多分析尺度下综合判别的地形元素分类方法

地形元素（如山脊、沟谷等）是地表形态类型基本单元,通过地形元素的不同空间组合可形成更高级别的地貌类型。现有的地形元素提取方法大多依靠地形属性计算,难以克服地形元素的空间相关性表达与局部地形属性计算存在不对应的矛盾,Jasiewicz和Stepinski提出的Geomorphons方法——基于高程相对差异信息进行地形元素分类,可避免这一问题,但Geomorphons方法本质上是在单一分析尺度上选择地形特征点用于判别,易受局部地形起伏的影响而造成误分类。针对这一问题,设计出一种多分析尺度下综合判别的地形元素分类方法。应用结果表明：相比Geomorphons方法,利用该方法得到的地形元素的分类结果更为合理。     

Surface modeling of DEMs based on a sequential adjustment method

A sequential adjustment (SA) method is employed to decrease the computational cost of high-accuracy surface modeling (HASM), and the SA of HASM (HASM-SA) is being developed. A mathematical surface was used to comparatively analyze the computing speed of SA and the classical iterative solvers provided by MATLAB 7.7 for solving the system of linear equations of HASM. Results indicate that SA is much faster than the classical iterative solvers. The computing time of HASM-SA is determined by not only the total number of grid cells but also the number of sampling points in the computational domain. A real-world example of surface modeling of digital elevation models (DEMs) with various resolutions shows that HASM-SA is averagely more accurate and much faster than the commonly used interpolation methods, such as inverse distance weighting (IDW), kriging, and three versions of spline, namely regularized spline (RSpline), thin-plate spline (TPS), and ANUDEM in terms of root mean square error (RMSE), mean absolute error (MAE), and mean error (ME). In particular, the ME of HASM-SA at different spatial resolutions is averagely smaller than those of IDW, kriging, RSpline, TPS, and ANUDEM by 85%, 83%, 83%, 53%, and 19%, respectively. The high speed and high accuracy of HASM-SA can be due to the absence of matrix inversion computation, combined with the perfect fundamental theorem of HASM.     

北京一号卫星影像的数据融合研究

"北京一号"卫星是我国近期发射的一颗中高分辨率对地观测小卫星.鉴于数据融合技术在遥感领域的重要作用,对该卫星多光谱与全色波段数据进行不同融合方法的实验.具体以河南新郑地区为实验区,应用遥感处理软件,通过定性分析和定量评价,得出Brovey变换是目前较适合北京一号小卫星数据的融合方法,而小波HIS变换则是以后研究的重要发展趋势.     

基于小波变换和局部相关系数改进IHS变换的图像融合方法

为得到分辨率高、光谱畸变小的融合图像,该文根据图像处理理论和小波变换的时频局部 特性,采用Quickbird数据,对多光谱波段经IHS变换的I分量和全波段图像分别进 行小波分解,用全波段图像经小波分解得到的高频系数替换I分量小波分解的高频系数, 替换时根据图像的地物光谱特性引入局部相关系数进行有选择的高频替换.经过IHS反变换得到空间分辨率高且没有光谱畸变的融合图像.     

Spatio-temporal analysis of territorial changes from a multi-scale perspective

The full integration of time dimensions in GIS still represents a research challenge. A number of systems provide ways to visualise harmonised timestamped geographical data onto maps, with interpolated curves representing how these data have changed over time. However, these systems frequently mask the concerns linked to changes in territorial organisations and the harmonisation of data. In fact, the development of a territory should be considered in connection with its neighbourhood, governance and genealogy relationships. This article focuses on the difficulties linked with the ‘change of support problem’, which can arise when conducting spatio-temporal analysis of data. First, we present a data model handling the changing relationships between territories. Then, we illustrate how this model can be instantiated using examples that have taken place in Europe. We show how the model can address questions such as that of change blindness. Finally, we explain how hierarchical and genealogical relationships can be used inside an interactive cartographic tool for spatio-temporal analysis. It provides various views of the same phenomena at multiple scales, through an approach that takes into account the changes in territorial organisation.     

Digital map conflation: a review of the process and a proposal for classification

This article is centred on analysing the state of the art of the conflation processes applied to geospatial databases (GDBs) from heterogeneous sources. The term conflation is used to describe the procedure for the integration of these different data, and conflation methods play an important role in systems for updating GDBs, derivation of new cartographic products, densification of digital elevation models, automatic features extraction and so on. In this article we define extensively each conflation process, its evaluation measures and its main application problems and present a classification of all conflation processes. Finally, we introduce a bibliography which the reader may find useful to further explore the field. It tries to serve as a starting point and direct the reader to characteristic research in this area.     

