Helen Couclelis

The role of spatial metrics in the analysis and modeling of urban land use change

The paper explores a framework combining remote sensing and spatial metrics aimed at improving the analysis and modeling of urban growth and land use change. While remote sensing data have been used in urban modeling and analysis for some time, the proposed combination of remote sensing and spatial metrics for that purpose is quite novel. Starting with a review of recent developments in each of these fields, we show how the systematic, combined use of these tools can contribute an important new level of information to urban modeling and urban analysis in general. We claim that the proposed approach leads to an improved understanding and representation of urban dynamics and helps to develop alternative conceptions of urban spatial structure and change. The theoretical argument is then illustrated with actual examples from the urban area of Santa Barbara, California. Some questions for future research are finally put forward to help strengthen the potential of the proposed framework, especially regarding the further exploration of urban dynamics at different geographic scales.

From cellular automata to urban models: new principles for model development and implementation

Integration with geographic information systems (GIS) has helped move cellular automata (CA)-based urban and regional models from the realm of instructive metaphors to that of potentially useful qualitative forecasting tools. Such models can now be fully interactive for exploratory purposes and they can be based on actual data. New problems, however, arise as the formal integrity of the original CA framework is lost through successive relaxations of the assumptions and as the resulting complicated models become increasingly difficult to implement and understand. In this paper I propose that the theoretical problem can find a satisfactory answer in the notion of proximal space and the practical one can be handled successfully within the formalism of geo-algebra, a mathematical expression of proximal space which builds a bridge between GIS data and operations, on the one hand, and traditional robust classes of urban and regional models, on the other.

Cellular Worlds: A Framework for Modeling Micro—Macro Dynamics

Cellular spaces have recently received a lot of attention in computer science and elsewhere as models capable of bridging the gap between disaggregate and aggregate description. Despite their obvious spatial interpretation, standard cell-space models are too constrained by their background conventions to be useful in realistic geographic applications. In this paper, a generalization of the cell-space principle is presented, based on discrete model theory, and then applied to a hypothetical but fairly complex problem of individual decision and large-scale urban change. The paper ends with a discussion of the wider import of this methodology, which has close links with, among other things, bifurcation theory, cognitive science modeling of individual decision and behavior, and other issues of actual or potential interest to geographers.

Exploring the anchor-point hypothesis of spatial cognition*

Abstract The anchor-point hypothesis of spatial cognition, according to which primary nodes or reference points anchor distinct regions in cognitive space, brings together certain frequently reported apparent properties of mental maps: the regionalization and hierarchical organization of cognitive space, and the active role of salient cues in structuring spatial cognition. After a brief overview of the state of the art in cognitive mapping research, the anchor-point hypothesis is first explored conceptually, and then one particular version of it, the ‘tectonic plates’ hypothesis, is made operational. For that second part of the study, cognitive configurations derived from five subjects selected from a larger sample taken in Goleta, California are analyzed using three different methods, and features transcending any method-specific biases are identified. Although not entirely unambiguous, these first results seem encouraging and warrant further research in this direction.

People Manipulate Objects (but Cultivate Fields): Beyond the Raster-Vector Debate in GIS

The ongoing debate in GIS regarding the relative merits of vector versus raster representations of spatial information is usually couched in technical terms. Yet the technical question of the most appropriate data structure begs the philosophical question of the most appropriate conceptualization of geographic space. The paper confronts this latter question in the context of the opposition between the “object” and “field” views of space. I suggest that GIS can turn a rather dry debate into a source of insights regarding the nature of its subject matter by learning from how people actually experience and deal with the geographic world. Human cognition indeed appears to make use of both the object and field views, but at different geographic scales, and for different purposes. These observations suggest a list of desiderata for the next round of thinking about spatial representation in GIS.

