Stitching together the fabric of space and society: an investigation into the linkage of the local to regional continuum

To date, space syntax models have focused typically on relatively small areas up to the city scale. There have been very few models that take into account the entire network up to the regional scale, so the cumulative effects of micro-scale connections on regional networks is unknown, and the performance of the regional network as a function of the local area cannot be assessed. As such, a complete understanding of the ways in which regional centres are co-dependent and cities relate to their surrounding sub-centres is lacking. This study models the entire road network at the regional scale, by dispensing with axial lines entirely and moving to a road-centre line model of the UK, the Ordnance Survey's Integrated Transport Network (ITN) layer. This layer includes the topological connections between roads, so that a complete topological model of the road network including the directionality of streets can be constructed quickly. A region of the North of England - including Manchester, Bradford, Sheffield and Leeds - is analysed. Regional level angular analysis is shown to correlate well with overall movement in the network, while local level metric analysis is shown to correlate with the population density. It is hypothesised that combined measures that link the global to the local will uncover discontinuities in the continuum of space, and that these disruptions to the network will correspond to social deprivation. However, although such discontinuities exist, experimental linkage of the analysis to deprivation indices by census areas shows little conclusive evidence. In particular, it is clear that the complex web of spatial factors uncovered need investigation with more sensitive tools and smaller units of aggregation. The study highlights the need for a set of combined measures using microscopic spatial, economic, demographic, and land-use data, in order to further understand the relationship of spatial factors with social activity, while reinforcing standard space syntax results at the regional level

Isovists, occlusions and the exosomatic visual architecture

Recently, simulation agents (or animats) using an exosomaticvisual architecture (EVA) have been shown to correlate well with ob-served pedestrian movement in both building and urban environments.An EVA uses a grid overlaid on a two-dimensional plan of a system torecord the locations visible from the current grid square. The agents areallowed to roam freely in the environment, and lookup visual informationfrom the EVA in order to guide them through the plan. This allows manyagents to navigate concurrently using visibility relationships. However,while good correlation between observed physical and virtual systemshas been shown, experiments to date have been based on agents whichmove stochastically to visible locations. This leads to them congregatingin large open vistas, where there are more visible locations. In contrast,when people are observed, they tend to follow the edges of spaces tomove or take direct routes across open spaces to the far side. Here wehypothesize that rather than using open space to guide them, people in-stead use the visual clue of an occluding edge to indicate where furthermovement potential may lie. We supplement the information in the EVAwith details of the isovist at each location, to supply the locations ofoccluding edges from each grid square. We show that these new agentsfollow paths much more similar to observed pedestrians using an openspace. We speculate that the invariance of the occlusion points within aplan may thus lead to an economic skeletal mapping of the environment,and possible basis for a cognitive map

Analysing the visual dynamics of spatial morphology

Recently there has been a revival of interest in visibility analysis of architectural configurations. The new analyses rely heavily on computing power and statistical analysis, two factors which, according to the postpositivist school of geography, should immediately cause us to be wary. Thedanger, they would suggest, is in the application of a reductionist formal mathematical description in order to `explain' multilayered sociospatial phenomena. The author presents an attempt to rationalise how we can use visibility analysis to explore architecture in this multilayered context by considering the dynamics that lead to the visual experience. In particular, it is recommended that we assess the visualprocess of inhabitation, rather than assess the visibility in vacuo. In order to investigate the possibilities and limitations of the methodology, an urban environment is analysed by means of an agent-based model of visual actors within the configuration. The results obtained from the model are compared with actual pedestrian movement and other analytic measurements of the area: the agents correlate well both with human movement patterns and with configurational relationship as analysed by space-syntax methods. The application of both methods in combination improves on the correlation with observed movement of either, which in turn implies that an understanding of both the process of inhabitation and the principles of configuration may play a crucial role in determining the social usage of space

The role of angularity in route choice: an analysis of motorcycle courier GPS traces

The paths of 2425 individual motorcycle trips made in London were analyzed in order to uncover the route choice decisions made by drivers. The paths were derived from global positioning system (GPS) data collected by a courier company for each of their drivers, using algorithms developed for the purpose of this paper. Motorcycle couriers were chosen due to the fact that they both know streets very well and that they do not rely on the GPS to guide their navigation. Each trace was mapped to the underlying road network, and two competing hypotheses for route choice decisions were compared: (a) that riders attempt to minimize the Manhattan distance between locations and (b) that they attempt to minimize the angular distance. In each case, the distance actually traveled was compared to the minimum possible either block or angular distance through the road network. It is usually believed that drivers who know streets well will navigate trips that reduce Manhattan distance; however, here it is shown that angularity appears to play an important role in route choice. 63% of trips made took the minimum possible angular distance between origin and destination, while 51% of trips followed the minimum possible block distance. This implies that impact of turns on cognitive distance plays an important role in decision making, even when a driver has good knowledge of the spatial network

