modelling development of urban form in residential areas with system of cellular automata-enhr2010...

8/8/2019 Modelling Development of Urban Form in Residential Areas with System of Cellular Automata-ENHR2010 Ognen M

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URBAN DYNAMICS & HOUSING CHANGE - Crossing into the 2 nd Decade of the 3 rd

Millennium

Modelling Development of Urban Form in Residential Areas withSystem of Cellular Automata

Ognen MARINAUniversity Ss. Cyril and Methodious in Skopje, Faculty of Architecture, Bul. Partizanski odredi, 24

Skopje, Macedoniae-mail: [email protected]

Abstract

Complex order of urban form is created through a process of dynamic transformations. The emerging form is aresult of a process of morphogenesis as a historically embedded process of creation and adaptation. This processcreates order through interaction of the inherent order of the form and the order of the process and society itself.

In our research process of form creation is determined as a system of elements and locally defined rules for their combinations. Condition of each of the elements is set by its interaction with all the other elements of the systemand therefore is locally determined. Cellular automata are the system that is used for representation of the

dynamic and morphogenetic behaviour of urban form. This system is coherent with the nature of the phenomenonthat represents. The result is a model of development of urban form that elucidates forces and processes that arebeyond materiality of urban form and reveal the configuration aspects of processes that are shaping our cities.Traversing diverse historical and contemporary settings, we seek to explicate spatial distribution and models of urban form in their relevance to the society and city itself.

Keywords: Urban form, Modelling, Dynamic Transformations, Cellular Automata.

Introduction: Process VS. Fixed Typology

Urban form as a dominant physical structure in urban environment determines many aspects of our everyday life activities. It is part of everyday experience for a significant part of the human kind andis the way humanity expresses its culture and society in spatial manner. Dominant typologies that servedto legitimized the production of urban form through architecture since eighteenth century were either

based on the idea of return of architecture to its natural origins a model of primitive shelter as animitation of the order of Nature, or emerging as a result of Industrial era architecture as a process of

production of functional parts (Vidler 2003). In these concepts urban form is just an inert receptor of externally imposed order and therefore its form is predetermined by fixed typologies (Delanda 2004).

ENHR 2010, 4-7 July, ISTANBUL 22 nd International Housing Research

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WS-25: HOUSING AND INNOVATION

Most of the paradigms were delegitimized with the fact that the origin of the order of urbanform was position outside the system instead to acknowledge the inherent order of the system asfundamental for form generating process.

Urban form exists simultaneously as a historically embedded process of creation of form and as an object product of that process (Hillier, 1996). The nature of urban form is inherentlydynamic and can not be determined by fixed types regardless of vastness of number of types. Therefore,existing concepts in theory of cities based on fixed typologies does not provide solid ground for understanding the process of creation of form and the phenomenon of urbanity in general.

Solution of this situation can be reach only by radical change in point of view: urbanform not to be conceived as a static system of predetermined ideal forms but rather as a dynamic systemof changes that will generate a complex result. The emerging form will be a result of a process of morphogenesis as a historically embedded process of creation and adaptation (Holland, 1996). This

process creates order through interaction of the inherent order of the form and the order of the processitself.

1. Order Creation Process and Generative restrictions

The idea of architectural and urban form as order that is inherently connected with the societyand culture of mankind is in very base of our idea of urban form as a complex and generative system. Itis this theoretical stand that enables us to determine process of analyzing and in the same time genesisof architectural and urban form through process of creation of order that is inherent to the system andthe process itself.

The source of this idea of architecture as a representation of particular social order and theformal tools that are enabling it is within the notion of classical architecture. Name of the classicalarchitecture is connected to and derived from the social order of classici, the highest in rank in socialstrata of ancient Rome (Tzonis, 1986). The order in classical architecture is determined by formal toolsor techne of composition (Aristotle) that are connected with order and distribution of matter (Cicero).

The form is predetermined by formal typology organized and transferred in reality through

canonical system of formal conventions and is encoded by social conventions through which buildingobtains social relevance within the built and social environment. The process of order creation and itsformal tools is the way that this social relevance is obtained (Tzonis) and the society and culture isrealized in spatial manner.

