Multi‐Scale Geometry Interpolation

Interpolating vertex positions among triangle meshes with identical vertex‐edge graphs is a fundamental part of many geometric modelling systems. Linear vertex interpolation is robust but fails to preserve local shape. Most recent approaches identify local affine transformations for parts of the mesh, model desired interpolations of the affine transformations, and then optimize vertex positions to conform with the desired transformations. However, the local interpolation of the rotational part is non‐trivial for more than two input configurations and ambiguous if the meshes are deformed significantly. We propose a solution to the vertex interpolation problem that starts from interpolating the local metric (edge lengths) and mean curvature (dihedral angles) and makes consistent choices of local affine transformations using shape matching applied to successively larger parts of the mesh. The local interpolation can be applied to any number of input vertex configurations and due to the hierarchical scheme for generating consolidated vertex positions, the approach is fast and can be applied to very large meshes.     

Analysing the consistency between built-up areas and human activities and the impacts on the urbanization process: a case study of Zhengzhou,China

Urbanisation is accompanied by drastic urban sprawl and populations gathering in cities. The new urban districts in China have gradually become the most effective form of built-up area expansion, but the corresponding human activities within these built-up areas have not increased at the same rate, which has led to the emergence of urbanisation-related problems, such as ghost cities. However, few studies have focused on the evolution of this inconsistency within a city, especially at multiple scales. Based on Landsat images and the Defense Meteorological Satellite Programme-Operational Linescan System (DMSP-OLS) data, our study calculated the barycentre, the agglomeration degree and the consistency index to quantitatively analyse the spatio-temporal consistency between built-up areas and human activities within a city from 1993 to 2013. A mainstream urban example in China, Zhengzhou, which accepted financial and policy support from the government and underwent rapid urbanisation, was chosen as a case study. The results of this study showed that (1) the consistency between built-up areas and human activities was characterised by an approximately S-shaped curve that divided the city’s development into three stages, namely, relative stability (1993–1998), rapid development exhibiting inconsistency (1998–2008) and the optimisation and matching of spatial factors (2008–2013); (2) the inconsistency stage had two diametrically opposed patterns: the increase in human activities lagged behind the expansion of built-up areas, and the opposite occurred in older areas, which resulted in the emergence of ghost cities in new districts and crowded populations in the old cities; and (3) the inconsistency stage occurs easily; thus attention should be paid during the promotion of urbanisation processes in rapidly developing cities such as Zhengzhou; however, as the urban population increases, under economic development and a policy of unceasing expansion, the area of inconsistency was mitigated after 2010. Our findings illustrated the influence of consistency on built-up areas and human activities in terms of coordinated development within cities and provided a better understanding of the urbanisation process in Chinese cities.     

Airborne experimental measurements of the angular variations in surface temperature over urban areas: case study of Marseille (France)

The directional surface temperatures over urban areas are measured using an airborne TIR camera equipped with wide-angle lenses. The experimental design is described and the possible sources of errors related to the instruments and the atmosphere are analysed and corrections proposed. The data acquisition protocol is adapted to provide directional TIR measurements in a −60° to +60° range for zenith and 0 to 360° for azimuth view angles. Two parts of the city of Marseille, the densely built old city centre and a built/vegetated mixture of individual houses and gardens in a suburb, have been studied during summer 2001 in the framework of the UBL-ESCOMPTE project. The results obtained reveal important hot spot effects and differences of surface brightness temperatures varying between −5 and 7 K between nadir and off-nadir measurements, according to azimuth view angles. Acquisitions performed over the two areas also illustrate the impact of the surface structure and presence of vegetation on the hot spot. An example application for the correction of two temporal series of NOAA 14 and NOAA 16 data is given.     

基于多层次特征结构的二维形状渐变

二维形状渐变在二维角色动画、模式匹配、几何造型中有着重要的应用.已有方法大多根据边长、角度、面积等局部几何属性来完成形状之间的最佳对应和渐变,忽略了形状的内在特征结构.为此,提出一种基于多层次特征结构的二维形状渐变方法,首先将源形状和目标形状分解为若干个视觉显著性特征,并通过一种用户启发式的半自动方法建立2个形状的特征对应关系;然后根据形状的特征信息构建源形状和目标形状的多层次特征结构,分别表示形状特征的整体位置和朝向、形状特征的局部朝向和形状特征的局部细节;最后组合不同特征层次上的插值结果,重构出中间形状.在源形状到目标形状的渐变过程中,针对不同层次上的特征信息分别使用近似保刚性插值、边角插值以及弹性线性插值方法进行过渡.实验结果表明,该方法简单高效,有效地避免了形状的内部扭曲,保持了形状的局部特征,可产生自然、光滑且视觉真实的形状渐变序列.     

