Crooks, A. T. (2008), Constructing and Implementing an Agent-Based Model of Residential Segregation through Vector GIS, Centre for Advanced Spatial Analysis (University College London): Working Paper 133, London, England. (pdf)

The paper can be downloaded from here. As always, any thoughts or comments about the paper are more than welcome.

Geospatial Simulation with Repast

After the previous post "ABM–S4–ESHIA Summer School" I thought it would be useful to draw peoples attention to a new CASA working paper entitled "The Repast Simulation / Modelling System for Geospatial Simulation." Which was the basis of talk two from the workshop Mike and I gave.

The abstract to the paper is: 'The use of simulation/modelling systems can simplify the implementation of agent-based models. Repast is one of the few simulation/modelling software systems that supports the integration of geospatial data especially that of vector-based geometries. This paper provides details about Repast specifically an overview, including its different development languages available to develop agent-based models. Before describing Repast’s core functionality and how models can be developed within it, specific emphasis will be placed on its ability to represent dynamics and incorporate geographical information. Once these elements of the system have been covered, a diverse list of Agent-Based Modelling (ABM) applications using Repast will be presented with particular emphasis on spatial applications utilizing Repast, in particular, those that utilize geospatial data.'

If you feel like you might be interested in this paper. It can be downloaded from here. As always any thoughts and comments are most welcome.

Full Reference:

Crooks, A. T. (2007), The Repast Simulation/Modelling System for Geospatial Simulation, Centre for Advanced Spatial Analysis (University College London): Working Paper 123, London, England. (pdf)

New Working Paper

Following on from a previous post we just penned a new working paper outlining in more detail the challenges modellers face when creating agent-based models focusing on geo-spatial phenomena. Note how the challenges have gone from five to seven. The paper is called “Key Challenges in Agent-Based Modelling for Geo-Spatial Simulation.” Below is the abstract:

“Agent-based modelling (ABM) is fast becoming the dominant paradigm in social simulation due primarily to a worldview that suggests that complex systems emerge from the bottom-up, are highly decentralised, and are composed of a multitude of heterogeneous objects called agents. These agents act with some purpose and their interaction, usually through time and space, generates emergent order, often at higher levels than those at which such agents operate. ABM however raises as many challenges as it seeks to resolve. It is the purpose of this paper to catalogue these challenges and to illustrate them using three somewhat different agent-based models applied to city systems. The seven challenges we pose involve: the purpose for which the model is built, the extent to which the model is rooted in independent theory, the extent to which the model can be replicated, the ways the model might be verified, calibrated and validated, the way model dynamics are represented in terms of agent interactions, the extent to which the model is operational, and the way the model can be communicated and shared with others. Once catalogued, we then illustrate these challenges with a pedestrian model for emergency evacuation in central London, a hypothetical model of residential segregation tuned to London data which elaborates the standard Schelling (1971) model, and an agent-based residential location built according to spatial interactions principles, calibrated to trip data for Greater London. The ambiguities posed by this new style of modelling are drawn out as conclusions.”

If you are still interested, click here to download the full paper, any comments or suggestions are most welcome.

Full Reference:

Crooks, A. T., Castle, C. J. E. and Batty, M. (2007), Key Challenges in Agent-Based Modelling for Geo-Spatial Simulation, Centre for Advanced Spatial Analysis (University College London): Working Paper 121, London, England. (pdf)

Exploring cities using agent-based models and GIS

Here is a working paper, which is a modification of the one I presented at Agent 2006, entitled “Exploring cities using agent-based models and GIS.”

Abstract:

Cities are faced with many problems such as urban sprawl, congestion, and segregation. They are also constantly changing. Computer modelling is becoming an increasingly important tool when examining how cities operate. Agent based models (ABM) allow for the testing of different hypotheses and theories for urban change, thus leading to a greater understanding of how cities work. This paper presents how ABMs can be developed by their integration with Geographical Information System (GIS). To highlight this, a generic ABM is presented. This is then applied to two model applications: a segregation model and a location model. Both models highlight how different theories can be incorporated into the generic model and demonstrate the importance of space in the modelling process.

Keywords: Agent-Based Models, Repast, GIS, Segregation, Bid Rent.

The paper is available for download at the CASA website under working papers. Alternatively click here.

Crooks, A. T. (2006), Exploring Cities Using Agent-Based Models and GIS, Centre for Advanced Spatial Analysis (University College London): Working Paper 109, London, England. (pdf)

Principles and Concepts of Agent-Based Modelling for Developing Geospatial Simulations

We have just finished writing a working paper entitled “Principles and Concepts of Agent-Based Modelling for Developing Geospatial Simulations”

The aim of this paper is to outline fundamental concepts and principles of the Agent-Based Modelling (ABM) paradigm, with particular reference to the development of geospatial simulations. The paper begins with a brief definition of modelling, followed by a classification of model types, and a comment regarding a shift (in certain circumstances) towards modelling systems at the individual-level. In particular, automata approaches (e.g. Cellular Automata, CA, and ABM) have been particularly popular, with ABM moving to the fore. A definition of agents and agent-based models is given; identifying their advantages and disadvantages, especially in relation to geospatial modelling. The potential use of agent-based models is discussed, and how-to instructions for developing an agent-based model are provided. Types of simulation / modelling systems available for ABM are defined, supplemented with criteria to consider before choosing a particular system for a modelling endeavour. Information pertaining to a selection of simulation / modelling systems (Swarm, MASON, Repast, StarLogo, NetLogo, OBEUS, AgentSheets and AnyLogic) is provided, categorised by their licensing policy (open source, shareware / freeware and proprietary systems). The evaluation (i.e. verification, calibration, validation and analysis) of agent-based models and their output is examined, and noteworthy applications are discussed.

Geographical Information Systems (GIS) are a particularly useful medium for representing model input and output of a geospatial nature. However, GIS are not well suited to dynamic modelling (e.g. ABM). In particular, problems of representing time and change within GIS are highlighted. Consequently, this paper explores the opportunity of linking (through coupling or integration / embedding) a GIS with a simulation / modelling system purposely built, and therefore better suited to supporting the requirements of ABM. This paper concludes with a synthesis of the discussion that has proceeded.

Key Words: Agent-Based Modelling (ABM), agent-based models, geospatial / spatially explicit modelling, verification, calibration, validation, Geographical Information Systems (GIS), linkage (coupling or embedding / integration).

The paper is available for download at the CASA website under working papers. Alternatively click here.

Full Reference: 

Castle, C. J. E. and Crooks, A. T. (2006), Principles and Concepts of Agent-Based Modelling for Developing Geospatial Simulations, Centre for Advanced Spatial Analysis (University College London): Working Paper 110, London, England. (pdf)