Map dynamics: integrating cellular automata and GIS through Geo-Algebra

In this paper the modelling formalism of cellular automata (CA) is generalized and extended within Geo-Algebra, a mathematical generalization of map algebra capable of expressing a variety of dynamic spatial models and spatial data manipulations within a common framework. Map dynamics, that is, the integration of the spatial dynamics reflected in CA and the spatial data handling capabilities of map algebra, constitutes a critical element within a wider project which sets out to formulate a general framework for simultaneously supporting spatial database manipulations and static and dynamic modelling within GIS. Map dynamics can also allow the modelling of additional dynamic behaviours and phenomena such as adaptation, design, learning and gaming not currently expressible as GIS models.

The Certainty of Uncertainty: GIS and the Limits of Geographic Knowledge

Considerable effort has been devoted over the years to fighting uncertainty in geographic information in its different manifestations. Thus far, research on handling inaccuracy, fuzziness, error and related issues has focused for the most part on problems with spatial data and their direct products, typically representations of spatial objects or fields. This paper seeks to broaden the discussion of uncertainty in the geospatial domain by shifting the focus from information to knowledge. It turns out that there is a surprising number of things that we cannot know (or questions we cannot answer) that are not the result of imperfect information. Forms of not knowing are pervasive in domains as diverse as mathematics, logic, physics, and linguistics, and are apparently irreducible. This being the case it may help to explore how these realms of ignorance may affect our efforts. The paper distinguishes three different modes or forms of geospatial knowledge production, and argues that each of them has built–in imperfections, for reasons of logical principle and not just empirical fact. While much can and needs to be done to manage and resolve uncertainties where possible, I argue for accepting that uncertainty is an intrinsic property of complex knowledge and not just a flaw that needs to be excised.

Of mice and men: what rodent populations can teach us about complex spatial dynamics

Models of complex systems need not be themselves complex, let alone complicated. To illustrate this important point, a very simple cellular automaton model of rodent population dynamics is used to generate a wide variety of different spatiotemporal structures corresponding to different forms of equilibrium, cyclical, quasi-cyclical, and chaotic system behavior. The issue of complexity as it pertains to a number of different contemporary scientific fields is then discussed, and in particular its implications for prediction. The discussion ends with some general reflexions about modeling in human geography.

From Sustainable Transportation to Sustainable Accessibility: Can We Avoid a New Tragedy of the Commons?

Accessibility is the geographic definition of opportunity. The opportunity individuals have to participate in necessary or desired activities, or to explore new ones, is contingent upon their ability to reach the right places at the appropriate times and with reasonable expenditure of resources and effort. Up until recently the history of the increase in accessibility at local, regional, and global scales has largely been the history of improvements in transportation. With the advent, spread, and now merging of telecommunications and digital information technologies there exist for the first time viable and often preferable alternatives to physical movement for accessing and engaging in economic, social, or cultural activities. These developments combine with advances in the design and management of physical transportation to create substantially altered forms of accessibility landscapes reflecting profound changes in the meaning of that term itself and its implications for urban and regional structure and function.

Pizza over the Internet: e-commerce, the fragmentation of activity and the tyranny of the region

The question this paper explores is the extent to which e-commerce may be liberating consumers and merchants from the constraints of space (and time) that have traditionally led to predictable regional patterns of retail location. Is distance dead, have the laws of regional organization dissolved away in the age of Internet shopping? Following a discussion of some figures, trends and definitions relating to e-commerce, the paper develops a tentative theoretical framework for the study of this question. First, the fragmentation of activity hypothesis suggests that the activity of shopping can be decomposed into a large number of different sub-activities, some of which can better be carried out physically and others electronically from a variety of different locations. Next, noting that the sub-activity of paying for a purchase is the single most critical one for the survival of a local retail presence, a general game-theoretic model is outlined to help to estimate the relative amounts of physical vs. Internet shopping that would help to safeguard a healthy local retail presence. The paper concludes that e-commerce is not about to end the ‘tyranny of the region’. Regional structure principles remain important, although many familiar analytic approaches may have to be rethought or extended.