Automatic Generation of the Axial Lines of Urban Environments to Capture What We Perceive

Based on the concepts of isovists and medial axes, we developed a set of algorithms that can automatically generate axial lines for representing individual linearly stretched parts of open space of an urban environment. Open space is the space between buildings, where people can freely move around. The generation of the axial lines has been a key aspect of space syntax research, conventionally relying on hand-drawn axial lines of an urban environment, often called axial map, for urban morphological analysis. Although various attempts have been made towards an automatic solution, few of them can produce the axial map that consists of the least number of longest visibility lines, and none of them really works for different urban environments. Our algorithms provide a better solution than existing ones. Throughout this paper, we have also argued and demonstrated that the axial lines constitute a true skeleton, superior to medial axes, in capturing what we perceive about the urban environment. Keywords: Visibility, space syntax, topological analysis, medial axes, axial lines, isovistsComment: 13 pages, 9 figures submitted to International Journal of Geographical Information Science. With version 2, the concept of bucket has been explained and illustrated in more detail. With version 3, better formating and finetun

Defining and Generating Axial Lines from Street Center Lines for better Understanding of Urban Morphologies

Axial lines are defined as the longest visibility lines for representing individual linear spaces in urban environments. The least number of axial lines that cover the free space of an urban environment or the space between buildings constitute what is often called an axial map. This is a fundamental tool in space syntax, a theory developed by Bill Hillier and his colleagues for characterizing the underlying urban morphologies. For a long time, generating axial lines with help of some graphic software has been a tedious manual process that is criticized for being time consuming, subjective, or even arbitrary. In this paper, we redefine axial lines as the least number of individual straight line segments mutually intersected along natural streets that are generated from street center lines using the Gestalt principle of good continuity. Based on this new definition, we develop an automatic solution to generating the newly defined axial lines from street center lines. We apply this solution to six typical street networks (three from North America and three from Europe), and generate a new set of axial lines for analyzing the urban morphologies. Through a comparison study between the new axial lines and the conventional or old axial lines, and between the new axial lines and natural streets, we demonstrate with empirical evidence that the newly defined axial lines are a better alternative in capturing the underlying urban structure. Keywords: Space syntax, street networks, topological analysis, traffic, head/tail division ruleComment: 10 pages, 7 figures, and 2 tables, one figure added + minor revisio

ANALYSIS OF SPACE, COGNITION AND PEDESTRIAN MOVEMENT

Understanding the movement of people in urban areas is one of the most significant issues on spatial science with a wide range of applications in urban design, public health, public safety and intelligent transportation system. Urban planners, cognitive scientists, computer engineers, and geographers have contributed to an understanding of pedestrian movement from aspects of configurational analysis, knowledge representation, computational models, and space-time patterns respectively. However, no previous studies provide comprehensive solutions to pedestrian movement taking both space and cognition into account. Combining these disciplines allows us as researchers to not only explain correlations between spatial layouts and pedestrian flows but also understand how and why environmental perception and spatial knowledge are used by pedestrians to orient themselves and navigate through space. My research proposes a theoretical framework of space, cognition and movement to fill in interdisciplinary gaps of pedestrian movement studies. The core of this framework lies in the hypothesis that where people choose to hold activities and how people choose to get there depends on individuals’ cognitive maps of the environment. This cognitive map consists of the salient layout of spatial features as well as the prominent utilities afforded by these features. The analysis proceeds from three dimensions: (1) space syntax to characterize spatial configuration or structure, (2) space semantics to address the distribution of activities, and (3) spatial cognition to capture one’s knowledge about the space. The proposed framework was used to guide an empirical study conducted at the University of Oklahoma Norman Campus. Space was characterized by two aspects of space syntax and space semantics. For syntactical analysis, the study not only used measures of network centrality to examine network effects on pedestrian movement but also improved them by varying concepts of distance, adding distance decay effects, and weighting spatial heterogeneity of activities. Betweenness centrality calculated by the shortest length and weighted by distance decay effects resulted in the best description of observed pedestrian flows. In semantical analysis, functional centrality was described by density and diversity. Only functional density significantly contributed to modeling pedestrian flows. This study provided evidence that pedestrian movement depended on the spatio-functional interactions. The distribution of activities not only took the location advantage provided by spatial configuration but also reinforced network effects on pedestrian movement. This study not only examined aggregated patterns of pedestrian movement but also investigated individual variations in cognitive maps and wayfinding behaviors. The sketch map analysis suggested that as people became more familiar with the environment, the increase of completeness and accuracy was observed in their cognitive maps. Completeness was described by number of landmarks in sketch maps while accuracy concentrated on the relative positions between pairs of landmarks. Landmark served as the organizing concept of cognitive map. Betweenness centrality, functional density, and familiarity significantly contributed to modeling the presence of landmarks. When landmarks were used in navigation, this study developed a landmark-based pathfinding method. Landmark-based pathfinding resulted in a better description of routes selected by survey participants. In sum, individual cognitive maps, particularly the organization of landmarks, serve as the core in determining where pedestrians choose to hold activities and how to get there. Finally, the study developed the conceptual agent-based model (ABM) for pedestrian movement. The core of this ABM lies in a cognizing agent that is able to solve pathfinding tasks based on perceptual information and knowledge of cognitive map. The research outcomes not only improve the understanding of spatial and cognitive factors on pedestrian wayfinding but also contribute to several disciplines. Architects and urban planners can adopt the framework of pedestrian movement to test, assess and improve existing spatial layouts and possible design alternatives. Computer scientists and Geographic Information System developers can use the specification of cognitive map to implement landmark based navigation system. Cognitive scientists and psychologists can apply the comprehensive model of pedestrian movement in research on human wayfinding behaviors for people with different perceptual abilities