基于GF-1与Sentinel-2融合数据的地膜识别方法研究

随着我国地膜使用面积的增加和人们对土壤微塑料污染问题的日益关注,大尺度的地膜遥感识别已成为农业生产管理、土壤污染防治的必要手段。针对地膜光谱反射特征的复杂性以及基于单一遥感影像光谱特征识别方法错分率高等问题,该文以河北省邯郸市邱县为试验区,利用GF-1数据的空间细节与Sentinel-2数据的光谱信息进行NN Diffuse Pan Sharpening融合,据此建立地膜识别的特征矩阵(NDVI、MNDWI、NDBI、IBI、PSI),基于该特征矩阵可实现自动阈值地膜分层分类识别。多种方法的地膜识别结果精度对比表明:多源光学遥感数据融合方法的总体精度为94.87%,Kappa系数达0.89,显著优于基于单一数据源的深度学习法的精度(93.14%)以及基于传统机器学习分类方法的支持向量机(85.91%)和随机森林分类法(86.78%)的精度;通过与Sentinel-2多光谱影像融合,弥补了GF-1数据光谱分辨率低的缺陷,实现了多源数据在地膜识别中的优势互补,可为相关部门农业规划与管理以及生态环境保护等研究提供大尺度、高精度的地膜分布参考数据。     

闽南丘陵区典型小流域空间框架数据采集与应用

综合利用Photoshop、Geoway、MapInfo、ArcView等软件提供的处理技术,通过对扫描得到的地形、土地利用和水土流失等要素图进行图像剪切、拼接、配准、采样、跟踪、调整以及属性表的维护等一系列处理步骤,建立了大比例尺小流域地理空间框架数据集,提供了小流域空间框架数据采集与应用的技术流程与方法,提出应用各种软件进行大比例尺空间框架数据处理过程中应当注意的各种细节问题.最后,以闽南丘陵地区草子坝小流域为例,利用ArcView的3D Analyst、Spatial Analyst、Geoprocessing等扩展模块以及MapInfo SQL查询功能,对流域空间框架数据进行处理,得到了用于比较精细空间尺度上表达流域三维地形模型、坡度、坡向、河流垂直剖面、晕渲,不同高程上的土地利用类型等专题应用结果.     

闽南丘陵区典型小流域空间框架数据采集与应用

综合利用Photoshop、Geoway、MapInfo、ArcView等软件提供的处理技术,通过对扫描得到的地形、土地利用和水土流失等要素图进行图像剪切、拼接、配准、采样、跟踪、调整以及属性表的维护等一系列处理步骤,建立了大比例尺小流域地理空间框架数据集,提供了小流域空间框架数据采集与应用的技术流程与方法,提出应用各种软件进行大比例尺空间框架数据处理过程中应当注意的各种细节问题.最后,以闽南丘陵地区草子坝小流域为例,利用ArcView的3D Analyst、Spatial Analyst、Geoprocessing等扩展模块以及MapInfo SQL查询功能,对流域空间框架数据进行处理,得到了用于比较精细空间尺度上表达流域三维地形模型、坡度、坡向、河流垂直剖面、晕渲,不同高程上的土地利用类型等专题应用结果.     

A semantic registry using a Feature Type Catalogue instead of ontologies to support spatial data infrastructures

The use of a semantically rich registry containing a Feature Type Catalogue (FTC) to represent the semantics of geographic feature types including operations, attributes and relationships between feature types is required to realise the benefits of Spatial Data Infrastructures (SDIs). Specifically, such information provides a more complete representation of the semantics of the concepts used in the SDI, and enables advanced navigation, discovery and utilisation of discovered resources. The presented approach creates an FTC implementation in which attributes, associations and operations for a given feature type are encapsulated within the FTC, and these conceptual representations are separated from the implementation aspects of the web services that may realise the operations in the FTC. This differs from previous approaches that combine the implementation and conceptual aspects of behaviour in a web service ontology, but separate the behavioural aspects from the static aspects of the semantics of the concept or feature type. These principles are demonstrated by the implementation of such a registry using open standards. The ebXML Registry Information Model (ebRIM) was used to incorporate the FTC described in ISO 19110 by extending the Open Geospatial Consortium ebRIM Profile for the Web Catalogue Service (CSW) and adding a number of stored queries to allow the FTC component of the standards‐compliant registry to be interrogated. The registry was populated with feature types from the marine domain, incorporating objects that conform to both the object and field views of the world. The implemented registry demonstrates the benefits of inheritance of feature type operations, attributes and associations, the ability to navigate around the FTC and the advantages of separating the conceptual from the implementation aspects of the FTC. Further work is required to formalise the model and include axioms to allow enhanced semantic expressiveness and the development of reasoning capabilities.     

