Integrating multi-source big data to infer building functions

Information about the functions of urban buildings is helpful not only for developing a better understanding of how cities work, but also for establishing a basis for policy makers to evaluate and improve the effectiveness of urban planning. Despite these advantages, however, and perhaps simply due to a lack of available data, few academic studies to date have succeeded in integrating multi-source ‘big data’ to examine urban land use at the building level. Responding to this deficiency, this study integrated multi-source big data (WeChat users’ real-time location records, taxi GPS trajectories data, Points of Interest (POI) data, and building footprint data from high-resolution Quickbird images), and applied the proposed density-based method to infer the functions of urban buildings in Tianhe District, Guangzhou, China. The results of the study conformed to an overall detection rate of 72.22%. When results were verified against ground-truth investigation data, the accuracy rate remained above 65%. Two important conclusions can be drawn from our analysis: 1.The use of WeChat data delivers better inference results than those obtained using taxi data when used to identify residential buildings, offices, and urban villages. Conversely, shopping centers, hotels, and hospitals, were more easily identified using taxi data. 2. The use of integrated multi-source big data is more effective than single-source big data in revealing the relation between human dynamics and urban complexes at the building scale.     

城市热岛效应对天津市居住建筑供暖和制冷负荷的影响

城市热岛效应已对建筑能源需求产生了重要影响,评估城市热岛效应影响下建筑的真实能耗需求及城乡差异对既有建筑的节能调控和未来建筑的方案设计都具有重要意义。论文以天津自动气象站2009—2017年逐时观测数据为基础,应用卫星遥感选站方法,选取天津市区周围4个有代表性的乡村参考气象站,对典型居住建筑全年逐时负荷进行了动态模拟,定量评估了城市热岛强度对不同时间尺度(年、日和小时)建筑负荷的影响。结果表明：① 随着城市热岛强度(I_UHI)的增强,城市居住建筑供暖负荷减少、制冷负荷增加,且年平均供暖负荷的减小幅度大于年平均制冷负荷的增加幅度。I_UHI每上升1 ℃,城市年平均供暖负荷较乡村减少4.01 kWh/m²、年平均制冷负荷增加1.05 kWh/m²。② 冬季供暖期和夏季制冷期逐日负荷变化表现为：供暖期的高负荷时段主要集中在12月下旬至翌年1月下旬、制冷期为7月下旬至8月上旬,高负荷时段城市日平均供暖和制冷负荷分别较乡村约减少10%、增加6%。③ 日内供暖负荷和制冷负荷小时变化均表现为夜间强于白天。在供暖期和制冷期,北京时间18:00至次日07:00时段无论在城市或是乡村都是高负荷时段;11:00至15:00时段在供暖期是低负荷时段,而在制冷期是高负荷时段,这可能与气温和供暖制冷需求有关。研究表明,应充分考虑小时、日尺度热岛强度对用能的影响,提高供暖和空调运行调控的精细化水平,以期达到降低供暖和制冷能耗的目的。     

Living the good life? The rise of urban mixed-use enclaves in Metro Manila

Gated communities and other forms of privatized enclaves have become features of many cities. The rise of urban mixed-use enclaves, which integrate functions of work, entertainment and living, is a relatively new and understudied phenomenon that is expanding rapidly throughout the Global South. In this article, we advance the concept of enclave urbanism through a case study of Eastwood City in Metro Manila, the Philippines. We trace the enabling factors for mixed-use enclave creation and assess how the different functions are marketed and integrated in practice into one “live–work–play” development. Based on extensive qualitative research, we argue that the global capital accumulation strategy of real estate developers leads to a strong focus on production and entertainment functions, but neglects questions of liveability. We reflect on the implications of our findings for mega-urban regions and urban studies research.     