Artificial intelligence and architectural design : an introduction

Descripció del recurs: 27 juliol 2022The aim of this book on artificial intelligence for architects and designers is to guide future designers, in general, and architects, in particular, to support the social and cultural wellbeing of the humanity in a digital and global environment. This objective is today essential but also extremely large, interdisciplinary and interartistic, so we have done just a brief introduction of the subject. We will start with the argument fixed by the Professor Jonas Langer in his web some years ago, that we have defined as: “The Langer’s Tree”.Primera edició

Walking in the cities without ground, how 3D complex network volumetrics improve analysis

Pedestrian route choice, wayfinding behaviour and movement pattern research rely on objective spatial configuration model and analysis. In 3D indoor and outdoor multi-level buildings and urban built environments (IO-ML-BE), spatial configuration analysis allows to quantify and control for route choice and wayfinding complexity/difficulty. Our contribution is to compare the interaction of the level of definition (LOD) of indoor and outdoor multi-level pedestrian network spatial models and complexity metric analyses. Most studies are indoor or outdoor and oversimplify multi-level vertical connections. Using a novel open data set of a large-scale 3D centreline pedestrian network which implement transport geography 2D data model principles in 3D, nine spatial models and twelve spatial complexity analyses of a large-scale 3D IO-ML-BE are empirically tested with observed pedestrian movement patterns (N = 17,307). Bivariate regression analyses show that the association with movement pattern increases steadily from R2 ≈ 0.29 to 0.56 (space syntax, 2.5D) and from R2 ≈ 0.54 to 0.72 (3D sDNA) as the 3D transport geography spatial model LOD and completeness increases. A multivariate stepwise regression analysis tests the bi-variate findings. A novel 3D hybrid angular-Euclidean analysis was tested for the objective description of 3D multi-level IO-ML-BE route choice and wayfinding complexity. The results suggest that pedestrian route choice, wayfinding and movement pattern analysis and prediction research in a multi-level IO-ML-BE should use high-definition 3D transport geography network spatial model and include interdependent outdoor and indoor spaces with detailed vertical transitions

Urban function connectivity: Characterisation of functional urban streets with social media check-in data

Social media check-in data, one type of crowdsourcing open data about individual activity-related choices, provides a new perspective to sense people's spatial and temporal preference in urban places. In this paper, through the analysis of the interaction between these scored places on streets, we aim to advance our knowledge of network accessibility with social media check-ins to portray urban structure and related socioeconomic performance more explicitly. By conceptualising an interface graph to reflect the interplay between land-use points and the co-visual paths, we propose a novel framework to characterise the urban streets with land-use connectivity indices that are measured with a new type of place-function signature. A “3-Ds” model is introduced to package three principal dimensions of urban function network, including accessible density, accessible diversity and delivery efficiency, as one integrated index that works towards a comprehensive understanding of function connectivity from each street's midpoints to all reachable land-use points. Streets are further partitioned to the annotated function regions based on function connectivity in different types of active land-use. The results of preliminary studies in the city of Tianjin, China show that the proposed metrics can explicitly describe the inherent function structure and the regions' typology across scales. Compared with space syntax measurements at the same radius for describing the variation of empirically observed house price, the integrated metric can improve the predictability of statistic models sufficiently, and each specified index is confirmed to be statistically significant by controlling other factors. Overall, this research shows that the usage of ubiquitous big social media data can enrich the current description of the urban network system and enhance the predictability of network accessibility on socioeconomic performance