In a formal sense architectural and urban form can be defined as a set of elements and set of rules that determines the way in which this elements combine and are organized in process of creationunifying whole. The problem with this definition of form and process of its creation is that it does not

provide guarantee that elements of form organized by obeying the defined rules will create logicalentities that can be recognized as architecture or urban form. Therefore the real source of order creationin the process of form creation is not in the definition of elements and rules for their combinations butrather in the restriction that are imposed to a formal system. Generative restrictions are given as anaffinity of elements of the formal system to combine with one set elements more often rather than withsome other group of elements. This idea suggest that the emergence of order is not dependant oncombinatorial rules and that the same is not imposed from top-down by some central principle but israther embedded in the elements of the system of form. Tendency some of the elements to createcombinations with particular set of elements is called by linguist George K. Zipf (Delanda, 2003) as adegree of crystallization. It exhibits the degree of connectivity between particular group of elements tocreate logical and semantically coherent entities as a result of existence of locally defined affinities andrestrictions of elements.

Order creation process emerges from elements inherent logic and is defined by locallydetermined restrictions that because of its generative potential are generative restrictions. Locallyembedded rules and restrictions that determines which of these combinations will result in a form thatcan be recognized as urban form are the very base for better understanding of the phenomenon of thecities and not just the combinatorial rules.

Therefore order creation process in the context of architecture and urban form can beunderstood as a locally driven process of relationships between elements within the system. This


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process of creation of logically coherent unities requires existence and definition of urban form as asystem of objective and logically ordered relationships. For that purpose we will define architecture andespecially urban form dominantly as a system of spatial relations or even better as a configurations. For Bill Hiller (1996) this spatial configuration of urban form is the strongest link between form, context

and the society. It is through configurational aspect of urban form that culture and society is realised inspatial manner and not through superficiality of form surface and architectural stiles.In architecture and urban form physical process of creation of boundaries is analogue to a

process of creation of categories. Creation of one category interior space determines the existence of another distinctive category that is exterior space. These relations are not just a physical fact but rather have logical nature although they are created as a result of physical process. Objectivity of relations

between these categories is called configurations. This attribute of architectural and urban form enablesus to exhibit and research the configurational aspects of form and function within their objective andabstract comparability. For that reason we will observe architectural and urban form exclusively throughits configurational aspect and its double nature.

2. Configurational aspects of Urban form

Built environment and architectural objects as a part of it are the biggest and most complexcreation of mankind. Its complexity and vastness comes from a process of continous creation of architectural form not only as a physical objects but as a proces of creation of spatial, social an culturalrelations. Dependance of form creation process on these configurational aspects of architectural formdetermines the importance of understanding the same.

Architectural objects can be determined as a construction of physical and material elementsordered in stable shape (Hillier, 1996). As a result of this process of construction a spatial relation

between interior and exterior space is created. This relation generates the basic spatial configurationsthat differentiate architectural form from any other human activity. (Fig.1)

Fig.1: Creation of spatial configurations

This proces of transformation of preexisting condition and creation of new order within the physical reality and new configurations of space determines the social meaning and relevance of act of construction and form creation. With this architecture becomes socially relevant and meaningful.Therefore architectural objects because of their nature can not be determined only as physical objects

but through their spatial and organizational aspects as a dominantly configurational structures. With thissystem of architectural form becomes the spatio temporal manifestations of configurational order realised througs physical elements.

The complexity of the system comes from a locally driven set of simple rules that inducecontinous adaptations and changes on local level but with impact on overall condition of the system. Itenables us to generate complex and novel shapes and configurations as a result of dynamic, nonlinear


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and locally driven morphogenetic process. These new structures are more than a sum of their parts andare not predetermined or preconsived by any means. They are result of a hystorically embeded processof creation which is driven by locally conditioned simple rules.

3. New Paradigms in Order Creation Process

In order to construct a model of dynamic development of architectural form first we have toestablish some theoretical preliminaries and to address some new concepts and paradigms.The idea of architectural form as an inert receptor of predetermined form originates in part from thedominant concepts of representation. Formal elements of architectural form represented in Cartesianthree-dimensional space are determined by fixed coordinates of their points within the system. Withthis, elements of architecture are nothing more than a copy of ideal, platonic forms liberated of any traceof inherent order (Delanda, 2008).