上海城市天际线与高层建筑发展之关系分析

以上海市2000年中心城区航空影像为基础,基于GIS技术分析城市高层建筑与天际线的分布特点及其影响机制。认为城市天际线与高层建筑相互制约,高层建筑的发展与布局必须考虑城市天际线的特色。     

大连市中山区城市建筑垂直特征对城市热环境效应的影响

以大连市中山区的遥感和建筑数据为基础,利用单窗算法和相关分析方法,研究2007年、2017年研究区的地表温度空间分异特征,以及地表温度与建筑高度的相关性。研究结果表明： 2007年、2017年研究区最低温度由22.497℃增长到29.015℃,最高温度由36.091℃增长到43.213℃。研究区北部、解放路和中南路沿线、青泥洼-天津街商贸集聚区附近温度明显增高。 2007年、2017年,研究区区域内建筑都有所增高,中山区北部和青泥洼-天津街商贸集聚区附近建筑明显增高,研究区建筑有向南蔓延的趋势。 2007年、2017年,地表温度与建筑高度呈现低相关性,相关系数分别为0.346、0.331。     

广州主城区建筑组合的类型、空间分布与影响因素

基于2017年广州市单体建筑数据,以建筑高度和建筑间距2个指标,确定主城区基本的建筑组合,利用热点分析辨识更高尺度上的建筑组合,在此基础上分析广州建筑组合的空间分布及其影响因素。主要结论有：1）建筑组合有9种基本类型,4 272斑块数量与面积在占比上具有很强的同步性。2）百米尺度斑块构成了主城区建筑组合的基本单元,并以混合用地类型为主,由高层建筑组成的类型用地功能指示作用明显。3）主城区基本类型圈层分布特点突出,各类型圈层分异规律存在差异。4）地价是城市建筑高度、人口密度由中心向外递减的核心制约因子,是城市建筑组合分异的宏观背景因素,并能在平原地形上很好地以圈层形式呈现出来。在百米尺度上,绿地、珠江与主干道在微观层面对建筑组合类型、高度和密度产生影响,使得主城区建筑组合复杂化、多样化。     

三维虚拟城市自动化生成方法研究

从城市元胞自动机模型的角度研究三维虚拟城市的自动化生成方法.通过建立城市元胞自动机模型,模拟城市土地单元的演化过程,根据演化结果确定各土地单元的空间位置和相应的建筑物类型.研究利用Creator进行三维场景建模,利用OpenGVS场景管理技术随机生成建筑物,并将其布设在三维场景的相应位置上,生成三维虚拟城市,并就三维虚拟城市自动化生成系统的功能结构设计和数据结构、空间坐标转换等技术问题进行了探讨.     

城市建筑空间设计的犯罪防控效应

建筑空间设计包括外部空间设计与内部空间设计,前者设计建筑物之间的空间组合形态,后者设计建筑内部的空间组合形态。合理的建筑物空间设计是创造可防控空间的有效手段,是消除建筑空间盲区的有力措施,也是实施城市犯罪空间防控的重要途径。建筑外部空间组合设计发挥防控效应有两个工作层面,一是将建筑单体组合成群体,二是将建筑群体组合成组团。建筑内部空间组合设计发挥防控效应包括住宅建筑内部空间设计、公共设施建筑内部空间设计、高层建筑与智能化建筑内部空间设计。     

Gods of the City? Reflecting on City Building Games as an Early Introduction to Urban Systems

For millions of gamers and students alike, city building games (CBGs) like SimCity and the more recent Cities: Skylines present a compelling initial introduction to the world of urban planning and development. As such, these games have great potential to shape players’ understanding and expectations of real urban patterns and processes. In this article I argue that, despite the fundamental role of agency in CBGs and other sandbox type games, players are constrained by the developers’ assumptions and biases regarding how cities ought to look and function. Of particular consideration is the tendency among CBGs to emphasize personal transportation over transit, autocentric over mixed-use development, and simplified social dynamics over a more realistic model.     

