Characterizing mixed-use buildings based on multi-source big data

To-date few research has successfully integrated big data from multiple sources to characterize urban mixed-use buildings. In this paper, we introduce a probabilistic model to integrate multi-source and geospatial big data (social network data, taxi trajectories, Points of Interest and remote sensing images) to characterize urban mixed-use buildings. The usefulness of our model is demonstrated with a case study of the Tianhe District in megacity Guangzhou, China. The model predicted building functions at 85% accuracy based on ground truth data from field surveys. We further explored the spatial patterns of the identified building functions. Most mixed-use buildings are located along major streets. Our proposed model can identify mixed-use buildings in a city; information is useful for planning evaluation and urban policymaking.     

基于街景数据的建成环境与街道活力时空分析——以深圳福田区为例

建成环境对街道活力的影响是国内外城市研究的热点议题。然而,对于建成环境要素的测度与评估多偏重于二维建成环境指标,尚未充分挖掘三维建成环境指标。以深圳市福田区为例,采用街景数据、路网数据、POI数据及移动互联网位置服务数据,建立周末分时段模型,探讨商业街道和生活街道活力的时空间分布特征及建成环境对其产生的影响。结果表明：① 商业街道上居民全天活动的峰值时段为18:00~20:00,生活街道上居民全天活动的峰值时段为11:00~13:00。② 深圳市福田区街道活力总体呈现多中心结构,随时间变化显现出明显的空间差异。③ 不同的建成环境指标对街道活力的作用时段与影响程度存在差异。提高功能混合度有利于提升商业街道凌晨、上午和夜间的活力及生活街道午后和傍晚的活力;过宽的相对步行宽度对生活街道活力提升有抑制作用,更安全的步行环境对商业和生活街道夜间活力提升有促进作用;界面连续程度高的商业街道午后及夜间的活力更强,界面多样性丰富的生活街道白天活力更强。     

Street networks in relation to landforms：Implications for fast-growing cities

In addition to socio-economic factors,major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful (a river) and Khorramabad (mountains and valleys),but no clear effects on the cities of Yazd and Nain. Also,where the street orientation is peaked,the Gibbs/Shannon entropy (a measure of dispersion or spread) is low,but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are,on average,shorter and denser (more streets per unit area) than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts,implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades,with the newer outer parts expanding rapidly. As shown here,the rapidly formed outer parts (with greater dispersion in street patterns) have significantly different textures from those of the older inner parts,indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide,particularly for analysing the effects of landforms on city shape and texture.     

与地形相关的街道网络分析及其对快速增长型城市的意义(英文)

In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful(a river) and Khorramabad(mountains and valleys), but no clear effects on the cities of Yazd and Nain. Also, where the street orientation is peaked, the Gibbs/Shannon entropy(a measure of dispersion or spread) is low, but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are, on average, shorter and denser(more streets per unit area) than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts, implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades, with the newer outer parts expanding rapidly. As shown here, the rapidly formed outer parts(with greater dispersion in street patterns) have significantly different textures from those of the older inner parts, indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide, particularly for analysing the effects of landforms on city shape and texture.     

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 set 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 the help of some graphic software has been a tedious manual process that is criticized for being time consuming, subjective, or even arbitrary. In this article, we redefine axial lines as the least set 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 for 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 for capturing the underlying urban structure.     

Street networks in relation to landforms: Implications for fast-growing cities简

In addition to socio-economic factors, major landforms may affect the city structure and urban form. Here we show that landforms have significant effects on the city shape and street patterns of the fast-growing Iranian cities of Dezful （a river） and Khorramabad （moun- tains and valleys）, but no clear effects on the cities of Yazd and Nain. Also, where the street orientation is peaked, the Gibbs/Shannon entropy （a measure of dispersion or spread） is low, but increases as the distribution becomes more uniform because of landform constraints. The streets in the old inner parts of all the cities are, on average, shorter and denser （more streets per unit area） than the streets of the newer outer parts. The entropies of the outer parts are also greater than those of the inner parts, implying that the street-length distribution gradually becomes more dispersed or spread as the city expands. All these cities have been fast growing in the past decades, with the newer outer parts expanding rapidly. As shown here, the rapidly formed outer parts （with greater dispersion in street patterns） have significantly different textures from those of the older inner parts, indicating different functionality and growth processes. These quantitative methods for street-network analysis can be used worldwide, particularly for analysing the effects of landforms on city shape and texture.     