Hermeneutic resonance in animats and art

One major criticism of direct or active perception (and other forms of embodied action) from the perspective of cognitive psycology is that, according to common sense, there are some actions that require strictly symbolic information - for example, to stop a car in response to a red traffic light - which fall outside the realm of a perception-action cycle. Although such cognitive responses are not necessarily a goal of artificial life, they must necessarily be included within the embodied paradigm if it is to encompass the cognisant individual, the self-aware individual, or, potentially, the conscious individual. This paper will address the question, 'can an animat appreciate art?' Although this may seem very different to the example of a prosaic response to a traffic light, it will be argued that a common framework for establishing the meaning of an object is needed. It will also be argued that clarification to previous philosophical models of artistic engagement is required: in particular that the process of understanding is not a dialogue between an autopoietic artwork and animat, but that there is either a unity of object (artwork-animat) which becomes self-maintaining, or a more classical Gibsonian interpretation as a fixed set of affordances offered by an object to the subject, both of which lead to the conclusion that the process of understanding becomes a resonance in the unity or animat

The ingredients of an exosomatic cognitive map: isovists, agents and axial lines?

There is some evidence that an axial map, as used in space syntax, may be related to an underlying cognitive map in humans. However, the axial map is derived strictly from the mathematical configuration of space rather than any property of people. Hence there is a question of how a person might have embedded such a map. In this paper we report the results of several experiments which aim to improve the correlation between agent and pedestrian movement.We use a database of external occlusion points derived from isovists constructed throughout the system to provide a lookup table for agents to guide their movement. Since the table is external to the agents, we refer to the visual architecture as exosomatic. The results do improve on previous studies, but are still far from a good simulation of pedestrian movement. However, there is a philosophically important outcome from the experiments. When the agents are tuned to best performance, their movement patterns correspond to the axial structure of the system. This can be shown to be a mathematical result of their movement strategy; that is, the manifestation of movement, or the `memory' of an agent experiment, relates to the combination of the internal structure of the agent and its engagement with the environment in the form of an axial map. There are two unresolved steps from the relationship between individual and environment to human cognition: one, it cannot be shown that people do actually use occlusion points for movement, and two, even if they were to, it cannot be shown that they would use the resultant axial structure for higher level navigation decisions. Nevertheless, our results do provide evidence for a link between the individual and the axial map through embodiment of an agent-environment system, and our theory provides a mechanism for a link between the embodied map and preconditions for cognitive structure, which may in turn provide a basis for the future research into the means by which space syntax may be related to spatial cognition

A simple model of the Belousov-Zhabotinsky reaction from first principles

The Belousov-Zhabotinsky (BZ) reaction is an example of a temporally oscillating chemical reaction. An unusual and interesting feature of the reaction is that as it progresses on a twodimensional plate, self-organized spirals are formed. Many computer models have been constructed of the BZ reaction to simulate the evolution of these spirals. The models typically use cellular automata to allow progression of a wavefront through a notional substrate. Usually a single substrate is used with somewhat arbitrary transference rules. Here it is shown that cellular automata models of BZ spirals can be created by using a very simple set of equations based on a three substrate model with close connection to reaction-diffusion models, more closely resembling the actual BZ reaction. Source code for the model is given in the Processing language

From axial to road-centre lines: a new representation for space syntax and a new model of route choice for transport network analysis

Axial analysis is one of the fundamental components of space syntax. The space syntax community has suggested that it picks up qualities of configurational relationships between spaces not illuminated by other representations. However, critics have questioned the absolute necessity of axial lines to space syntax, as well as the exact definition of axial lines. Why not another representation? In particular, why not road-centre lines, which are easily available in many countries for use within geographical information systems? Here I propose that a recently introduced method of analysis, angular segment analysis, can marry axial and road-centre line representations, and in doing so reflect a cognitive model of how route choice decisions may be made. I show that angular segment analysis can be applied generally to road-centre line segments or axial segments, through a simple length- weighted normalisation procedure that makes values between the two maps comparable. I make comparative quantitative assessments for a real urban system, not just investigating angular analysis between axial and road-centre line networks, but also including more intuitive measures based on metric (or block) distances between locations. I show that the new angular segment analysis algorithm produces better correlation with observed vehicular flow than both standard axial analysis and metric distance measures. The results imply that there is no reason why space syntax inspired measures cannot be combined with transportation network analysis representations in order to create a new, cognitively coherent, model of movement in the city