互联网空间下的城市网络格局及结构研究*

大数据时代,互联网成为科学研究的有效工具和平台。借助百度搜索指数数据,运用复杂网络方法构建互联网空间下有向加权城市网络模型,分析互联网上的城市网络格局及复杂结构。以我国36大城市数据为样本,实证发现该城市网络的节点出权及入权累积分布均符合指数分布,归类网络中的城市活跃类型,计算挖掘出网络中的关键城市节点以及网络的凝聚子群。从互联网新媒介视角对“互联网 ”计划下城市网络结构做出了新的解析,丰富了城市复杂网络的研究,对城市的建设规划、管理具有指导意义。     

基于PM模型的曲面去噪变分水平集方法

PM（perona-malik）模型是一种经典的非线性图像扩散模型,该模型能根据设定的阈值对图像光滑区域进行扩散,并能自适应地保持图像边缘。本文将曲面法矢量与一般灰度图像的强度进行类比,将经典的图像扩散的PM模型转化为曲面几何噪声处理的自适应扩散变分模型,在使曲面光滑的同时,能够保持曲面边缘。曲面采用隐函数的零水平集表达,能量泛函中的数据项用初始水平集函数的Heaviside函数与演化后水平集函数的Heaviside函数差的平方表达,能量泛函中的光滑项基于几何曲率定义。此外,在能量泛函中增加了水平集函数为符号距离函数的惩罚项,避免了水平集函数需要不断重新初始化的问题。数值实验验证了所提出模型的曲面噪声去除及曲面边缘保持效果。     

Constructing Virtual Cities by Using Panoramic Images

Simultaneously acquired omni-directional images contain rays of 360 degree viewing directions. To take advantage of this unique characteristic, we have been developing several methods for constructing virtual cities. In this paper, we first describe a system to generate the appearance of a virtual city; the system, which is based on image-based rendering (IBR) techniques, utilizes the characteristics of omni-directional images to reduce the number of samplings required to construct such IBR images. We then describe a method to add geometric information to the IBR images; this method is based on the analysis of a sequence of omni-directional images. Then, we describe a method to seamlessly superimpose a new building model onto a previously created virtual city image; the method enables us to estimate illumination distributions by using an omni-directional camera. Finally, to demonstrate the methods' effectiveness, we describe how we implemented and applied them to urban scenes.     

Structure-Preserving Reshape for Textured Architectural Scenes

Modeling large architectural environments is a difficult task due to the intricate nature of these models and the complex dependencies between the structures represented. Moreover, textures are an essential part of architectural models. While the number of geometric primitives is usually relatively low (i.e., many walls are at surfaces), textures actually contain many detailed architectural elements.
We present an approach for modeling architectural scenes by reshaping and combining existing textured models, where the manipulation of the geometry and texture are tightly coupled. For geometry, preserving angles such as oor orientation or vertical walls is of key importance. We thus allow the user to interactively modify lengths of edges, while constraining angles. Our texture reshaping solution introduces a measure of directional autosimilarity to focus stretching in areas of stochastic content and to preserve details in such areas.
We show results on several challenging models, and show two applications: Building complex road structures from simple initial pieces and creating complex game-levels from an existing game based on pre-existing model pieces.     

中缅边境典型城市扩张遥感动态监测及驱动力分析

在“一带一路”背景下,当前针对边境城市建成区发展的研究尚不充分,特别境内外口岸毗邻城市的演化交互关系更有待挖掘。以中缅边境地区典型的口岸毗邻城市——瑞丽市和木姐市作为研究区,选取2012、2015和2018年遥感影像,采用城镇建筑用地指数提取两市建成区,从建成区扩张数量、空间分布格局和内部经济规模3个方面,分析瑞丽市开发开放试验区设立后的两市建成区动态变化特征,并对两市建成区演化的交互关系和扩张驱动因素进行探讨。结果表明：在自然环境、经济产业、政策规划、交通、口岸等因素的综合作用下,两市建成区扩张明显。瑞丽市城市西部扩张最为明显,东部次之,呈现“一体两翼”式扩张格局,逐渐从建成区外延转为内部填充及基础设施完善阶段;木姐市主要向西北和正东方向扩张,建成区保持较为明显的外延特征,但其内部土地集约利用水平不高。在交互协同发展过程中,瑞丽市占主导地位,木姐市处在依附地位。两市的快速协同扩张也体现了中缅两国政治经济的紧密交流和广阔的合作空间。     

边缘计算和云计算在智慧城市建设中的应用

文章主要对边缘计算、云计算的定义和特点及智慧城市的概念进行简单阐释,结合城市建设情况,分析边缘计算和云计算在智慧城市建设中应用的必要性,并提出二者的具体应用,希望充分挖掘边缘、云计算技术的优势,在二者相互补充的过程中实现智慧城市的建设,为实际智慧城市建设工作提供参考依据。     

Agglomeration centrality to examine spatial scaling law in cities

Cities grow with processes resulting in the agglomeration of population and socioeconomic activities. At any stage of urban development, a city possesses a spatial structure of urban fabric to facilitate its functions. In this study, we find that the agglomeration characteristics of a city are significant for the identification and understanding of urban spatial structure. We propose a new centrality measure, termed agglomeration centrality, to examine the centrality of a node based on its relative level of clumpiness in an urban road network. We show a simple method to computationally define the agglomeration centrality based on Voronoi tessellations of all nodes in the network. On this basis, we investigate the spatial distribution of agglomeration centrality of urban road networks. Experiments on a set of randomly selected cities show that the agglomeration distributions of all these urban street networks present a remarkable double-power-law phenomenon. The distribution of the agglomeration centrality measures shows an invariant spatial scaling rule for cities. The regions with the highest centralities are always found to be urban centers. In comparison, this cannot be achieved by any current centrality measures. Finally, in an effort to explore the potential additional applicability of the new centrality measure to aid our understanding of spatial structures of other urban demographic or socioeconomic attributes, the agglomeration centrality was combined with the population data to create a population agglomeration index. The distribution of this index indicates a single-power-law property. In summary, this study develops a new centrality measure and demonstrates its effectiveness for understanding the spatial structures and spatial evolution of cities.     