基于街景影像和手机信令数据的城市街道安全性研究

城市化进程加快导致街道安全性问题突出,已有研究利用城市视觉要素刻画街道安全感空间分布,忽略了街道真实安全性与安全感间的差异。该文利用街景影像和手机信令数据,结合K-means聚类算法与笛卡尔积运算模型减少“安全感知差异”,以长沙市主城区为研究案例,得到白天、夜晚及总体城市街道安全性分布:1)长沙市主城区安全感指数随圈层数增加呈波动递减趋势,主要原因是建筑视觉要素占比下降较快以及天空视觉要素占比逐步上升;2)长沙市主城区呈双圈层结构,白天高安全性、夜晚低安全性以及总体安全性最低的区域主要分布在主城区中心,具有明显的聚集现象。该研究通过对城市街道安全性和低安全性街道的分析提出街道优化建议,为城市规划提供参考。     

大连城市绿地可达性对房价影响的差异性分析

研究房价、遥感影像等多源数据,采用邻域分析法和地理加权回归模型分析大连市中山区绿地可达性及其与房价之间的空间相关性。结果表明：① 房价均价14 745.35元/m²,呈环状分布,由沿海向内陆衰减、桂林街道起中心向外围递减;② 研究区内可达性最好的绿地类型是街旁绿地,绿地可达性总体水平最高街道是桂林街道;公园绿地可达性最好的住宅区分布在昆明街道和桃源街道,街旁绿地可达性最好的住宅区分布在桂林街道,附属绿地可达性最好的分布在老虎滩街道,其他绿地可达性最好的分布在桃源街道。③ 不同类型绿地可达性对房价影响作用程度递减排序为：附属绿地、街旁绿地、公园绿地和其他绿地;附属绿地、街旁绿地和其他绿地与房价呈现空间正相关,随着到达绿地距离降低,房价呈现增长趋势;公园绿地与房价呈现负相关,随着到达公园绿地的距离降低,房价呈现衰减趋势。     

STREET BARRIERS IN AMERICAN CITIES

The paper examines the emergence of urban street barriers, which are objects placed by municipal governments or neighborhood associations on publicly owned, local service streets to control vehicular traffic. An increasing number of U.S. cities have adopted street barriers in order to deter crime and to regulate commuter traffic. The paper discusses the conditions that prompted cities to adopt street barriers and the results of their installations. Street barriers are effective as traffic controls but have mixed results in reducing crime. The philosophical issues relating to the continued adoption of street barriers are addressed. The paper concludes with a call for additional research on street barriers.     

杭州商业街道空间布局形态关键要素对周边风环境的影响

利用基于计算流体力学（CFD）理论的数值模拟软件,在不影响街道连续性面貌的前提下,通过控制变量法分别改变街道贴线率、街道界面密度、街道高宽比3个关键要素的数值来观察街道风环境的变化情况。结论主要有： 街道内的风速大小随着街道贴线率的增大呈抛物线趋势变化,先增大后减小,在街道贴线率接近70%时,城市街道内风速达到最大; 随着界面密度的不断减小,城市街道内各个测点的风速变化的幅度越来越大,这样会让在其中行走的行人感受到强烈的风速变化,舒适度大为下降; 城市街道内的平均风速和街道高宽比成反比例关系。     

The impact of planning on pedestrian movement: contrasting pedestrian movement models in pre-modern and modern neighborhoods in Israel

Most pedestrian movement volume models were constructed for urban areas that developed on the basis of pre-modern planning. In this paper, we confront neighborhoods that were built upon modern planning doctrines, combining the functional hierarchy of streets with the neighborhood unit concept, with neighborhoods that developed from pre-modem non-hierarchical street-based planning. We use space syntax analysis to investigate how their street network’s structural attributes interact with pedestrian movement distribution. The investigation was conducted in 14 neighborhoods from 4 cities in Israel by examining the correlation of observed pedestrian volume with models using different axial- and segment-based topological, angular, and metric syntactic attributes across different radii (scales). The results indicate that the street network and the distribution of pedestrian movement interact differently in the two neighborhood types. In pre-modern neighborhoods: (i) there is significantly more walking; (ii) the street network’s syntactic attributes tend to be much more consistent in their correlation with pedestrian volume across all scales; (iii) the correlation of pedestrian volume with these attributes and with commerce is relatively high; and (iv) pedestrian movement distribution is more predictable. We relate these differences to the absence of a self-organized circular causality between street network structure, commerce, and movement in modern planned neighborhoods.     

