The isotropic organization of DEM structure and extraction of valley lines using hexagonal grid

The automatic extraction of valley lines (VLs) from digital elevation models (DEMs) has had a long history in the GIS and hydrology fields. The quality of the extracted results relies on the geometrical shape, spatial tessellation, and placement of the grids in the DEM structure. The traditional DEM structure consists of square grids with an eight‐neighborhood relationship, where there is an inconsistent distance measurement between orthogonal neighborhoods and diagonal neighborhoods. The directional difference results in the extracted VLs by the D8 algorithm not guaranteeing isotropy characteristics. Alternatively, hexagonal grids have been proved to be advantageous over square grids due to their consistent connectivity, isotropy of local neighborhoods, higher symmetry, increased compactness, and more. Considering the merits above, this study develops an approach to VL extraction from DEMs based on hexagonal grids. First, the pre‐process phase contains the depression filling, flow direction calculation, and flow accumulation calculation based on the six‐neighborhood relationship. Then, the flow arcs are connected, followed by estimating the flow direction. Finally, the connected paths are organized into a tree structure. To explore the effectiveness of hexagonal grids, comparative experiments are implemented against traditional DEMs with square grids using three sample regions. By analyzing the results between these two grid structures via visual and quantitative comparison, we conclude that the hexagonal grid structure has an outstanding ability in maintaining the location accuracy and bending characteristics of extracted valley networks. That is to say, the DEM‐derived VLs based on hexagonal grids have better spatial agreement with mapped river systems and lower shape diversion under the same resolution representation. Therefore, the DEMs with hexagonal grids can extract finer valley networks with the same data volume relative to traditional DEM.     

The Development of the Chagas' Online Data Entry System (CODES-GIS)

This article describes a web‐based data entry and GIS‐driven mapping system designed for an ethnographic and entomological survey of Chagas’ disease, an emerging zoonotic disease, and Triatoma dimidiata, a primary vector, in the Los Tuxtlas region of Veracruz, Mexico. To better understand this disease in the region, a collaborative, multi‐disciplinary study was initiated to conduct a spatial investigation of T. dimidiata and a community‐by‐community survey of local perceptions of the disease. In order to facilitate such a collaborative effort the CODES‐GIS was developed. This system allows for (near) real‐time mapping, analyses, disease reporting, and results sharing. CODES‐GIS provides a framework for a research team working in a remote area with limited technology, software, or GIS expertise to benefit from (near) real‐time spatial analyses performed at collaborating institutions. The system is bi‐directional, where field personnel can upload data to the system for field‐based map production. Likewise, laboratory personnel can upload diagnostics data for viewing by field personnel. In this way, the system provides a virtual link between the field and the laboratory to increase the speed at which results are returned to the local community. The CODES‐GIS is described along with a selection of study results.     

三维GIS的数据结构探讨

对二维GIS数据结构的缺陷及建立三维GIS数据结构的紧迫性进行了简单阐述,列举了几种常见的三维GIS数据结构,并探讨了如何使用面向对象的方法来构建三维GIS数据结构,针对三维GIS数据结构研究的大体发展趋势做了进一步的阐述。最后提出了有关三维GIS数据结构设计与数据存储方法的一点建议。     

WaterNet: A GIS Application for the Analysis of Hydrologic Networks Using Vector Spatial Data

Traditionally, stream and sub‐watershed characterization in GIS has been accom‐ plished using a DEM‐based terrain analysis approach; however, there is a large amount of existing vector hydrographic data difficult to accurately reproduce using DEMs. WaterNet is a GIS/hydrologic application for the integration and analysis of stream and sub‐watershed networks in vector format. Even with vector data, hydrologic inconsistencies between streams and sub‐watersheds do exist, and are revealed in the form of streams crossing drainage divides and sub‐watersheds with more than one outlet. WaterNet rectifies these inconsistencies and couples the two datasets. Most algorithms involving traces of dendritic networks employ a form of tree traversal which requires topologic information to be organized into specialized data structures. On the contrary, WaterNet develops topologic relationships from GIS attribute tables, which, in combination with sorting and querying algorithms, make the calculation process efficient and easy to implement. With the topologic relationships of the streams and sub‐watersheds, WaterNet can perform traces to calculate cumulative network parameters, such as flow lengths and drainage areas. WaterNet was applied to the catchment of the Texas Gulf coast for a total of 100 cataloging units (411,603 km²) and 60,145 stream lines (183,228 km).     