As an opposition of these concept is the idea of architectural form as dynamic and historicallycontingent system. The order of the system emerges as a result of a process of morphogenesis. Creation

of form is a process of individualization where every particular property of an distinctive element is aresult of acumulation and interaction of different influences, conditions and restrictions, process that iscompletle dependant on specific and historically contingent details. Adjacent to this concept istopological paradigm where identity and position of each of the elements or parts of it within the systemare determined exclusively through its relation with all other elements within the system. By this,identity of the element is generated through decentralized set of relations within the structure of thesystem and without interference of any external centre of identity or shape. Since there is no centre todictate the predetermined form of elements of the architectural and urban form, formal order isdetermined only by locally defined relations between the elements. This decentralized order generating

process is distributed within, and in the same time dependant on a population of elements . So, instead of thinking in terms of one shape defining centre the system should be understand in terms of population of elements. This multiplicity (Deleuze, 1988) of elements and local relations that create the order of the

system are the source of process of morphogenesis. In situation when system of architectural form isdefined as a population of elements we always have to specify the process of creation first in order tohave the idea of the overall form of the system. This process is inherently historic and is based onexistence of differences between the elements. Without existence of these productive differences thatraise the process of adaptation and levelling of differences within the system and diffusion of novel andcreative solutions within the population of formal elements there would not be any morphogenesis.

These are the new paradigms and new concept that should enable us to construct a model of dynamic development of architectural and urban form.

4. Model of Dynamic Transformations with System of Cellular Automata

So far we have establish that the process of form creation is determined as a system of elementsand locally defined rules for their combinations. Condition of each of the elements is set by itsinteraction with all the other elements of the system and therefore is locally determined. Rules andmechanism of this system are applicable to all the levels of complexity of the phenomenon of architectural or urban form indifferent to the spatial size of the entity. This model of form is inherentlydynamic and on the basis of set of elements and local rules generates complex order that will identifysystem of form as more than just the sum of the elements.

Cellular Automata are the systems that are constituted of populations of cells that create emergentorder and configurations on base of locally driven rules and relations between them. With use of cellular automata we can establish satisfactory level of simplification of process of form generation and in the

same time to preserve the complexity of the result. The process of morphogenesis is represented as asequence of activities of cells whose present condition (simple as on or off, black or white, built or not)


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is always determined by previous condition or the condition of their neighbouring cells which modifiesthe shape of the configuration and the structure at large. Formally it can be defined as: SH (t+1) = Ft(SH (t), SU (H) (t)) (Portugali, 1999).; where SH (t) is a present condition of a cell H, U (H) is a cellneighbourhood H, SU (H) defines the set of conditions of neighbourhood cells (configuration of the

neighbourhood) and F is a rule of transformation developing in time t, according to which the newcondition of H is created. (Fig.2)

Figure 2. Sample of posible states of cell in Cellular Automata

With creation of a basic element of architectural form spatial cell the elementaryconfigurationally relation between inside and outside is created. Through process of addition morediscreet elements are created that generates complex configurations of physical and spatial structures.These elements and their spatial relations and configuration of the system in general are representedthrough system of cellular automata (Fig.3).

Figure 3. Iterations of Cellular Automata model of Architectural form

Comparative syntactic models for each model of cell automata represent the

permeability and connectivity of the spatial configurations and confirms the configurationally aspects of the system that is represented through this model. Change in only one segment of the system results in


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change of the overall organization of the model. Analysis of process of development of configuration of any set of the elements will enable us to determine the rules according which these particular structuresis generated. This defines cellular automata model of architectural form as analytical tool but in thesame time a model with form generation capacity. 3D images of representation of iterations of thesystem of Cellular Automata as a model of architectural form gives even better idea of spatial andgenerative capacity of the model (Fig.4).

Figure 4. 3D representation of Cellular Automata model of Architectural form

5. Model of Development of Urban form

Model of urban form that we have developed is based on a certain simplification of reality because of the simple fact that the model of reality that represents the reality in whole complexity wouldnot provide any new information apart from our everyday experience and even less analytical or scientific insight of the phenomenon. Therefore it should fulfil certain preconditions.

