Project MAGIC - Spatial Simulations through the integration of Geographic Information tools with Multi-Agent Systems Cédric Grueau, CVRM – Centre of Geo-Systems, Technical Higher Institute Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
[email protected] Armanda Rodrigues Dep. Informatics, Faculty of Science and Technology New University of Lisbon, Quinta da Torre - 2829 - 516 Caparica, Portugal
[email protected] António Gonçalves Hydraulics Dep., National Laboratory of Civil Engineering Av. do Brasil 101, 1700-066 Lisboa, Portugal
[email protected] Introduction The development of computational simulations has arisen from the need to study phenomena for which no explicit model has been developed (Barrett and Rasmussen, 1995). The methods used have evolved from the traditional techniques of simulation, involving mathematical and stochastic models, to some more recent approaches, which have addressed the limitations of the numerical ones (Ferber, 1994). This type of approach was initiated with work in cellular automata, which has evolved into what are now called Individual-Based Models (IBM), one thread of which being multi-agent systems. Multi-agent simulations enable the representation of situations in which individuals have complex and different behaviours, to study the global consequences that arise as emergent structures resulting from the interaction processes (Ferber, 1994). Beyond the power of cellular automata, agent simulations enable interaction and communication between the actors in the process and facilitate negotiation processes among them. Moreover, individuals in the simulation are considered as hierarchical structures, which contemplate fine-grain entities belonging to lower level structures. There are several advantages to using this type of approach while studying spatially-mapped phenomena and it is clear that the implementation of simulation models using multi-agent systems would benefit from the access to common operators available in Geographic Information Systems (GIS) packages. Recent developments into commercial GIS packages are characterised by the use of objectoriented (OO) technology. New GIS applications can thus represent and manipulate spatial features as objects, whose state and behaviour can be customised, extended or completely reformulated. The characteristics of agents are also primarily OO. This means that it is currently possible to develop OO architectures involving entities endowed with proactive behaviour ("agentified") as well as spatially-aware. Integration needs felt by scientists trying to use their spatial data as input for their computational models can now be handled transparently. In spite of these developments, it is common practice in agent simulation architectures to have an import facility that reads data from one specific GIS format. This can become awkward if the aim of the work is to disseminate the simulation tool. On the other hand, to implement agentbased simulations inside a GIS may be possible (by using the package's programming language of choice) but can also be limiting if the aim is to endow agents with learning facilities.
Although these issues have been previously addressed by researchers (Westervelt, 2002) it is still not clear what is the best approach in integrating these two types of technology, with the aim of creating spatial agent simulations. This paper addresses these issues in the context of Project MAGIC - Multi-Agent Geographic simulations based on Interoperable Components, which aims to study the possibilities for including spatial analysis tools (characteristic of GIS) in agent-based simulations. This study involves two perspectives: − The implementation of necessary GIS operators in existing successful agent architectures; − The inclusion of agent facilities in a GIS package (either by implementation or through interoperability) These two possibilities will be applied in the implementation of a simulation of environmental impact problems for Gestilamas, a Portuguese professional association of natural stone industry. Project MAGIC Project MAGIC - Multi-Agent Geographic simulations based on Interoperable Components is a three year project (started in October 2002), funded by the Portuguese Foundation for Science and Technology (Fundação para a a Ciência e Tecnologia) and its organization is based on three objectives: Firstly, the development of tools that will enable the creation of adaptive agent-based simulations where each agent can improve its performance through learning and embedded spatial analysis capabilities. Previous work in this area has already demonstrated the added-value given by agent-based systems in simulating complex systems where the spatial dimension is of major importance (Rodrigues, 1999; d’Aquino et al, 2002; Torrens, 2002). Secondly, and in order to achieve the former, it will be necessary to develop a methodology for using the multi-agents systems approach while endowing agents with a geographic analysis capacity. This objective should be achieved through interoperability between agent implementation platforms and geographic information systems. Finally, the project will involve the implementation of a framework, which will follow the developed methodology and will enable the creation of agent simulation where agents can use spatial analysis operations to determine their future actions in the simulation. Agent-based Simulations and GIS Until recently, Geographic Information Systems (GIS) have been widely used for the storage, retrieval, analysis, and display of large volumes of spatial or numerical types of data, being particularly adapted to environmental modelling and land planning. In spite of this, commercial packages were limited in the iterative exploration of dynamic and complex relationships, which did not facilitate the development of embedded complex models (Manson, 2000). Agent-based simulations have been growing since natural sciences researchers started to use very simple structures to create simulations of global emergent phenomena. These early attempts evolved into methodologies where it was possible to study emerging behaviour resulting from societies of reactive agents (Reynolds, 1999; Ferrand, 1995). Reynolds (1999) identified these societies as Individual-Based Models and described a series of examples where the use of simple agents were the basis for the description of complex global behaviour. Because behaviours are not linear, the modelling of elements, whose organizational structure or working mechanisms are unknown, becomes difficult. Agents - or multi-agent systems represent a suitable technique to model these behaviours. Previous research works have underlined agents' capabilities in the handling of spatial problems and have shown how MAS can help identify emergence in complex spatial phenomena (Rodrigues 1999). Two examples of platforms that have been developed for MAS simulation implementation are SWARM (Minar et al 1996) developed at Santa Fe Institute, and CORMAS (Bousquet et al, 1998). The use of multi-agent systems to solve spatial problems is currently an active thread of research with examples from territorial management (Ferrand and Deffuant, 1999), to flood risk management (OIEau, 2001) and prevention (Cemagref, 1998). Other threads include the