Africa’s middle class: building houses and constructing identities in the small town of Buea,Cameroon

Across Africa households are commissioning new domestic buildings for their own use or to rent out rather than waiting for governments to supply urban shelter. We conceptualize this as two interwoven processes: building houses for a new middle class and the building of a new middle class identity. We draw particular attention to the impact of international migration on these processes. The paper uses quantitative data from building permits and qualitative data from 29 interviews and walk-round tours with homeowners and government officials in Buea, Cameroon. Despite some significant caveats (related to housing the urban poor, regulating building standards, and lost local government revenue), we argue that these individually initiated building projects do a reasonable job of meeting local demand for shelter. However, from the perspective of identity-building these buildings are less successful. Whilst homeowners take considerable pride in their building projects, the statements that these structures make about their identities are not always “read” by their neighbours in the way owners hope. New housing is the lens through which Buea’s residents interpret growing levels of inequality and its associated social tensions.     

The Slums of Aspen: Immigrants vs. the Environment in America's Eden. Lisa Sun-Hee Park and David Naguib Pellow

In the past decade, Beijing has experienced dramatic spatial restructuring. In this paper, we test whether the conventional monocentric model of urban spatial structure can explain recent developments in Beijing’s land market. Using official land transaction data from 2008 through 2012, we find that (1) for commercial, mixed-use, and residential land parcels, both land prices and development intensities do not decline with distance from the urban center; (2) for industrial land parcels, land prices increase with distance from the urban center. These insignificant and positive land-price gradients defy the predictions of the monocentric model; such results are explained by examining Beijing’s evolution from a monocentric to a polycentric spatial configuration, which has been driven by various urban planning efforts and institutional reforms. Our analysis of post-Olympic Beijing land market dynamics leads to a fresh understanding of the city’s emerging polycentric metropolitan structure.     

基于改进DeepLabv3plus算法的遥感图像海岛建筑提取方法

目前海岛经济快速发展,为避免海岛建筑无序扩建,了解海岛建筑分布特征尤为重要。机器学习方法是从高分遥感影像提取地物目标的常见方式,然而建筑物遥感特征复杂,机器学习方法出现鲁棒性差、难以充分挖掘深层次特征的弊端。文章提出基于DeepLabv3plus网络模型的深度学习语义分割方法提取海岛建筑,并对网络结构进行改进,使用组归一化（GN）方法替代批归一化（BN）以适合小batch size下的语义分割操作。针对海岛建筑数据量较少的问题,采用迁移学习策略,设计基于多源数据的国内城市建筑数据集的预训练样本智能采集和标注方法,再人工标注中国部分海岛建筑进行算法实验。结果表明,在batch size较小时,基于GN的DeepLabv3plus语义分割算法的平均精度和mIoU均得到提升,能够获得更为精确的像素级海岛建筑提取结果。     

民国时期广州市建成区主体建筑立体形态的恢复及其特征

基于1928年1﹕10 000的地形图,解译土地利用类型,确定建成区边界与建筑用地的空间范围。将建筑用地分为单体建筑、线状道路两侧的骑楼和面状同类建筑区3类。根据史料与现场调查,分别为点、线、面3类建筑的高度赋值,恢复不考虑海拔的建成区主体建筑立体形态。基于所建模型,从平面形态、平均高度、空间格局、宽高比、高度轴、天际线以及形态组合几方面对民国时期建成区立体形态特征进行分析归纳,得出如下结论：１）民国时期广州城市沿珠江发展使得城区轮廓呈狭长的带状;２）城市平均高度仅为6.07 ｍ,建筑物普遍低矮;３）建筑物在平面上为多级的棋盘网组合,而骑楼街构成的宽浅网格,成为当时空间尺度最大的建筑单元组合形态;４）道路宽度与两侧建筑物高度形成的宽高比大,城市具有较好的通透性;５）沿江西路与当时的城市中轴线中山纪念堂―市府合署大楼构成了倒“T”型城市空间高度轴,并在单体建筑高度空间分布与天际线的变化上得到很好的反映;６）城市立体形态主要由盆地、格网、谷地、台地等4种宽浅的单元组成。立体形态深层次上反映了当时生产力技术条件下政府与市场力量的综合作用,以及城市功能区分化在立体形态上的表现,从而也成为该时期华南地区依山傍水城市立体形态的重要标志。     

