Propagating radial waves of travel cost in a grid

To calculate the minimum cost of travel to each location within a geographical area from a specified set of locations, most geographic information systems represent that area as a rectangular grid of discrete cells, each indicating the cost of traversing that cell's particular location. These increments of cost are then accumulated by proceeding from cell to adjacent cell in a manner that resembles the propagation of waves. Because this propagation is limited to the eight directions associated with each cell's eight neighbors, however, it is often misdirected, and travel costs are therefore often overestimated. This article discusses the context, precedent, design, implementation, performance, and implications of a new algorithm that eliminates such problems in a straightforward manner. It does so by retaining the octangular propagation mechanism of earlier algorithms while keeping track of the particular locations at which propagated waves of accumulating travel cost either refract or diffract. The approach also holds promise for significant improvement in areas ranging from dispersion modeling and shape analysis to interpolation and the delineation of cost-minimizing paths.     

Generalized Mathematical Morphological Method for 3D Shape Analysis of Geological Boundaries: Application in Identifying Mineralization-Associated Shape Features

The shapes of geological boundaries such as contacts and faults play a crucial role in the transportation, deposition and preservation of metals in magmatic and hydrothermal systems. Analyzing the shapes of geological boundaries, in particular those associated with mineralization, is an important step in 3D mineral prospectivity modeling. However, existing methods of shape analysis are limited in the adaptation of various shapes, scales and topologies of geological boundaries. This paper presents a general method of shape analysis based on mathematical morphology (MM), which is a generalization of the original MM method for shape analysis. The generalization extends the applicability of the original MM method from closed surfaces to general surfaces, while inheriting the real 3D and multi-scale analysis capabilities of the original method. This is achieved by regarding MM operations on 3D sphere structural elements as their equivalent operations, and redefining the operations to general surfaces. The generalized MM method enables us to handle complex 3D shapes such as overturned and/or recumbent geological boundaries as well as incomplete shapes due to weathering processes and data unavailability. The proposed method was applied to analyze the shape of an intrusive contact in the Fenghuangshan Cu ore field, Eastern China, whose shape was in the form of a non-closed surface. This analysis revealed a stronger spatial association between the large concave parts of the contact zone and the mineralization. Due to its enhanced adaptability to different shapes, the generalized MM method, compared with the original MM method, allows us to capture shape features that are more plausible for the geological setting.

     

论地理边界的科学属性与表达

地理边界的科学界定体现着对地理对象空间分异规律科学抽象与系统分析的认知水平,是地理学的基础科学问题。本文从地球系统科学的视角,首先阐述了地理边界的基本概念、科学内涵与基本属性等核心概念问题,基于科学性、系统性的基本原则,以内在机理、外在表现以及科学属性等视角为核心依据,对地理边界进行了系统分类。论文分析了地理边界的数学内涵与表达方法,比较了传统地理边界划分法和现代地理边界定量划分方法的特点与差异性,提出了集定性、定量、定位为一体的“地理边界模型”的研究架构。该研究盼在地理边界这个地理学基础理论问题上进行概念辨析与方法分析,丰富地理信息科学的理论与方法。     

From Geographic Holism to Geographic Information System

Substantial changes in a core idea of geography, integration, have occurred since Alexander von Humboldt published Kosmos (1845-1862). These changes are part of a larger shift in Western civilization to mechanistic reasoning. This shift led to the strengthening of system-based analysis, central to the development of geographic information systems (GIS). The duality of holism and the systems approach has led to an apparent contradiction in geography. R. Hartshorne in The Nature of Geography described this contradiction, but as did Alfred Hettner and Emil Wisotzki before, moved to partial systems as the core concept of geographic integration. Hartshorne's concept of vertical integration is the antecedent for the ubiquitous GIS layer model. The reduction of geographic relationships and processes to mechanistic components (layers) aids the systematic approach, but may lessen geographic understanding of a place's interrelationships. Although the partiality of the system approach was already acknowledged by Finch and Hartshorne in the 1930s, the tension between holistic and system approaches in geography remains. Holism and system-based approaches are indeed complementary methods for developing geographic understanding. Using holistic approaches to understand geographic phenomena, before we teleologically (following a purpose) analyze phenomena as a system, extends GIS to include broader interrelationships of geography in specific locations.     

