合肥市卫星定位连续运行基准站网融合改造的实践探讨

为了更好地服务于自然资源和规划,建立合肥市统一的卫星定位连续运行参考站(CORS)．针对当前合肥市三套卫星定位CORS独立运行、基准框架和服务标准不统一的问题,从基准站深度融合建设、系统软硬件升级、现有软硬件的兼容性、组网设计和CORS基准框架坐标联测与扩展服务的实践展开探讨. 综合运用了多种共享融合技术,通过外业实测验证方法的正确性和可行性,对城市CORS融合改造具有很好的借鉴意义.      

城市绿地信息提取中高分辨率卫星影像融合方法研究

利用GS变换、主成分分析、Ehlers变换、Wavelet分析、HIS变换5种方法对城区WorldView-2和PL-1A影像进行融合,并从影像融合质量和绿地信息提取精度两方面对融合方法的有效性进行了评价。结果表明：①5种融合方法中,GS变换融合的效果最好;主成分分析和Ehlers变换融合WorldView-2质量较好,但融合PL-1A影像质量较差;Wavelet变换、HIS变换融合两种影像质量都较差;②用于绿地信息提取时,GS、PCA融合影像获取的精度最高,其次为Ehlers、Wavelet融合影像,均明显高于多光谱影像的提取精度;Ehlers、Wavelet变换精度最低,绿地信息提取精度低于多光谱影像的提取精度。可以得出,影像融合可以明显地提高绿地信息提取精度,5种影像融合方法中,GS变换普适性较好,影像融合质量最好,提高分类精度效果最明显。     

UD-SV: Urban data services and visualization framework for sharing multidisciplinary research

With the widespread availability of a large volume of urban data, stakeholders from different domains require advanced tools to manage, visualize and understand cities and their evolution. During the last few years, researchers have proposed numerous research works and applications to illustrate the cities of the past and possible scenarios of the future under different conditions. However, many of these approaches are one-time solutions and not based on standards, making them obsolete and unusable for reproducible research. In this article, we present UD-SV: an Urban data-Services and Visualization open-source framework for multidisciplinary research to handle complex processing, analysis, and visualization of urban data. However, our goal is not to present a one-time monolithic software solution for urban data management and analysis, but we demonstrate the design and development of an open and interoperable software framework driven by use cases from diverse users to solve applied research challenges. The main contribution of UD-SV is that it uses open standards and open data with documented and reproducible processes with a particular emphasis on the reuse of existing open-source software components. We also show an enhanced use of standards to enable a shift toward components that are interchangeable or composable with other existing components in the GIS community.     

Selection of a Landfill Site for Solid Waste Management: An Application of AHP and Spatial Analyst Tool

Selection of a suitable landfill site for Solid Waste Management (SWM) forms an important component of urban planning. The problem of SWM has assumed significant proportion for the municipal authorities in the wake of rapid industrialization, urbanization and resultant pressure on existing resources. Many criteria such as distance from residential locations, transport connectivity, presence of water-bodies (drains, ponds, rivers etc.) and forests, ground water table and geology are taken into consideration while planning for suitable sites. Spatial Analyst Tool along with Analytic Hierarchy Process (AHP) model is extremely useful in such multicriteria decision making process. The present study, based on these tools/techniques, endeavours to identify a suitable location for landfill site in a part of the National Capital Territory of Delhi. The study identifies six potential sites out of which one has been proposed and recommended as the best suitable site.     

保持城市道路格网模式的街区合并混合整数规划模型

基于最优化建模理论提出一种保持城市道路格网模式的街区合并混合整数规划模型。首先定义道路格网模式保持的目标函数,集成了紧密性、骨干性、排列一致性和合并方向性四个评价指标;然后构建四个合并约束条件,包括合并尺度、路划删除、联动合并和连通性保持,来保证合并过程正确有效且满足目标尺度需求,;最后利用已识别的主干道和格网模式对道路网进行分区,在保持道路网的骨架和格网结构模式的基础上对每个分区内的道路街区独立建立最优化合并模型。本文采用数学最优化规划程序CPLEX对模型进行求解。。实验使用ATKIS 1:25000数据,将其简化至1:100000并与已有数据作比较。结果表明,通过本方法简化的道路网能够保持道路网中整体和局部的模式特征。     

重庆市城市用地现状遥感调查研究

此文主要介绍利用航空彩红外像片对重庆市城市用地现状进行调查研究的过程,详细论述了进行城市用地类型解译的方法、解译标志与影像特征,基本查明了重庆市城市用地面积和现状分布,在此基础上分析讨论了重庆市城市用地现状的特点,指出了城市用地存在的主要问题。     

