The shift from Axial to Line-segment maps is one of the most important developments in Space Syntax analysis, both theoretically and methodologically. It followed a long line of investigations and discussions within the field of Space Syntax, which addressed critical issues related to the Axial map representation (e.g. Hillier and Iida,2005; Hillier,1999a,1999b; Turner,2001; Steadman,2004, Dalton, 2001). At the same time, it opened up new possibilities by allowing for the use of Road-centre-line maps in Space Syntax analysis; that is, largely available GIS-based segment maps, used in most areas of urban modelling (e.g. Turner,2007; Dalton et al.,2003). Today, several models implement syntactical analysis to Road-centre-line maps, while claiming to form valid alternatives to the Axial map, not least in capturing the perceptual and cognitive affordances presented by the environment.
This paper focuses on such alternative models with a twofold aim: first, to help make well-grounded choices in applying syntactical analysis to Road-centre-line maps; and second, to explore the methodological potentials of Line-segment maps, which are created by their flexibility, by being the least aggregated representations of street networks. The paper introduces an experimental software application to push the investigations and exploit these methodological possibilities even further.
The models discussed in this paper are: 1) Angular Segment Analysis (e.g. Turner,2007; Hillier and Iida,2005); 2) Natural Streets maps (Jiang and Liu,2007) and Continuity maps (Figueiredo and Amorim,2005); 3) Directional Distance model (Peponis et al.,2008). Based on a systematic comparison of: a) their geometric representation of the street network (the ‘map’), b) the dual- graph they calculate, and c) the measure of distance they use, we argue that they can all be seen as parametrically defined representations, based on a Line-segment map. In other words, with the same Line-segment map one could produce all of them, if a different set of angular parameters was used, to either define the graph elements (nodes, edges), or to calculate distance. These models, parametrically redefine the relation between the ‘map’ and the ‘graph’; thus, challenging the one-to-one relation between the two, that the Axial map was founded upon.
The methodological importance of this development goes beyond the specific models described in this paper. If the same Line-segment map can produce different graphs by using a different set of angular parameters, then, for instance, one could easily change the parameters to follow the latest theoretical insights on human cognition, without having to change the map. Going even further, one could develop and test different representational models to explore new theoretical and methodological paths, by using one single map. The experimental tool also presented in this paper is a step in that direction, allowing to test different models using a single software.
[1]
Bin Jiang,et al.
Integration of Space Syntax into GIS: New Perspectives for Urban Morphology
,
2002,
Trans. GIS.
[2]
L. Marcus.
Ecological space and cognitive geometry: Linking humans and environment in space syntax theory
,
2015
.
[3]
E. Reed.
The Ecological Approach to Visual Perception
,
1989
.
[4]
V. Cutini.
Axial lines and contour lines: climbing up the centre
,
2007
.
[5]
Michael Batty,et al.
Complex spatial systems: The modelling foundations of urban and regional analysis
,
2001
.
[6]
J. Gibson.
The Ecological Approach to Visual Perception
,
1979
.
[7]
C. Ratti.
Space Syntax: Some Inconsistencies
,
2004
.
[8]
Alasdair Turner,et al.
An Algorithmic Definition of the Axial Map
,
2005
.
[9]
John Peponis,et al.
To tame a TIGER one has to know its nature:extending weighted angular integration analysis to the descriptionof GIS road-centerline data for large scale urban analysis
,
2003
.
[10]
R. Dalton.
The Secret Is To Follow Your Nose
,
2001
.
[11]
Claire Ellul,et al.
From the axial line to the walked line: Evaluating the utility of commercial and user-generated street network datasets in space syntax analysis
,
2012
.
[12]
Philip Steadman,et al.
Developments in Space Syntax
,
2004
.
[13]
Bill Hillier,et al.
The Hidden Geometry of Deformed Grids: Or, Why Space Syntax Works, When it Looks as Though it Shouldn't
,
1999
.
[14]
John Peponis,et al.
The Connectivity of Streets: Reach and Directional Distance
,
2008
.
[15]
B. Hillier,et al.
Rejoinder to Carlo Ratti
,
2004
.
[16]
Bill Hillier,et al.
Network effects and psychological effects: a theory of urban movement
,
2005
.
[17]
Lucas Figueiredo,et al.
Continuity lines in the axial system
,
2005
.
[18]
A Turner.
Could a road-centre line be an axial line in disguise?
,
2005
.
[19]
Alan Wilson,et al.
Complex Spatial Systems: The Modelling Foundations of Urban and Regional Analysis
,
2016
.
[20]
R. Thomson,et al.
Smoothly continuous road centre-line segments as a basis for road network analysis
,
2003
.
[21]
Bill Hillier,et al.
Centrality as a process: accounting for attraction inequalities in deformed grids
,
1999
.
[22]
M. Batty.
The New Science of Cities
,
2013
.
[23]
B. Hillier,et al.
The Social Logic of Space
,
1984
.
[24]
Nick Dalton,et al.
Fractional Configurational Analysis And a solution to the Manhattan problem
,
2001
.
[25]
Alasdair Turner,et al.
From Axial to Road-Centre Lines: A New Representation for Space Syntax and a New Model of Route Choice for Transport Network Analysis
,
2007
.
[26]
Bin Jiang,et al.
Street‐based topological representations and analyses for predicting traffic flow in GIS
,
2007,
Int. J. Geogr. Inf. Sci..
[27]
Christophe Claramunt,et al.
Topological Analysis of Urban Street Networks
,
2004
.