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1.
ABSTRACT

Geospatial data conflation is aimed at matching counterpart features from two or more data sources in order to combine and better utilize information in the data. Due to the importance of conflation in spatial analysis, different approaches to the conflation problem have been proposed ranging from simple buffer-based methods to probability and optimization based models. In this paper, I propose a formal framework for conflation that integrates two powerful tools of geospatial computation: optimization and relational databases. I discuss the connection between the relational database theory and conflation, and demonstrate how the conflation process can be formulated and carried out in standard relational databases. I also propose a set of new optimization models that can be used inside relational databases to solve the conflation problem. The optimization models are based on the minimum cost circulation problem in operations research (also known as the network flow problem), which generalizes existing optimal conflation models that are primarily based on the assignment problem. Using comparable datasets, computational experiments show that the proposed conflation method is effective and outperforms existing optimal conflation models by a large margin. Given its generality, the new method may be applicable to other data types and conflation problems.  相似文献   

2.
The purpose of object matching in conflation is to identify corresponding objects in different data sets that represent the same real-world entity. This article presents an improved linear object matching approach, named the optimization and iterative logistic regression matching (OILRM) method, which combines the optimization model and logistic regression model to obtain a better matching result by detecting incorrect matches and missed matches that are included in the result obtained from the optimization (Opt) method for object matching in conflation. The implementation of the proposed OILRM method was demonstrated in a comprehensive case study of Shanghai, China. The experimental results showed the following. (1) The Opt method can determine most of the optimal one-to-one matching pairs under the condition of minimizing the total distance of all matching pairs without setting empirical thresholds. However, the matching accuracy and recall need to be further improved. (2) The proposed OILRM method can detect incorrect matches and missed matches and resolve the issues of one-to-many and many-to-many matching relationships with a higher matching recall. (3) In the case where the source data sets become more complicated, the matching accuracy and recall based on the proposed OILRM method are much better than those based on the Opt method.  相似文献   

3.
Linear feature matching is one of the crucial components for data conflation that sees its usefulness in updating existing data through the integration of newer data and in evaluating data accuracy. This article presents a simplified linear feature matching method to conflate historical and current road data. To measure the similarity, the shorter line median Hausdorff distance (SMHD), the absolute value of cosine similarity (aCS) of the weighted linear directional mean values, and topological relationships are adopted. The decision tree analysis is employed to derive thresholds for the SMHD and the aCS. To demonstrate the usefulness of the simple linear feature matching method, four models with incremental configurations are designed and tested: (1) Model 1: one-to-one matching based on the SMHD; (2) Model 2: matching with only the SMHD threshold; (3) Model 3: matching with the SMHD and the aCS thresholds; and (4) Model 4: matching with the SMHD, the aCS, and topological relationships. These experiments suggest that Model 2, which considers only distance, does not provide stable results, while Models 3 and 4, which consider direction and topological relationships, produce stable results with levels of accuracy around 90% and 95%, respectively. The results suggest that the proposed method is simple yet robust for linear feature matching.  相似文献   

4.
Geometric conflation is the process undertaken to modify the coordinates of features in dataset A in order to match corresponding ones in dataset B. The overwhelming majority of the literature considers the use of points as features to define the transformation. In this article we present a procedure to consider one-dimensional curves also, which are commonly available as Global Navigation Satellite System (GNSS) tracks, routes, coastlines, and so on, in order to define the estimate of the displacements to be applied to each object in A. The procedure involves three steps, including the partial matching of corresponding curves, the computation of some analytical expression, and the addition of a correction term in order to satisfy basic cartographic rules. A numerical example is presented.  相似文献   

5.
经济地理学视角下的旅游发展理论演进   总被引：1，自引：0，他引：1  
经济地理学是一门非常活跃和发展演化很快的学科.近30年来,经济地理学的发展演化带动了旅游发展理论的演变.回顾旅游发展理论研究的进展,依次有依附理论、生命周期理论、社区研究方法、福特主义、弹性专业化和全球商品链理论,这些理论在旅游方面的应用和研究,从时间和数量上都明显滞后于生产实践活动,说明旅游研究还处于经济地理学科"边缘化"的地位.在今天经济全球化的背景下,旅游产业在迅猛发展之时,旅游发展理论的建设更应与经济地理学紧密结合,由"边缘"走向"核心".  相似文献   