集成不同类型特征的城市道路选取方法研究

道路选取是进行道路网地图综合及多尺度表达时的基础。现有的道路选取方法大多是以道路的语义特征和几何特征作为道路选取的依据,较少考虑道路的拓扑特征。基于此,该文以城市道路网为例,综合考虑道路的语义特征、几何特征和拓扑特征,并以道路综合性能作为城市道路选取的依据,提出一种城市道路选取的新方法。通过实例分析,验证了该方法的有效性。     

城镇增长下的收缩：以武汉为例

首先从人口、经济、用地3个维度综合考察武汉市增长与收缩的全貌,并采用县区及街道2个尺度的数据定量描述了武汉市增长与收缩的特征与空间格局,发现武汉市下辖青山区、硚口区、汉阳区和蔡甸区存在局部较严重的收缩现象,空间上形成集聚,形态上呈“穿孔式”。进一步以青山区为案例,着重从资本视角探讨发生局部收缩的内在机制,发现其存在老龄化、少子化趋势,但局部收缩的主因是资本从产业部门的“逃逸”。     

Minimum geocoding match rates: an international study of the impact of data and areal unit sizes

ABSTRACT

The analysis of geographically referenced data, specifically point data, is predicated on the accurate geocoding of those data. Geocoding refers to the process in which geographically referenced data (addresses, for example) are placed on a map. This process may lead to issues with positional accuracy or the inability to geocode an address. In this paper, we conduct an international investigation into the impact of the (in)ability to geocode an address on the resulting spatial pattern. We use a variety of point data sets of crime events (varying numbers of events and types of crime), a variety of areal units of analysis (varying the number and size of areal units), from a variety of countries (varying underlying administrative systems), and a locally-based spatial point pattern test to find the levels of geocoding match rates to maintain the spatial patterns of the original data when addresses are missing at random. We find that the level of geocoding success depends on the number of points and the number of areal units under analysis, but generally show that the necessary levels of geocoding success are lower than found in previous research. This finding is consistent across different national contexts.     

人口统计数据的空间转换

在经济和社会研究中,所要研究的区域之上经常没有数据,而这些数据需要由已知区域的数据求得,即统计数据需要空间转换,这就通常涉及到面积内插。本文从GIS的角度研究如何解决人口内插问题,认为面积内插和GIS中的叠加分析是一致的。在传统的面积内插方法的基础上是提出了基于人口真实分布的面积内插方法,并推导出了公式。同时提出了人口密度的递归算法,即把居住区分为人口稀疏地区和人口稠密地区,估计出人口稀疏地区的人口密度,就可以求出人口密集地区的人口密度;再把人口密集区分为新的人口稀疏区和密集区,此过程反复直至求出接近于人口真实分布的人口模型。     

Geographic space as a living structure for predicting human activities using big data

Inspired by Christopher Alexander’s conception of the world – space is not lifeless or neutral, but a living structure involving far more small things than large ones – a topological representation has been previously developed to characterize the living structure or the wholeness of geographic space. This paper further develops the topological representation and living structure for predicting human activities in geographic space. Based on millions of street nodes of the United Kingdom extracted from OpenStreetMap, we established living structures at different levels of scale in a nested manner. We found that tweet locations at different levels of scale, such as country and city, can be well predicted by the underlying living structure. The high predictability demonstrates that the living structure and the topological representation are efficient and effective for better understanding geographic forms. Based on this major finding, we argue that the topological representation is a truly multiscale representation, and point out that existing geographic representations are essentially single scale, so they bear many scale problems such as modifiable areal unit problem, the conundrum of length and the ecological fallacy. We further discuss on why the living structure is an efficient and effective instrument for structuring geospatial big data, and why Alexander’s organic worldview constitutes the third view of space.     

Spatial order through the family: the regulation of urban space in Singapore

This article examines the regulation of urban public space through a study of the role of the family unit in past and present urban development in Singapore. Since the founding of modern Singapore 50 years ago, the nuclear family has remained the preferred social institution for state policies and subsequent regulation of education, housing, employment, health, leisure, social welfare and even neighborhood development. Drawing on primary government documents and field work and interviews with current and displaced small business owners on a commercial street in Chinatown, the article demonstrates how a “softer” version of spatial regulation emerged from an intersection of state commercial development policies that favored small, family-owned businesses and the extension of a family-based moral social order applied to the surrounding public spaces. The result is the regulation of Chinatown’s streets and sidewalks became inextricably bound up with the everyday operations of family-run businesses. More recently, state interest in creating an entertainment-based global Singapore has jeopardized this arrangement, as corporate gentrification threatens to displace family ownership of small businesses.     

北京城市产业碳排放的小尺度空间分布

基于城市乡镇街道空间单元及能源消费碳排放的定量方法基础上,计算了北京市2004和2008 年第二、三产业的二氧化碳排放量及其空间分布。结果表明：北京市第二产业的碳排放总量变化不大,空间上呈现东南高、西北低的格局;第三产业的碳排放总量则有明显的增长,空间上呈现内城区碳排放值较高、且向外围圈层扩散的趋势;第三产业中分配性服务业和生产性服务业的碳排放量较高,2008 年分配性服务业碳排放的高值区主要分布于南部的城市近郊区,生产性服务业碳排放的高值区分布于高端服务业较为集聚的区域。