Geo-Narrative: Extending Geographic Information Systems for Narrative Analysis in Qualitative and Mixed-Method Research∗

This research seeks to contribute to advancing qualitative methodologies at the intersection of qualitative geographic information systems (GIS), narrative analysis, 3D GIS-based time-geographic methods, and computer-aided qualitative data analysis. The approach to GIS-based narrative analysis developed in the study, called “geo-narrative,” is based on extending current GIS capabilities for the analysis and interpretation of narrative materials such as oral histories, life histories, and biographies. The three central elements in this approach are (1) narrative analysis as the qualitative approach; (2) 3D GIS-based time-geographic methods as the representational framework; and (3) 3D-VQGIS as the GIS-based computer-aided qualitative data analysis component. A case example based on a study of the lives of the Muslim women in Columbus, Ohio, after 11 September 2001 is used to illustrate the approach.     

From Geographic Holism to Geographic Information System

Substantial changes in a core idea of geography, integration, have occurred since Alexander von Humboldt published Kosmos (1845-1862). These changes are part of a larger shift in Western civilization to mechanistic reasoning. This shift led to the strengthening of system-based analysis, central to the development of geographic information systems (GIS). The duality of holism and the systems approach has led to an apparent contradiction in geography. R. Hartshorne in The Nature of Geography described this contradiction, but as did Alfred Hettner and Emil Wisotzki before, moved to partial systems as the core concept of geographic integration. Hartshorne's concept of vertical integration is the antecedent for the ubiquitous GIS layer model. The reduction of geographic relationships and processes to mechanistic components (layers) aids the systematic approach, but may lessen geographic understanding of a place's interrelationships. Although the partiality of the system approach was already acknowledged by Finch and Hartshorne in the 1930s, the tension between holistic and system approaches in geography remains. Holism and system-based approaches are indeed complementary methods for developing geographic understanding. Using holistic approaches to understand geographic phenomena, before we teleologically (following a purpose) analyze phenomena as a system, extends GIS to include broader interrelationships of geography in specific locations.     

可拓工程方法在自然地理界线划分中的应用

应用可拓工程方法和主成分分析方法,对福建省境内南亚热带北界最佳位置的确定建立了识别对象的物元模型,模型输出的结果获得满意的自然地理意义解释。     

基于GIS的斜坡单元划分方法改进与实现

斜坡单元已广泛应用于滑坡易发性制图和地质灾害评价。然而在山间盆地或大型宽谷处,常规方法划分出的斜坡单元与地貌背景难以匹配。依据高程及其衍生变量的基本形态系统和曲率的流域分割原理,基于ArcGIS技术,通过叠加曲率和反转曲率的流域边界,改进了斜坡单元划分方法。结果表明：与常规方法相比,改进方法不仅能够使用山脊线和山谷线以划分斜坡单元,还能利用台地边界和宽谷边界以分割水平地表与倾斜地表;划分出的单元大小相对均匀,单元形状总体介于圆形和正三角形之间。对于水平成分较多的地区,如黄土塬区和水库库区,该方法与传统方法相比,具有较好的应用前景。     

Using reverse geocoding to identify prominent wildfire evacuation trigger points

Wildfire evacuation trigger points are prominent geographic features (e.g., ridge lines, rivers, and roads) utilized in timing evacuation warnings. When a fire crosses a feature, an evacuation warning is issued to the communities or firefighters in the path of the fire. Current methods for generating trigger buffers have limited utility because the resulting buffers are not explicitly tied to prominent geographic features, making it difficult to visually determine when a fire has breached a trigger point. This work aims to address this limitation by using reverse geocoding to identify prominent geographic trigger points that have more value to emergency managers. The method consists of three steps: 1) generate a trigger buffer using fire-spread modeling; 2) utilize online reverse-geocoding to retrieve geographic features proximal to the buffer boundary; and 3) identify the most prominent geographic features using viewshed analysis and compute the warning time each would offer given predicted fire spread rates to proximal communities. A case study of Julian, California is presented to identify prominent geographic trigger points that may have value to emergency managers in improving the timing of wildfire evacuation warnings in this region.     

Geographies of Displacement: The Karenni and The Shan Across The Myanmar-Thailand Border

First, central to our analysis is the argument that human movement within and across borders fundamentally challenges the view of geopolitics based upon fixed territorial states, inter-state relations, national identities and citizenship; indeed the whole idea of "national geographic". Using the examples of the Karen and Shan peoples, we explore the processes and patterns of forced relocation, displacement and migration in the border regions of Myanmar and Thailand. Our main concern is with forced displacement as a result of political and ethnic conflict; specifically, how the Burmese military regime's desire for "national unity" within Myanmar's "national space" has influenced the militarily inspired displacements of hundreds of thousands of villagers and civilians within the border zones inhabited mostly by so-called "national minorities". We examine the particular problems of the so-called "internally displaced persons" within "national" boundaries compared with the "refugees" and "undocumented migrants" who make it across "international" space into Thailand. We illustrate the ways displaced people are represented by state agencies and the media as "threats" and "transgressors". We consider some of the "long term" aspects of the displacement problem along the Myanmar-Thai border and the vital contribution geographers can make to the study of displacement.     