天津市单次极端低温过程中城市热岛对建筑负荷的影响

基于自动气象站实测资料，通过模拟天津市办公建筑逐时供暖负荷，重点分析了极端低温过程中城市热岛对建筑小时供暖负荷的影响，以期为精细化供暖调控和节能设计提供参考。结果表明：2009—2017年城市和乡村办公建筑供暖负荷均呈减少趋势，城市供暖负荷较乡村平均每年减少7.46%。城市热岛强度(Urban heat island intensity, UHII)每上升1℃，城市办公建筑年供暖负荷较乡村减少2.19 kWh/m²，即热岛强度的增加使城市办公建筑供暖需求有所减少，有利于城市建筑的供暖节能。以2016年1月21~25日典型极端低温过程为例，研究发现，低温过程中城乡小时供暖负荷明显增加，较低温前和低温后增加约10%~20%。受大尺度天气过程影响，低温过程中城乡气温差异变小，UHII减弱。低温前和低温后城市供暖负荷较乡村减少约6%~8%，而低温过程中城市较乡村仅减少约3%；另外，在低温过程中，北京时间07:00~19:00的高负荷时段城乡供暖负荷差异不明显，这些结果表明低温过程中城市热岛对办公建筑供暖负荷的影响不大。     

Street as a big geo-data assembly and analysis unit in urban studies: A case study using Beijing taxi data

Quantitative research of urban geography has benefited greatly from the rapid development of big geo-data. Spatial assembly is an essential analytical step to summarize and perceive geographical environment from individual behaviours. Most research focuses on the methodology of how to utilize the big data, while the adopted spatial units for data aggregation remain areal in nature. This article conceptually proposes an idea of sensing cities from a street perspective, emphasizes the significance of street units in quantitative urban studies. Using a three-month taxi trajectory dataset and the major streets in Beijing, we explore the spatio-temporal patterns of urban mobility on streets, cluster streets into nine types based on their dynamic functions and capacities. Additionally, we discuss the differences and connections between the linear street unit and traditional areal units, investigate the possibility of uncovering urban communities using streets, and point out the complexity of streets. We conclude that street unit as a supplement to areal units, is able to effectively minify the modifiable areal unit problem (MAUP), sense urban dynamics, depict urban functions, and understand urban structures.     

Measurements of POI-based mixed use and their relationships with neighbourhood vibrancy

Although mixed use is an emerging strategy that has been widely accepted in urban planning for promoting neighbourhood vibrancy, there is no consensus on how to quantitatively measure the mix and the effects of mixed use on neighbourhood vibrancy. Shannon entropy, the most commonly used diversity measurement in assessing mixed use, has been found to be inadequate in measuring the multifaceted, multidimensional characteristics of mixed use. And lack of data also makes it difficult to find the relationship between mixed use and neighbourhood vibrancy. However, the recent availability of new sources including mobile phone data and Point of Interest (POI) data have made it possible to develop new indices of mixed use and neighbourhood vibrancy to analyse their relationships. Taking advantage of these emerging new data sources, this study used the numbers of mobile phone users in a 24-hour period as a proxy of neighbourhood vibrancy and used POIs from a navigation database to develop a series of mixed-use indicators that can better reflect the multifaceted, multidimensional characteristics of mixed-use neighbourhoods. The Hill numbers, a unified form of diversity measurement used in ecological literature that includes richness, entropy, and the Simpson index, are used to measure the degrees of mixed use. Using such fine-grained data sets and the Hill numbers allowed us to obtain better insights into the relationship between mixed use and neighbourhood vibrancy. Four models varying in POI measurements that reflect different dimensions of mixed use were presented. The results showed that either POI density or entropy can explain approximately 1% of neighbourhood vibrancy, while POI richness contributes significantly in improving neighbourhood vibrancy. The results also revealed that the entropy has limitations as a measure for representing mixed use and demonstrated the necessity of adopting a set of more appropriate measurements for mixed use. Increasing the number of POIs has limited power to improve neighbourhood vibrancy compared with encouraging the mixing of complementary POIs. These exploratory findings may be useful for adjusting mixed-use assessments and to help guide urban planning and neighbourhood design.     