Hedging against service disruptions: an expected median location problem with site-dependent failure probabilities

The vector assignment p-median problem (VAPMP) (Weaver and Church in Transp Sci 19(1):58–74, 1985) was one of the first location-allocation models developed to handle split assignment of a demand to multiple facilities. The underlying construct of the VAPMP has been subsequently used in a number of reliable facility location and backup location models. Although in many applications the chance that a facility fails may vary substantially with locations, many existing models have assumed a uniform failure probability across all sites. As an improvement, this paper proposes a new model, the expected p-median problem as a generalization of existing approaches by explicitly considering site-dependent failure probabilities. Multi-level closest assignment constraints and two efficient integer linear programming (ILP) formulations are introduced. While prior research generally concludes that similar problems are not integer-friendly and cannot be solved by ILP software, computational results show that our model can be used to solve medium-sized location problems optimally using existing ILP software. Moreover, the new model can be used to formulate other reliable or expected location problems with consideration of site-dependent failure probabilities.     

A New 3‐D Solar Radiation Model for 3‐D City Models

Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2‐D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3‐D approach. This study presents a new 3‐D solar radiation model for urban areas represented by 3‐D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3‐D vector data representing complex urban environments. The calculation procedure is based on the combined vector‐voxel approach segmenting the 3‐D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces.     

Sensing Sprawl: Towards the Monitoring of Urban Expansion Using Dempster‐Shafer Theory

Abstract

The outward expansion of cities in the United States has been a source of concern and policy debate for well over forty years. This sprawling urban landscape has been cited as a contributing factor behind the loss of open space, environmental damage and increased congestion. To better understand urban expansion, monitoring programs are required to facilitate the systematic observation of urban expansion, and to provide critical information in order to adjust urban development policies. Monitoring the urban landscape has been a major application focus of satellite remote sensing technologies. Yet, research has shown that the complexity of the urban landscape frustrates simple characterization of cumulative land cover processes such as sprawl. In this paper an approach to the remote detection and characterization of sprawl is introduced based on the use of Dempster‐Shafer Theory of Evidence. Functioning as a soft‐classification algorithm, Demptster‐Shafer Theory offers a unique solution to the mapping problem when evidence of class structure in underscored by uncertainty. Through the use of this technique it was possible to model uncertainty based on the concept of belief. This conceptualization was instrumental in deciphering the complexities of urban land cover arrangements and offered an alternative logic which enhanced delineation of subtle changes in land cover indicative of sprawl.     

利用角点进行高分辨率遥感影像居民地检测方法

传统的城区检测方法大多是基于影像的全局特征,如纹理、光谱、形状等。当影像出现尺度、光照等条件变化时,将导致这些特征出现变化,造成算法的稳健性下降。而局部不变特征（例如,角点）却不易受到这些因素的影响。为此,本文提出一种无监督的基于角点特征的高分辨率遥感影像城区检测方法。该方法首先在传统的Harris算子的基础上,加入局部和全局约束准则检测影像中的角点,然后根据影像中角点的分布情况,自适应地构建似然函数来度量影像中每一个像素点属于城区的概率,最后采用二值分割的方法提取影像中的城市区域。实验结果表明：该方法可以快速、可靠地检测到影像中的城市区域,具有较高的实际应用价值。     

城市规划建筑面积指标自动化计算方法探讨

针对建筑面积指标计算方法当前各地复杂且不统一的问题,该文从建筑的层级结构出发,介绍了规划建筑面积指标的自动化计算模型,详细阐述了建筑空间基本面积、公摊面积,以及单体建筑面积指标与建设项目宏观面积指标的计算方法,并在此基础上开发相关软件,实现了城市规划建筑面积指标的自动化计算。     

无人机倾斜摄影结合激光扫描仪三维逆向建模

近年来随着科学技术水平的不断提高,城市三维数字化成为数字城市建设的重点应用方向.无人机遥感技术、三维激光扫描技术的发展,使数字城市建设逐渐开始向全面自动化、智能化转变.本文利用拓普康猎鹰8号多旋翼无人机,并结合拓普康GLS-2000L三维激光扫描仪对建筑物进行数据采集,然后利用Context Capture自动建模后处...     