An automated approach to the classification of the slope units using digital data

Digital elevation and remote sensing data sets contain different, yet complementary, information related to geomorphological features. Digital elevation models (DEMs) represent the topography, or land form, whereas remote sensing data record the reflectance/emittance, or spectral, characteristics of surfaces. Computer analysis of integrated digital data sets can be exploited for geomorphological classification using automated methods developed in the remote sensing community. In the present study, geomorphological classification in a moderate- to high-relief area dominated by slope processes in southwest Yukon Territory, Canada, is performed with a combined set of geomorphometric and spectral variables in a linear discriminant analysis. An automated method was developed to find the boundaries of geomorphological objects and to extract the objects as groups of aggregated pixels. The geomorphological objects selected are slope units, with the boundaries being breaks of slope on two-dimensional downslope profiles. Each slope unit is described by variables summarizing the shape, topographic, and spectral characteristics of the aggregated group of pixels. Overall discrimination accuracy of 90% is achieved for the aggregated slope units in ten classes.     

The Steamer Parish: The Rise and Fall of Missionary Medicine on an African Frontier

In the past decade, the women's employment rate has increased in Gulf Cooperation Council (GCC) states as a result of improved female educational attainment and the expansion of the local market economy. A significant gender gap in labor force participation (LFP) rates has emerged, however, compared to other countries in the Middle East and North Africa. The main aim of this article is to model the spatial variations of female LFP rates across the northeastern part of Oman. A geographically weighted regression (GWR) technique, within the geographic information system platform, is used to address how the relationships between Omani female LFP rates and a set of explanatory variables vary across Omani subnational boundaries. GWR is a powerful approach that can facilitate the identification of areas with lower or higher female LFP rates and help in better understanding the predictors that are associated with women's employment in specific locations. In so doing, this work attempts to fill the gap in the geographic literature regarding the modeling of local spatial patterns of female employment in developing countries. The results show that the female LFP rate is significantly associated with different spatial measures and particularly the geographic distribution of female education. Interestingly, the percentage of female jobs in the public sector is found to have a substantial negative effect on female LFP rates, especially in urban areas. This can be attributed to the propensity of Omani women to work in governmental jobs and reduce their participation in private and other business sectors. The findings of this research analysis not only offer a more nuanced examination of female LFP rate patterns but also provide empirical evidence in support of locally tailored policies pertaining to the female labor force, which might help in increasing women's participation trends in the local economy across local communities.     

An efficient measure of compactness for two-dimensional shapes and its application in regionalization problems

A measure of shape compactness is a numerical quantity representing the degree to which a shape is compact. Ways to provide an accurate measure have been given great attention due to its application in a broad range of GIS problems, such as detecting clustering patterns from remote-sensing images, understanding urban sprawl, and redrawing electoral districts to avoid gerrymandering. In this article, we propose an effective and efficient approach to computing shape compactness based on the moment of inertia (MI), a well-known concept in physics. The mathematical framework and the computer implementation for both raster and vector models are discussed in detail. In addition to computing compactness for a single shape, we propose a computational method that is capable of calculating the variations in compactness as a shape grows or shrinks, which is a typical application found in regionalization problems. We conducted a number of experiments that demonstrate the superiority of the MI over the popular isoperimetric quotient approach in terms of (1) computational efficiency; (2) tolerance of positional uncertainty and irregular boundaries; (3) ability to handle shapes with holes and multiple parts; and (4) applicability and efficacy in districting/zonation/regionalization problems.     