The network K‐function in context: examining the effects of network structure on the network K‐function

The flaws of using traditional planar point‐pattern analysis techniques with network constrained points have been thoroughly explored in the literature. Because of this, new network‐based measures have been introduced for their planar analogues, including the network based K‐function. These new measures involve the calculation of network distances between point events rather than traditional Euclidean distances. Some have suggested that the underlying structure of a network, such as whether it includes directional constraints or speed limits, may be considered when applying these methods. How different network structures might affect the results of the network spatial statistics is not well understood. This article examines the results of network K‐functions when taking into consideration network distances for three different types of networks: the original road network, topologically correct networks, and directionally constrained networks. For this aim, four scenarios using road networks from Tampa, Florida and New York City, New York were used to test how network constraints affected the network K‐function. Depending on which network is under consideration, the underlying network structure could impact the interpretation. In particular, directional constraints showed reduced clustering across the different scenarios. Caution should be used when selecting the road network, and constraints, for a network K‐function analysis.     

Discovering Spatial Interaction Communities from Mobile Phone Data

In the age of Big Data, the widespread use of location‐awareness technologies has made it possible to collect spatio‐temporal interaction data for analyzing flow patterns in both physical space and cyberspace. This research attempts to explore and interpret patterns embedded in the network of phone‐call interaction and the network of phone‐users’ movements, by considering the geographical context of mobile phone cells. We adopt an agglomerative clustering algorithm based on a Newman‐Girvan modularity metric and propose an alternative modularity function incorporating a gravity model to discover the clustering structures of spatial‐interaction communities using a mobile phone dataset from one week in a city in China. The results verify the distance decay effect and spatial continuity that control the process of partitioning phone‐call interaction, which indicates that people tend to communicate within a spatial‐proximity community. Furthermore, we discover that a high correlation exists between phone‐users’ movements in physical space and phone‐call interaction in cyberspace. Our approach presents a combined qualitative‐quantitative framework to identify clusters and interaction patterns, and explains how geographical context influences communities of callers and receivers. The findings of this empirical study are valuable for urban structure studies as well as for the detection of communities in spatial networks.     

Usability Issues in Applying Participatory Mapping for Neighborhood Infrastructure Planning

Public participation is required in neighborhood infrastructure planning and problem‐solving. Although Participatory GIS methods are considered important to help urban community groups identify problems and express their needs and concerns, usable means to help groups produce their maps remain difficult to be realised. Further, an effective means to facilitate the integration of government spatial plans and participatory maps also remains unclear. This article addresses usability issues in participatory mapping activities by exploring group collaboration mechanics and accomplishing use assessments. The study aims at testing the usefulness and the impact of participatory mapping for community development. User studies including questionnaire surveys, interviews, group usability testing, scenario assessments, and the scaling‐up activity were executed. Transparent photomaps, Mobile GIS, and a Web map were implemented and assessed in the study area. A use scenario for community and official spatial data integration was also developed. The results of user studies show that the use of transparent photomaps is more effective to complete group tasks to discuss, draw, and annotate their infrastructure problems. For group participants, the transparent maps are more engaging, easy to learn, and more error tolerant than the use of Mobile GIS. A combination use of simple and advanced PGIS methods is necessary to be implemented to reach informed priority‐decision making.     

业务协同视角下基于GIS的“五规融合”平台

以建立统一空间规划体系为目标,近年来全国各地相继开展了多规融合探索。要从根本上解决多规融合问题,核心是要解决多规涉及部门间的业务协同。本文基于业务协同研究,结合珠海市实际,探索提出了“五规融合”数据共享、规划编制协同、项目策划生成等业务协同机制,并以GIS技术为基础,对“五规融合”平台建设的设计思路与功能实现进行了探讨。     

数字社区3维可视化查询系统的设计与实现

虚拟现实（VR）与地理信息系统（GIS）是近几年来测绘领域的研究热 点，3维地理信息系统（3D－GIS）则是两者的应用结合。文中在前人研究成果的基础上，对基于数字社区的3维可视化查询的有关技术进行了探索，同时介绍了数字社区3维可视化查询系统的总体设计思想、系统结构以及功能特点。     

The Implications of Including Women's Daily Lives in a Feminist GIScience

In this paper, we argue that a feminist geographical analysis that examines women as active agents in their daily lives, pays attention to the multiplicity of women's experiences in relational space, and values knowledge for transformative purposes, provides insights as to how GIScience might develop in the near future. We draw upon our research with two different community organizations in North Philadelphia to show how a feminist geographical analysis can shape the conceptualization of a community GIS. We argue that collaborative work with community organizations based on “a view from below” necessitates alternative institutional arrangements while providing rich data to better understand the intersection of daily life and information and communication technologies (ICT) as experienced, in the particular case of our work, by poor women. Our research illustrates that understanding ICT frameworks from the perspective of women and in the context of their daily lives has important implications for GIScience.     