6.
Dispelling a myth? Second homes in rural Wales   总被引：1，自引：0，他引：1  
Second homes have been a source of considerable controversy in Wales for more than three decades. In this article we argue that they have, in reality, become less important in recent times, with the market contracting during the 1990s and other more fundamental demographic changes and housing pressures coming to the fore. Second homes are a highly localized issue, affecting a minority of communities – though, at times, quite severely. Retirement and other housing pressures, however, bring more significant socio-economic changes and these pressures are all too frequently amplified by a planning system used to restrict housing supply rather than manage growth. This paper has three parts, beginning with a general review of the second home debate followed by an examination of the changing geography of second homes, showing how the distribution of these properties altered during the 1990s and how the market contracted. It ends with a review of secondary data, revealing that second homes are a relatively small component of wider processes affecting rural communities, though extremely significant in some areas.  相似文献   

7.
生态水文学是20世纪90年代兴起的一门研究生态过程和生态格局水文机制的新学科。湖泊湿地作为中国5大类天然湿地类型之一,湖泊湿地生态水文学的研究业已成为生态水文学的研究的一个重要对象和分支,其核心在于研究湖泊湿地生态系统中多时空尺度的水文与生物格局、过程的耦合特征及其相互作用。论文首先概述了湖泊湿地生态水文学的研究进展,包括其基本理论,内涵、外延及其主要研究内容;凝练了湖泊湿地生态水文学研究的方法体系、思路及框架;针对目前湖泊湿地生态水文学研究中存在的问题及薄弱环节,提出了湖泊湿地生态水文学未来研究的发展趋势和亟需加强研究的重点方向。在此基础上,以长江中游的典型通江湖泊湿地——鄱阳湖湿地为例,通过开展的湖泊湿地生态水文过程与模拟研究的典型案例,阐述了鄱阳湖湖泊湿地生态水文过程的变化及其植被响应研究的最新进展和研究成果。论文对于构建涵盖湖泊湿地水资源、湖泊湿地生态景观格局与流域管理、湖泊湿地生物多样性保育以及湿地资源可持续利用与生态管理等方向在内的战略研究体系,完善湿地生态水文研究与流域生态与管理的技术支撑体系具有重要的指导意义和实践价值。  相似文献   

8.
Spatial data infrastructure (SDI) actors have great expectations for the second-generation SDI currently under development. However, SDIs have many implementation problems at different levels that are delaying the development of the SDI framework. The aims of this article are to identify these difficulties, in the literature and based on our own experience, in order to determine how mature and useful the current SDI phenomena are. We can then determine whether a general reconceptualization is necessary or rather a set of technical improvements and good practices needs to be developed before the second-generation SDI is completed. This study is based on the following aspects: metadata about data and services, data models, data download, data and processing services, data portrayal and symbolization, and mass market aspects. This work aims to find an equilibrium between user-focused geoportals and web service interconnection (the user side vs. the server side). These deep reflections are motivated by a use case in the healthcare area in which we employed the Catalan regional SDI. The use case shows that even one of the best regional SDI implementations can fail to provide the required information and processes even when the required data exist. Several previous studies recognize the value of applying Web 2.0 and user participation approaches but few of these studies provide a real implementation. Another objective of this work is to show that it is easy to complement the classical, international standard-based SDI with a participative Web 2.0 approach. To do so, we present a mash-up portal built on top of the Catalan SDI catalogues.  相似文献   

9.
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.  相似文献   

10.
《The Journal of geography》2012,111(8):487-491
Abstract

In recent years it has come to be recognized that the study of hypothetical situations can help to illuminate the operation of processes and facilitate the study of real world situations. The present article focuses upon the economic development problems of an imaginary Caribbean island. The reader is given background information relating to the economic activities on the island of Roja Grande and asked to suggest possible development strategies which will lead to a more diversified economy and higher standards of living. The second half of the article outlines the development strategies suggested by an undergraduate who, under examination conditions, was “invited to offer” solutions to the problems posed.  相似文献   

11.
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12.
大数据时代的空间交互分析方法和应用再论   总被引：10，自引：1，他引：9  
空间交互是理解地表人文过程的重要基础,与空间依赖一起共同体现了地理空间的独特性、关联性以及对嵌入该空间的地理分布格局的影响,具有鲜明的时空属性,因此对于地理学研究具有重要意义。大数据为空间交互研究带来了新的机遇,能够使我们在不同时空尺度感知和观察空间交互模式并对其动态演化特征进行模拟和预测,从而为揭示人类活动规律及区域空间结构提供有力支持。本文在探讨空间交互与地理空间模式关系的基础上,描述了利用地理大数据感知空间交互的方式和定量模型,介绍了空间交互分析方法的研究进展及其在空间规划与交通、公共卫生、旅游等领域的应用情况,并就一些基本问题进行了讨论,以期为大数据支持下空间交互相关研究提供指导。  相似文献   