基于云技术的智慧城市中大规模房屋数据处理

在智慧城市中传感器和设备收集各种数据,实现增值服务.主要关注来自智慧城市中的智能房屋数据,提出用于存储和处理大规模房屋数据的Scallop4SC平台,实现智慧城市服务.房屋数据分为房屋日志数据和房屋配置数据,分别使用HBase和MYSQL管理.通过HBase键值以schemaless方式存储管理异构日志数据.MySQL管理配置数据,完成房屋数据查询.多节点Hadoop/Map Reduce集群处理巨量房屋日志数据.最后通过实际一年的房屋日志数据,计算智能设备能耗并完成实验性评估.根据实验结果,探讨Scallop4SC处理智慧城市的数据规模.     

面向对象的损毁建筑物提取

地震灾害已经成为一种频发的自然灾害之一,在震后的灾害评估中,建筑物的倒塌情况是很重要的一项指标。本文用GeoEye影像提取海地地震中的损毁建筑物。由于海地地震时发生倒塌的房子大多处于比较老旧的地区,房屋比较密集,而且房顶结构也比较复杂,我们采取了一种基于规则集的方法通过分类将倒塌建筑物逐步与其他各种地物区分开来。即在影像多尺度分割的基础上,结合纹理特征及几何特征,通过规则集的方法构成分类树提取损毁房屋。另外在进行植被剔除时本文根据影像的特点提出了一种新的植被指数geo-NDVI,最后根据目视解译的结果对分类的结果进行了对比。     

基于B/S模式的房屋销售管理系统的设计与实现

对于房屋销售企业来说,各经营网点分布在同一城市的不同区域或不同城市,必须在充分利用原有信息和资源的基础上处理好许多中间环节,减少人员工作量,提高管理效率,设计了基于B/S模式的房屋销售管理信息系统的技术方案,并详细讨论系统的功能设计以及实现技术.     

基于ARIMA模型的二手房价格预测

 摘要： 近年来，我国一二线城市房价持续上涨，房屋成了人们日常生活讨论的热门话题，大家纷纷对未来的房价走势做出猜测。本文爬取国内某知名大型房产网站自2013年以来广州和深圳的二手房均价数据，采用ARIMA模型对未来的房价进行滚动预测，并使用RMSE对预测精度进行判断。结果表明，该模型可以对二手房均价进行持续预测，且预测精度较高，可为房屋买卖者提供参考。     

基于遥感和微博签到数据的住房空置空间识别

房屋空置率是衡量房地产市场健康与否的重要指标。基于夜间灯光遥感数据和全国土地覆盖数据,对房屋空置率进行空间识别。利用微博签到数据,通过基于密度的聚类算法和热力分析对居民活动空间强度进行分析,从“鬼城”指数排名靠前的100个城市中随机选择30个样本城市,进行城市内部房屋空置空间识别。结果表明：2013年全国地级及以上城市基于像元的平均房屋空置率为27.3%。东部地区房屋空置率较低,中西部地区房屋空置现象明显;房屋空置在中小型城市更加突出。     

Study on the Spatial Identification of Housing Vacancy

Housing Vacancy Rate (HVR) is an important index in assessing the healthiness of residential real estate market. Due to lack of clear and effectively evaluation criterion, the understanding of housing vacancy in China is then rather limited. This paper quantitatively analyzed spatial identification and difference pattern of house vacancy at different scale in China by using nighttime light data and micro-blog check-in data, in order to make up the deficiency of traditional methods in the aspects of data missing and differential approach. The nighttime light intensity for non-vacancy area is estimated after removing the nighttime light intensity from non-residential sources of NPP-VIIRS light data and difference of nighttime light caused by the different urban area ratio. Then, the HVR is calculated for the spatial pattern analysis. This paper analyzed the spatial strength of residents activities by using micro-blog check-in data, based on density-based spatial clustering of applications with noise and heat map. The 30 sample cities were selected to identify house vacancy from 100 cities which ghost city index were high. The following conclusions were drawn through the study: The HVR of eastern coastal cities and regions with rapid development of economy were lower, while the phenomenon of house vacancy in central and western regions were more obvious. The HVR increased from eastern coastal regions to inland areas. What’s more, the phenomenon of house vacancy in middle and small cities were more distinct from the aspect of urban scale. The house vacancy of China were divided into five types: industry or resources driven, government planned, epitaxy expansionary, environmental constraint and speculative activate by taking the factors of natural environment, social economic development level, and population density into consideration. This may shed light on policy implications for Chinese urban development.