人类命运共同体视域中的国家传统疆域与新疆域

领土疆域是现代国家存在和发展的客观地理空间实体,对国家的长治久安和繁荣稳定具有根本现实意义。在人类社会发展的演进历程中,人类社会共同体在有着固定地理边界的领土上建立了现代国家,然而随着人类探索世界的范围因认知能力、科学技术及经济全球化等变化而扩展,国家地理疆域的形态也由此发生了深刻变化。现代国家的地理疆域已经从领土、近海和近空传统地理空间,向深海、远洋、太空、极地和信息等现代地理空间延展。总的来看,现代国家疆域的形态特征的变化主要表现为,由二维空间向多维空间的变化,从确定性空间向不确定空间延展,从地理空间迈向向利益空间发展,从主权空间向战略空间扩展。在现代国家的地理疆域已经发生变化的前提下,中国在构建人类命运共同体中提出了以和平、主权、普惠、共治为治理原则来治理国际关系新疆域,这不仅为治理国际关系新疆域贡献了中国智慧,也有效推动了中国疆域治理迈向更高台阶。     

Assessing the Accuracy of The Map of the Prefectural Capital of 1261 Using Geographic Information Systems

This paper explores the application of geographic information systems (GIS) in the evaluation of the accuracy of early maps through a case study of The Map of the Prefectural Capital of 1261. The evaluation of the accuracy of early maps is an important aspect of the study of the history of cartography, but no standard methodology has been generally accepted. The purpose of this paper is to assess the positional accuracy and the relative relations of the spatial objects on The Map of the Prefectural Capital using GIS. The procedure of the study includes identification of locations of the points and features of The Map of the Prefectural Capital on a modern base map, digitization of the early map and the modern base map, overlays of the digitized early map and modern base map, and an analysis of the absolute and relative distortion of the early map. The results of the analysis show that The Map of the Prefectural Capital of 1261 is reasonably accurate considering the technical ability of the thirteenth century, although it contains a considerable amount of positional displacement. In contrast to the amount of positional displacement, the relative relations among the objects are depicted much more precisely.     

A framework to enhance semantic flexibility for analysis of distributed phenomena

While some geographic phenomena hold uniform properties, such as land‐use zones, many geographic phenomena are distributed such that their properties vary across an extended area. While such distributed phenomena are best represented as continuous surfaces, individual objects (or features) often emerge among clusters of high or low values in a field. For example, areas of relatively high elevation may be viewed as hills, while flat low‐lying areas are perceived as plains in a terrain. A comprehensive spatial analysis of distributed phenomena should examine both the spatial variance of its attribute surfaces and the characteristics of individual objects embedded in the field. An immediate research challenge to meet such spatial analysis needs is that these emerging features often have vague boundaries that vary according to the use and the user. The nature, and even existence, of these objects depend upon the range of values, or thresholds, used to define them. We propose a representation framework that takes a dual raster‐vector approach to capture both field‐ and object‐like characteristics of distributed phenomena and maintain multiple representations of embedded features delineated by boundaries that are likely to be relevant for the expected uses of the data. We demonstrate how boundaries influence the analysis and understanding of spatiotemporal characteristics of distributed phenomena. Using precipitation as a proof of concept, we show how the proposed framework enhances semantic flexibility in spatiotemporal query and analysis of distributed phenomena in geographic information systems.     

Teaching Geographic Field Methods to Cultural Resource Management Technicians

Abstract

There are perhaps 10,000 technicians in the United States who work in the field known as cultural resource management (CRM). The typical field technician possesses a bachelor's degree in anthropology, geography, or a closely allied discipline. The author's experience has been that few CRM field technicians receive adequate undergraduate training in geographic field methods, such as cartography and orienteering, which are considered critical to the demands of CRM studies. This paper assesses a practical on-the-job-training approach not uncommon to the industry and concludes with a recommended curriculum. As a result, educators should recognize this need as an opportunity to offer courses in basic geographic field methods at the college level.     

基于多重网格求解的土壤属性高精度曲面建模

高精度曲面建模(HASM)是近几年发展起来的可用于地理信息系统和生态建模的一种较高精度的曲面建模方法.本研究选择南方红壤丘陵区江西省吉安市辖区、吉安县和泰和县为研究区,采集150个表层土壤(0～20cm)样品,分别随机选取60、90和120个点作为模拟数据集,90、60和30个点作为验证数据集,基于多重网格(MG)作为...     

Inferring network paths from point observations

The use of geographically referenced point data, such as that obtained from global positioning systems (GPS), is rapidly increasing. However, due to error and uncertainty inherent in most geographic datasets, the ability to accurately associate these point locations with other layers of geographic data is still a challenge. One difficulty in particular is how to associate spatially and temporally referenced point-based observations of a network activity with a network topology such that a continuous network path can be best inferred. In this article, an optimization method for inferring a network path from a temporal sequence of point observations of location is presented. An application to GPS data is provided to highlight various characteristics of the proposed modeling approach relative to several other available techniques.