13.
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.  相似文献   

14.
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15.
This article discusses the challenges of doing fieldwork in an antagonistic context. Such an antagonistic context can emerge when a non‐Muslim researcher conducts fieldwork in a Muslim country that experiences humanitarian intervention and reconstruction efforts after natural disasters or the end of conflict. This particular setting can create a conflation of Islamic and Western (liberal) values while a political settlement is about to be consolidated. The case discussed in this article is located in the province of Aceh in Indonesia, where a political settlement of a conflict which lasted more than 25 years converged with a massive influx of foreign aid for disaster mitigation vis‐à‐vis the desire to apply Islamic Law (shari'a). The combined effects of reconstruction efforts and political and armed conflict, forged a problematic co‐presence of Western and non‐Western values, which affected the relations between the (Western) researcher and (non‐Western) researched by creating tension or even hostility between the two. The article argues that methodological dilemmas stemming from such a setting require a relational approach drawing on empathy, sameness and the personal, thereby taking into account emotions when conducting fieldwork. For this particular case I suggest an approach based on teamwork crossing cultures and gender among the research team members. To deal with constraints in such a setting, the article proposes to contextualize any potential difference between the researcher and researched, and to explore various relational elements drawing on psychoanalytical approaches and/or cross‐cultural positioning through and in teamwork.  相似文献   

16.
While the ocean traditionally has attracted little attention within geography, we are now entering an era when marine research is increasingly technologically feasible and, at the same time, human interactions with ocean-space are ever more intense and complex. In response to these changes, a number of geographers ranging from critical development theorists to scholars of global environmental change to biogeographers have turned their attention to the study of marine areas. This article (and the articles that follow in this focus section) brings the ocean to the attention of human and physical geographers, both as an object of study in its own right and as a space for interpreting global social and physical processes and developing geographic techniques that span the land-sea divide.  相似文献   

17.
ABSTRACT. The Mediterranean has traditionally been approached from a geographical and historical perspective that has collapsed the material and political differences between water and land. This conflation has been instrumental in homogenizing the diversity of this interregional arena and turning it into a geopolitical area. Aquacentric thinking brings such approaches to the Mediterranean into question. Cybertheory, which despatializes interaction and helps us think of water as place, is applied to the Mediterranean to bring its multiplicity into dialogue and to explore the possibility of creating a new epistemology of place. Mediter-raneanizing cybertheory introduces diachronicity into theories of simultaneity.  相似文献   

18.
Swidden agriculture is often deemed responsible for deforestation and forest degradation in tropical regions, yet swidden landscapes are commonly not visible on land cover/use maps, making it difficult to prove this assertion. For a future REDD+ scheme, the correct identification of deforestation and forest degradation and linking these processes to land use is crucial. However, it is a key challenge to distinguish degradation and deforestation from temporal vegetation dynamics inherent to swiddening. In this article we present an approach for spatial delineation of swidden systems based on landscape mosaics. Furthermore we introduce a classification for change processes based on the change matrix of these landscape mosaics. Our approach is illustrated by a case study in Viengkham district in northern Laos. Over a 30-year time period the swidden landscapes have increased in extent and they have degraded, shifting from long crop-fallow cycles to short cycles. From 2007 to 2009 degradation within the swidden system accounted for half of all the landscape mosaics change processes. Pioneering shifting cultivation did not prevail. The landscape mosaics approach could be used in a swidden compatible monitoring, reporting and verification (MRV) system of a future REDD+ framework.  相似文献   

19.
多维空间分析的关键技术--空间数据立方体   总被引：9，自引：3，他引：6  
介绍空间数据立方体在“数字城市”建设中的作用以及国内外研究现状;讨论非空间维、空间维、数字度量、空间度量的基本概念和结构,给出空间数据立方体的完整描述。空间数据立方体的分析操作主要由概括分析、局部分析、全局分析和旋转分析组成,介绍这些分析操作的功能和结构;结合具体实例数据介绍多维缓冲区空间分析。  相似文献   

20.
This paper proposes methods for detecting apparent differences between spatial tessellations at two different points in time, with the objective of conflation of spatial tessellations at multiple time points. The methods comprise three steps. First, we eliminate systematic differences between tessellations using the affine transformation. Second, we match subregions between tessellations at two points in time and match boundaries based on matching relationships between the subregions. Third, we propose a distance metric for measuring differences between the matched boundaries and a method for determining whether the measured differences are apparent or not. We apply the proposed methods to a part of the US Census data for 1990 and 2000 and empirically demonstrate the effectiveness of these methods.  相似文献   

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