Model of urban form should map the dynamic behaviour of urban form that is not only to map thefixed position of elements of urban form in time but rather to have the potential to define the wayelements of urban form change in time. Only in that case model of urban form would not be related tofixed and stable conditions of elements in time but would refer more to the dynamics of development,change and adaptations of the system. The innovation of this approach is that the elements and relationsof the model representing the development of the system of urban form would emerge exclusively as

locally determined and decentralised process of complex order creation.On the basis of our previous explication we have determined system of Cellular Automata as most

appropriate for modelling dynamic change of urban form as a process of creation of complex order.With this model form of the system is always a result of non-linear historically embedded process of dynamic transformations.

In order to establish such model of development of urban form it is necessary to define certain postulates of the model. First, existence of at least one basic spatial element is necessary in order tohave basic spatial relations of inside-outside space that will create a basic spatial configuration. Second,contact between two cells will always be on one of its sides. Third, relation between discrete spaces isalways through contact between two cells. This is only an initial, starting and fixed condition of themodel and we are mostly interested in dynamical aspect of the system that we are modelling. For that

purpose we have to define set of locally determined and embedded rules that will shape the behaviour of each of the elements of the system. These rules will act as a combinatorial restrictions and affinities of the elements.

The condition of each of the cells will be determined as result of interaction and accumulation of different locally embedded rules rather than by an exterior, order imposing centre. In this model use of cellular automata is additionally justified with spatial and representational similarity between elementsof urban form (buildings, lots, streets, squares and others) and discrete cells as elements of the model.Further more condition of each of the elements of urban form that is beyond its formal aspect (propertyrights, legal status and others) can be represented with binary determined condition of the system of cells.

In order to create more realistic model of development of urban form in process of creation andimplementing set of local rules of transformations of the elements of the system we traced and mappedthe types and tendencies of transformations observed in two residential settlements in Skopje. Researchwas performed on two urban residential areas in city of Skopje that are constituted of residentialhousing and have two different and distinct formal and historic backgrounds. First observed case study


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(Madjir maalo) is dated from nineteen century and is part of the historic milieu of Skopje. It hasdeveloped as a result of historic and first planned urban structure of Skopje and vernacular architecture.The second case study (Taftalidze) is a residential area developed after the earthquake in 1963 as anexample of modernistic urbanism with conceptual mixture of urban sprawl. Both areas have gone

through significant change and process of transformations that can be detected and explored. On the base of detailed morphosyntactic analysis of both residential areas we have determined main rules andtendencies of development of urban form in these residential areas in process of creation of model of development. Then, these rules that are locally determined and are affecting the condition of each of thecells of the system were defined and transferred into the simplified syntax of systems of Cellular Automata.

Transformations where the dominant process of transformations is determined as a tendencyfrom elementary organization to a complex aggregation is the base for the fist rule transferred into thesimplified syntax of cellular automata: if the cell is with status black (1) than at least one of itsneighboring cells with status white (0) will become black (1). (Fig.5)

Figure 5. Rule nr.1

Second rule is based on another process of transformations with main tendency to createsymmetry (symmetrical organization) out of asymmetrical pre-condition of the elements of the system.Second rule is defined as: if the cell with status white (0) has contact with at least two other cells with

status black (1), than it will become black (1). (Fig.6)

Figure 6. Rule nr.2

If we impose only these two rules on the system it is very immanent that the system will fill thewhole system field with black cell elements and once overfilled will reach equilibrium without any

possibility for further development. Therefore it is necessary to introduce third rule that will bereductive and will act as restriction of black cell production. Third rule is: if a cell with status black (1)


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has contact with at least three other neighboring cells with status white (0), than it will become white(0). (Fig.7)

Figure 7. Rule nr.3

Implementation of this rule can be understood as an implementation of restrictions for development of form that in reality can be recognized as formal, economic or legislative restrictions. Finally, in order tomodel the whole complexity of the system it is necessary to introduce another variable into the processof iterations. For that reason we have determined fourth rule as set of rules defined by John Conway as aGame of Life.