simulation of land use/cover change (Manson, 2000) and landscape change processes (Westervelt and Hopkins, 1995). The integration of the technology created to realise these simulations with existing GIS is fundamental and limitations in the connections with GIS packages have led to limitations in the results of the work itself (Lieurain, 1998). In spite of this, until the present date, very few efforts have been made to transparently integrate multi-agent based technology with GIS. Communication between the two types of system is still realised as the exchange of information layers, which the simulation tool imports or exports (Guerrin et al. 1998). This type of interaction is usually awkward, slow and difficult to maintain or modify. Moreover, the data formats accepted are few, mainly the ones generated by the GIS packages the authors use. Recent developments have enabled the possibility of, as stated by Westervelt (2002), embarking on a next level of integration, in which GIS operation will be handled through subroutine calls and object methods rather than system calls. This fact creates the opportunity for the work to be developed in the context of this project. Moreover, the use of interoperable GIS technology in commercial packages (mainly of COM map components inside the simulation environment: Itami et al, 1999) has enabled the definition of geographic features as full objects with a specific state and behaviour, which can be customized, extended or reformulated. Further on, it is technically possible to incorporate agent behaviour into these objects and develop simulations with some spatial characteristics. The last generation of GIS tools now includes an extensible object-component model which can, not only enable the creation of active agents transparently with the GIS architecture, but also the complete customisation and extension of the packages (Johnston, 2000). One of the ways in which project MAGIC will be exploring these GIS object-component models is through the concept of WEB mapping and WEB services. This means that MAS (multi-agent systems) will access geographic information data through a WMS (Web Map Server), which can currently make available, not only a process for accessing layer maps, but also a set of GIS operators (e.g., GIS querying, network analysis) to manipulate the data. These operators are accessed through an appropriate XML request sent to the WMSs, which will generate the appropriate response. In this way, MAS are separated (decoupled) from the GIS tools. Modellers, scientists, software developers or commercial product makers will have a range of possibilities in the choice MAS packages as well as GIS tools (object components). Figure 1 presents the main interoperable components in this approach.
Figure 1 – Main interoperable components of the proposed MAGIC architecture
The part described as application can simply be a standalone application, built in a specific programming language (e.g. JAVA, C++, Smalltalk, etc.), or a web server, enabling the implementation of the integration of MAS with GIS tools as a Web service/mapping. This integration approach is flexible, platform independent, and it enables the choice of the right component for each functionality. Case-Study - a multi-agents system for the management of environmental impacts produced by natural stone industry From extraction to transformation, the production cycle of natural stone involves many industrial actors modifying its physical state and geographic localization to transform stone into valuable material such as ornamental stone for construction. In Pêro Pinheiro region – Portugal, the stone transformation industry is atomized into hundreds of firms annually producing thousands of tons of mud. The management of these wastes is performed individually into deposits producing a strong regional impact. Each industrial uses its own technological solution is organized and do not always behave according to rational patterns. This complex planning problem gathered scientists from Technical Higher Institute in order to come up with solutions and alternative. Multi-Agent Model appeared to be an adequate tool to simulate alternative management options for the industrials, modelled as agents. The model produced aims at reducing the cost of wastes management and the environmental impacts by testing alternative localization, possible acquaintances, and potential environmental normative. This particular case study, as many others, includes a strong component of geographic analysis. It requires GIS capabilities to reference, store and analyze the information not only before and after but also during the simulation. A first implementation of a Multi-Agents model coupling the Cormas Platform (see Bousquet et Al, 1998) with the ArcView GIS Software has been developed with several limitations identified. This first implementation answered some of the industry’s need. It appeared necessary to push forward the technological implementation of the model in order to overcome communication problems between MAS and GIS. The next step is to implement this model on the interoperable platform to develop. The two implementations will be compared in order to enlighten the improvements such a technology may afford. The availability of a spatial agent-based simulation framework with GIS capacity will enable a new perspective in the evaluation of the use of natural resources. Agent systems enable the implementation of simulations where it is possible to evaluate situations under different perspectives according to relevant actors. Moreover, it is possible to enable interactions between different actors in order to explore the social and natural dynamics of the system on a long-term basis. The coupling with GIS will enrich the functionality and behaviour available to the simulation system, which would be difficult to provide within each individual technology (Itami, 2002).
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Biography Cédric Grueau is a PhD Student at the Centre of Geo-Systems of the Technical Higher Institute, Lisbon Technical University. He has been collaborating in Land Management and Geographic Information related projects for 8 years. He has research interests in Agent modelling, spatial reasoning and GI visualisation.