三维景观GIS几何建模方法——以无锡唐城为例

本文实现了以 4D测绘数据 (DEM、DOM、DLG、DRG)为基本数据源的无锡唐城古建筑三维数字景观GIS。同时 ,在三维GIS传统三维空间数据模型的基础上 ,提出面向对象的三维建模点对象的划分不同与二维GIS中的点对象 ;针对基于面状的三维GIS,提出有向曲线构建面状复杂单体的几何建模方法是较为简捷的途径。     

Uncertainty analysis of runoff and sedimentation in a forested watershed using sequential uncertainty fitting method

The Soil and Water Assessment Tool(SWAT) was implemented in a small forested watershed of the Soan River Basin in northern Pakistan through application of the sequential uncertainty fitting(SUFI-2) method to investigate the associated uncertainty in runoff and sediment load estimation. The model was calibrated for a 10-year period(1991–2000) with an initial 4-year warm-up period(1987–1990), and was validated for the subsequent 10-year period(2001–2010). The model evaluation indices R~2(the coefficient of determination), NS(the Nash-Sutcliffe efficiency), and PBIAS(percent bias) for stream flows simulation indicated that there was a good agreement between the measured and simulated flows. To assess the uncertainty in the model outputs, p-factor(a 95% prediction uncertainty, 95PPU) and r-factors(average wideness width of the 95 PPU band divided by the standard deviation of the observed values) were taken into account. The 95 PPU band bracketed 72% of the observed data during the calibration and 67% during the validation. The r-factor was 0.81 during the calibration and 0.68 during the validation. For monthly sediment yield, the model evaluation coefficients(R~2 and NS) for the calibration were computed as 0.81 and 0.79, respectively; for validation, they were 0.78 and 0.74, respectively. Meanwhile, the 95 PPU covered more than 60% of the observed sediment data during calibration and validation. Moreover, improved model prediction and parameter estimation were observed with the increased number of iterations. However, the model performance became worse after the fourth iterations due to an unreasonable parameter estimation. Overall results indicated the applicability of the SWAT model with moderate levels of uncertainty during the calibration and high levels during the validation. Thus, this calibrated SWAT model can be used for assessment of water balance components, climate change studies, and land use management practices.     

Measuring urban activities using Foursquare data and network analysis: a case study of Murcia (Spain)

Among social networks, Foursquare is a useful reference for identifying recommendations about local stores, restaurants, malls or other activities in the city. In this article, we consider the question of whether there is a relationship between the data provided by Foursquare regarding users’ tastes and preferences and fieldwork carried out in cities, especially those connected with business and leisure. Murcia was chosen for case study for two reasons: its particular characteristics and the prior knowledge resulting from the fieldwork. Since users of this network establish, what may be called, a ranking of places through their recommendations, we can plot these data with the objective of displaying the characteristics and peculiarities of the network in this city. Fieldwork from the city itself gives us a set of facilities and services observed in the city, which is a physical reality. An analysis of these data using a model based on a network centrality algorithm establishes a classification or ranking of the nodes that form the urban network. We compare the data extracted from the social network with the data collected from the fieldwork, in order to establish the appropriateness in terms of understanding the activity that takes place in this city. Moreover, this comparison allows us to draw conclusions about the degree of similarity between the preferences of Foursquare users and what was obtained through the fieldwork in the city.     

Object-based spatial cluster analysis of urban landscape pattern using nighttime light satellite images: a case study of China

Previous studies have demonstrated urban built-up areas can be derived from nighttime light satellite (DMSP-OLS) images at the national or continent scale. This paper presents a novel object-based method for detecting and characterizing urban spatial clusters from nighttime light satellite images automatically. First, urban built-up areas, derived from the regionally adaptive thresholding of DMSP-OLS nighttime light data, are represented as discrete urban objects. These urban objects are treated as basic spatial units and quantified in terms of geometric and shape attributes and their spatial relationships. Next, a spatial cluster analysis is applied to these basic urban objects to form a higher level of spatial units – urban spatial clusters. The Minimum Spanning Tree (MST) is used to represent spatial proximity relationships among urban objects. An algorithm based on competing propagation of objects is proposed to construct the MST of urban objects. Unlike previous studies, the distance between urban objects (i.e., the boundaries of urban built-up areas) is adopted to quantify the edge weight in MST. A Gestalt Theory-based method is employed to partition the MST of urban objects into urban spatial clusters. The derived urban spatial clusters are geographically delineated through mathematical morphology operation and construction of minimum convex hull. A series of landscape ecologic and statistical attributes are defined and calculated to characterize these clusters. Our method has been successfully applied to the analysis of urban landscape of China at the national level, and a series of urban clusters have been delimited and quantified.