BUILDING DENSITY AND INTERIOR BUILDING TEMPERATURES: A PHYSICAL MODELING EXPERIMENT

The effect of building density on the interior temperatures of buildings is explored using scaled physical models. The urban canopy layer is modeled as a single-cube structure surrounded by a wall that represents neighboring structures. Each physical model was constructed of plywood and consisted of a cube 200 mm in height, enclosed by a wall 200 mm in height. Four models were constructed corresponding to height/width ratios (H/W) of 4, 2, 1, and 0.5 and placed at an exposed site located at 34°N. The interior air temperature of each cube, direct and diffuse solar radiation on a horizontal surface, and ambient air temperature and wind velocity were measured over a period from late November 1996 to early June 1997. To extract the influence of building density, air temperatures were compared against those measured in the model representing a H/W of 1. The results show that nighttime cooling is primarily a function of building density, but that daytime heating depends on the interaction of density with changing model-sun relationships. [Key words: urban canopy layer, building air temperature, building density, physical model.]     

城市三维景观格局时空分异特征研究——以大连市中山区为例

以大连市中山区2003年、2013年城市三维建筑数据为基础,选取三维景观指标,运用ArcGIS空间分析方法从多个角度来研究城市10年间建筑景观格局时空分异特征。结果表明：① 大连市中山区建筑加权平均高度和体积分别增加7.87 m、277.25×10⁴ m³;地块覆盖率减少了16.27%,容积率增加了20.67%,反映出城市水平和垂直空间分别呈收缩、扩展的态势。② 中山区城市天际线起伏差异明显,东—西方向呈逐渐增高的趋势,南—北方向呈“北部高峰,中部和南部平缓”格局。城市高层建筑主要集中于城市的西北部,且2013年建筑最高点中心裕景比2003年宏进大厦高140 m。③ 建筑覆盖率和容积率在空间分布上差异明显,低和极低覆盖率与容积率地块所占比例大,分别增加了8.3%、-4.33%;高和极高覆盖率与容积率地块所占比例少,且集中分布在青泥洼桥和人民路街道。④ 2003年超高层建筑在空间分布上呈“聚集—离散”状态,即在距离660 m尺度范围内呈聚集状态,大于660 m时呈离散分布,其他三种建筑类型在空间上都呈一定的聚集分布状态;2013年4种不同类型建筑在空间分布上都呈现一定的聚集分布状态,聚集程度为：超高层建筑>低层建筑>多层建筑>高层建筑。     

An Extended Minimum Spanning Tree method for characterizing local urban patterns

Detailed and precise information on urban building patterns is essential for urban design, landscape evaluation, social analyses and urban environmental studies. Although a broad range of studies on the extraction of urban building patterns has been conducted, few studies simultaneously considered the spatial proximity relations and morphological properties at a building-unit level. In this study, we present a simple and novel graph-theoretic approach, Extended Minimum Spanning Tree (EMST), to describe and characterize local building patterns at building-unit level for large urban areas. Building objects with abundant two-dimensional and three-dimensional building characteristics are first delineated and derived from building footprint data and high-resolution Light Detection and Ranging data. Then, we propose the EMST approach to represent and describe both the spatial proximity relations and building characteristics. Furthermore, the EMST groups the building objects into different locally connected subsets by applying the Gestalt theory-based graph partition method. Based on the graph partition results, our EMST method then assesses the characteristics of each building to discover local patterns by employing the spatial autocorrelation analysis and homogeneity index. We apply the proposed method to the Staten Island in New York City and successfully extracted and differentiated various local building patterns in the study area. The results demonstrate that the EMST is an effective data structure for understanding local building patterns from both geographic and perceptual perspectives. Our method holds great potential for identifying local urban patterns and provides comprehensive and essential information for urban planning and management.