利用图割算法进行城市密集点云表面模型重建

利用倾斜影像获得的密集点云来构建表面模型是基于倾斜影像进行三维重建的核心之一。本文针对现行密集点云表面模型重建存在的建模效率低、表面选取不真实等问题,提出了一种基于图割算法的城市密集点云表面模型重建方法。利用该方法重建城市密集点云表面模型,首先通过预处理软件对无人机倾斜影像进行空中三角测量,并利用空中三角测量的解算结果生成密集点云;然后对密集点云添加相应的边,同时对三维点云根据距离进行选取合并;最后根据三维点云形成的四面体和三角面建立图割问题,并通过求解图割问题来求取最优的密集点云表面模型。为证明这种方法的可行性和有效性,使用城市地区的无人机倾斜影像数据进行城市密集点云表面模型重建,试验结果表明,该方法具有可行性好、建模效果好、处理速度快等优势。     

Results of the ISPRS benchmark on urban object detection and 3D building reconstruction

For more than two decades, many efforts have been made to develop methods for extracting urban objects from data acquired by airborne sensors. In order to make the results of such algorithms more comparable, benchmarking data sets are of paramount importance. Such a data set, consisting of airborne image and laserscanner data, has been made available to the scientific community by ISPRS WGIII/4. Researchers were encouraged to submit their results of urban object detection and 3D building reconstruction, which were evaluated based on reference data. This paper presents the outcomes of the evaluation for building detection, tree detection, and 3D building reconstruction. The results achieved by different methods are compared and analysed to identify promising strategies for automatic urban object extraction from current airborne sensor data, but also common problems of state-of-the-art methods.     

Geographical information system-based groundwater quality index assessment of northern part of Kolkata,India for drinking purpose

Groundwater is a resource under stress. In both developed and developing countries, it has been found that increasing human influence has led to the contamination of the groundwater resource. To understand the magnitude of this problem, a study was conducted in 58 wards within Northern part of Kolkata, India, where water samples from tube wells were collected and analysed on essential drinking water quality parameters, prescribed by WHO. Using Principal component analysis, and Water quality index mapping, the aforementioned results have been interpreted. This has helped to depict that not only is the groundwater unsuitable for drinking, but that the parametric values have a tendency to increase abruptly within the shortest of ranges, indicating urban pollution as the root cause of contamination. This paper shall thus discuss the spatial change in groundwater quality in northern Kolkata and suggest measures which might be implemented to secure a sustainable future for the city.     

Voronoi图在城镇地价指数监测中的应用探讨

城市地价指数是地价动态监测的重要手段。针对我国城市地价指数测算公式发表了自己的见解,并提出采用Voronoi图计算地价监测点的影响范围,作为监测样点的权重用于计算地价指数的方法,以广东省某市的地价指数测算为例证明了该方法的可行性。     

基于XQuery的GML查询语言研究

随着GML规范的不断完善及GIS软件厂商的广泛支持,越来越多的空间数据以GML格式存储,GML空间数据的查询已成为GIS研究的热点问题。传统的关系数据库查询语言SQL是针对平面的二维关系数据而设计的,并不适合XML/GML半结构化数据的查询;商品化GIS软件的查询系统只能查询自身的空间数据而无法查询其它GIS系统的空间数据;XML查询的研究为GML查询奠定了一定的基础。首先针对GML查询存在的问题,提出了扩展XQuery是GML查询语言实现的最佳选择;结合XML查询语言和空间数据查询语言,提出了GML查询语言的特征和GML查询语言系统框架;并根据GML空间数据的特点,以XML标准查询语言XQuery为基础,提出了XQuery空间扩展的内容;开发了GML空间数据查询语言GMLXQL,实现了GML空间数据的本原查询。     

An artificial neural network based approach for urban growth zonation in Dehradun city,India

For regulating urban growth, it is imperative to produce urban growth zonation maps, in which future urbanizable areas along with their urban growth potential are delineated. As, these maps provide a rational and scientific basis for taking future decisions regarding the growth of the city. The conventional approach for generating urban growth zonation maps is subjective in nature. To reduce this subjectivity, an artificial neural network (ANN) approach has been proposed for generating urban growth zonation maps. The database required for ANN-based urban growth zonation has been compiled from remote sensing data and other existing maps. GIS is used for handling of this spatial data. A comparison of the ANN- and conventional approach-derived zonation maps was also done. The study demonstrated the potential of ANN for urban growth zonation of an area, which may provide a valuable input to the urban planning authorities for regulating urban growth     

State-of-the-art of elevation extraction from satellite SAR data

Relative or absolute elevation extraction from satellite radar data has been an active research topic for more than 20 years. Various investigations have been made on different methods depending on the predominant “fashion” and data availability, leading each time to new developments to improve the capability and the applicability of each method. The paper presents an update of the state-of-the-art of elevation extraction from satellite SAR data. The performance and limitations of four different methods (clinometry, stereoscopy, interferometry and polarimetry) are reviewed, as well as their applicability to different satellite SAR sensors. Their advantages and disadvantages and how they are addressed during the data processing are also analysed. Finally, concluding remarks look at the complementarity aspects of each method to make the best use of the existing and future radar data for elevation extraction.