The theory of affordances

Transactions of the Institute of British Geographers

The first Danish language version of this book, published in 1971, was very much a protest against the functionalistic principles for planning cities and residential areas that prevailed during that period. The book carried an appeal to show concern for the people who were to move about between buildings, and it urged an understanding of the subtle, almost indefinable - but definite - qualities, which have always related to the interaction of people in public spaces, and it pointed to the life between buildings as a dimension of architecture that needs to be carefully treated. Now 40 years later, many architectural trends and ideologies have passed by over the years. These intervening years have also shown that the liveliness and liveability of cities and residential areas continues to be a important issue. The intensity in which fine public spaces are used at this point in time, as well as the greatly increased general interest in the quality of cities and their public spaces emphasises this point. The character of life between buildings changes with changes in any given social context, but the essential principles and quality criteria to be employed when working with life between buildings has proven to be remarkably constant. Though this work over the years has been updated and revised several times, this version bears little resemblance with the very early versions, however there was no reason to change the basic message: Take good care of the life between your buildings.

Life between buildings: Using public space

Object tracking typically relies on a dynamic model to predict the object's location from its past trajectory. In crowded scenarios a strong dynamic model is particularly important, because more accurate predictions allow for smaller search regions, which greatly simplifies data association. Traditional dynamic models predict the location for each target solely based on its own history, without taking into account the remaining scene objects. Collisions are resolved only when they happen. Such an approach ignores important aspects of human behavior: people are driven by their future destination, take into account their environment, anticipate collisions, and adjust their trajectories at an early stage in order to avoid them. In this work, we introduce a model of dynamic social behavior, inspired by models developed for crowd simulation. The model is trained with videos recorded from birds-eye view at busy locations, and applied as a motion model for multi-people tracking from a vehicle-mounted camera. Experiments on real sequences show that accounting for social interactions and scene knowledge improves tracking performance, especially during occlusions.

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You'll never walk alone: Modeling social behavior for multi-target tracking

Existing theories relating patterns of pedestrian and vehicular movement to urban form characterise the problem in terms of flows to and from 'attractor' land uses. This paper contains evidence in support of a new 'configurational' paradigm in which a primary property of the form of the urban grid is to privilege certain spaces over others for through movement In this way it is suggested that the configuration of the urban grid itself is the main generator of patterns of movement. Retail land uses are then located to take advantage of the opportunities offered by the passing trade and may well act as multipliers on the basic pattern of 'natural movement' generated by the grid configuration. The configurational correlates of movement patterns are found to be measures of global properties of the grid with the 'space syntax' measure of 'integration' consistently found to be the most important. This has clear implications for urban design suggesting that if we wish to design for well used urban space, then it is not the local properties of a space that are important in the main but its configurational relations to the larger urban system.

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Natural Movement: Or, Configuration and Attraction in Urban Pedestrian Movement:

An isovist, or viewshed, is the area in a spatial environment directly visible from a location within the space. Here we show how a set of isovists can be used to generate a graph of mutual visibility between locations. We demonstrate that this graph can also be constructed without reference to isovists and that we are in fact invoking the more general concept of a visibility graph. Using the visibility graph, we can extend both isovist and current graph-based analyses of architectural space to form a new methodology for the investigation of configurational relationships. The measurement of local and global characteristics of the graph, for each vertex or for the system as a whole, is of interest from an architectural perspective, allowing us to describe a configuration with reference to accessibility and visibility, to compare from location to location within a system, and to compare systems with different geometries. Finally we show that visibility graph properties may be closely related to manifestations of spatial perception, such as way-finding, movement, and space use.

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From Isovists to Visibility Graphs: A Methodology for the Analysis of Architectural Space

Transportation research has usually seen road networks as inert systems to be navigated and eventually filled up by traffic. A new type of ‘configurational’ road network modelling, coupled to detailed studies of vehicular and pedestrian flows, has shown that road networks have a much more constructive role. They strongly influence the pattern of flows through quantifiable properties of the network ‘configuration’. Recent research results are presented showing that rates of vehicular movement in road segments are to a greater extent than previously realised the direct outcome of the location of those segments in the network configuration as a whole and that this is the case especially in the fine structure of the urban grid. A supply and demand model of urban movement is proposed in which the degree to which a street alignment is on simplest routes between all other pairs of alignments in the system determines the demand side of the equation, and the effective road width available to traffic determines the...

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Configurational Modelling of Urban Movement Networks

Gibson's ecological theory of perception has received considerable attention within psychol- ogy literature, as well as in computer vision and robotics. However, few have applied Gibson's approach to agent-based models of human movement, because the ecological theory requires that individuals have a vision-based mental model of the world, and for large numbers of agents this becomes extremely expensive computationally. Thus, within current pedestrian models, path evalua- tion is based on calibration from observed data or on sophisticated but deterministic route-choice mechanisms; there is little open-ended behavioural modelling of human-movement patterns. One solution which allows individuals rapid concurrent access to the visual information within an envi- ronment is an 'exosomatic visual architecture', where the connections between mutually visible locations within a configuration are prestored in a lookup table. Here we demonstrate that, with the aid of an exosomatic visual architecture, it is possible to develop behavioural models in which movement rules originating from Gibson's principle of affordance are utilised. We apply large numbers of agents programmed with these rules to a built-environment example and show that, by varying parameters such as destination selection, field of view, and steps taken between decision points, it is possible to generate aggregate movement levels very similar to those found in an actual building context.

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Encoding Natural Movement as an Agent-Based System: An Investigation into Human Pedestrian Behaviour in the Built Environment

Space syntax research has found that spatial configuration alone explains a substantial proportion of the variance between aggregate human movement rates in different locations in both urban and bu...

Alan Penn

Papers

Natural Movement: Or, Configuration and Attraction in Urban Pedestrian Movement:

From Isovists to Visibility Graphs: A Methodology for the Analysis of Architectural Space

Configurational Modelling of Urban Movement Networks

Encoding Natural Movement as an Agent-Based System: An Investigation into Human Pedestrian Behaviour in the Built Environment

Space Syntax And Spatial Cognition Or Why the Axial Line