It is obvious that application of only one of these rules into the model of urban form willgenerate relatively linear and expected result. But with simultaneous application of multiple of rules,their interaction and influence within the system, the number of possible solutions will rise beyond

predictability of human mind and accessible tools. (Fig.8)

Figure 8. Sample of 3D and 2D representation with syntactic diagram and Total and Medium depth indicators


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In order to follow the development of urban form beyond its formal representation syntacticdiagrams and degree of connectivity of particular configuration is given as adjacent to the 3Drepresentation of cell aggregation. After only several iterations of the system within the model of development it is possible to detect emergence of complex configurations. What is most important is

that complex order of these configurations is created on base of simple and locally defined rules, wherenone of them is defining the global form and condition of the system. And yet the global outcome of theform of the system is highly complex.

Generally, some tendencies within the system can be recognized. First, regardless of the initialcondition of the system of cells it is evident that tendency of creation of compact forms is dominant.Second, this compact forms have tendency to pertain within the system for some period of time. Third,

periodical oscillations of size of these aggregations suggest that there is a high possibility of existenceof attractors within the system. (Fig.5)

Figure 5. 3D representation of iterations of Model of Urban form in Residential areasAll this tendencies are inherent to the system, are result of locally embedded simple rules and

are exhibiting generative capacity of the system for creation of complex spatial order of elements. It isalso obvious that most of the generated spatial configurations would not survive the reality test and their similarity with real situation can vary, but complexity of generated formal and spatial configurations areindicative enough to obtain necessary level of scientific pressure to proceed with further research of

potential of this model of development of urban form.

Conclusion

Plausibility of this model of development of urban form is confirmed on several levels. Onconceptual level it is constituted of elements that are organized and defined by locally driven simple


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rules that generate complex behaviour or complex configurations in our case that are more than sum of their parts. Form of the elements in time t+1 is determined according to the condition of all elementswithin the system given in time t, and set of rules of transformations. This confirms that this model of development of urban form represented with cellular automata is based on principle of transformationand productive differences. Final result of the model is a form of the elements that is a product of

historically contingent process of accumulation of transformations and adaptation within the system.Therefore Cellular Automata are most appropriate system for modeling dynamic development of urbanform and morphogenetic behavior of architectural form. This system is coherent with the nature of the

phenomenon that represents. Construction of a model of dynamic development of the system of urbanform with use of Cellular Automata should enable us for deeper insight into the process of morphogenesis, better understanding of phenomenon of cities, but above all better understanding of results and consequences of our actions into the world that we live in.

References

Vidler, Antony. (2003) The Third Typolgy. in Alexander R. Cuthbert. Ed. Designing Cities. Oxford, BlackwellPublishing.

Delanda, Manuel. (2004) Intensive Science and Virtual Philosophy. New York. Continuum.

Hillier, Bill, Hanson, Jullienne. (1996) Space is the Machine A Configurational Theory of Architecture.Cambridge University Press. 45-46.

Holland, John H. (1996) Hidden Order: How Adaptation Builds Complexity. New York. Basic Books. 3.

Tzonis, Alexander, Liane Lefaivre, Classical Architecture, The Poetics of Order, The MIT Press,1986, 1.

Aristotle, Art of Rhetoric, Harvard University Press, Cambridge, Massachusetts, 1975, bk.I, ch.II, para.I.

Cicero, Ad Herennium, Harvard University Press, Cambridge, Massachusettes, 1954, bk.I, ch II, para.3.

Delanda, Manuel. 2008 Deleuze and the Genesis of Form, Manuel De Landa, An Annotated Bibliogarphy,viewed on 18 September 2008, http://www.cddc.vt.edu/host/delanda/>

Deleuze, Gilles. (1988) Bergsonism. New York. Zone Books.

Portugali, Juval. (1999) Self-Organization and the City. Springer-Verlag. Berlin.


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Batty, Michael. (2005) Cities and Complexity: Understanding Cities with Cellular Automata, Agent-Based Models, and Fractals, Cambridge, Massachusetts, The MIT Press.


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modelling development of urban form in residential areas with system of cellular automata-enhr2010...

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