A GIS-based Investigation of Gaming Venue Catchments

Globally, the growth of the gambling industry in recent decades has raised questions about the potential for community costs associated with gambling development. In order to minimise the harms and maximise the gains for local, state and national economies, in many jurisdictions the industry is heavily regulated. Regulators rely upon a wide range of information sources to assist in decision making and are often concerned with issues that have socio‐spatial characteristics. Despite this, there have been few applications of geographical information systems (GIS) to gambling behaviour. This paper trials the use of a GIS‐based approach to investigate one aspect of gambling regulation, namely the spatial characteristics of gaming venue catchments. The research was conducted in a suburban region of Canberra, Australia. The results from the study show that the catchment areas of gaming venues can vary considerably and are more complex than previous studies have suggested. The regulatory implications of the findings are discussed as well as possible avenues for further GIS‐based research into gambling.     

Natural Conversational Interfaces to Geospatial Databases

Natural (spoken) language, combined with gestures and other human modalities, provides a promising alternative for interacting with computers, but such benefit has not been explored for interactions with geographical information systems. This paper presents a conceptual framework for enabling conversational human‐GIS interactions. Conversations with a GIS are modeled as human‐computer collaborative activities within a task domain. We adopt a mental state view of collaboration and discourse and propose a plan‐based computational model for conversational grounding and dialogue generation. At the implementation level, our approach is to introduce a dialogue agent, GeoDialogue, between a user and a geographical information server. GeoDialogue actively recognizes user's information needs, reasons about detailed cartographic and database procedures, and acts cooperatively to assist user's problem solving. GeoDialogue serves as a semantic ‘bridge’ between the human language and the formal language that a GIS understands. The behavior of such dialogue‐assisted human‐GIS interfaces is illustrated through a scenario simulating a session of emergency response during a hurricane event.     

定性GIS研究热点挖掘与分析

为了研究定性GIS的研究进展,该文借助文献计量学方法对在Web of Science库中1994年到2013年间的文献进行了挖掘分析。通过文献分析软件Histcite和Citespace对定性GIS文献的挖掘与分析,发现定性GIS的研究热点主要集中在空间推理及其方法和算法的探讨、空间信息的定性表示等方面。定性GIS在1999年有了突破性的进展,但定性GIS并没有只单纯应用于地理学范畴,而是在随后的发展中,较多地应用在社会科学和自然科学等领域。     

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.     

GIS网络的TDN结构表示

分析了GIS网络的基本要素和网络关系，提出了完备表达网络的TDN数据结构，从时间和空间效率上进行了推演，并以试验验证了该结构的实用性。     

Opportunities and Impediments for Open GIS

The field of GIS (S for Systems, Sciences, Services, and Studies) is at a cross‐road in the early 2010s. Aiming to link the multiple visions for the next phase of GIS development, this article suggests that the emerging open GIS should serve as a guiding concept. Contextualized in the broader literature of open science, this article proposes open GIS should include eight dimensions related to data, software, hardware, standards, research, publication, funding, and education. For the GIS community, open GIS offers four exciting opportunities: (1) technology‐driven opportunities for addressing challenges posed by the (spatial) big data deluge; (2) application‐led opportunities for confronting the problems of a rapidly changing planet; (3) curiosity‐inspired, crowd‐powered opportunities for the development of an open and geographic citizen science; and (4) education‐focused opportunities for implementing the vision of a spatial university. Although there are academic, legal, social/political, and environmental impediments for the practice of open GIS, open GIS will become increasingly important in shaping our research and educational agendas in the future.     

基于GIS操作驱动的同步协同显示研究

在同步协同GIS中,GIS图形显示的同步是一个比较重要的问题。本文针对GIS图形操作的特点,分析和研究用XML对GIS图形操作进行描述;研究GIS图形操作封装的基本原理,实现GIS图形操作的封装;根据GIS图形操作封装的结构研究GIS图形操作解析方法,实现GIS图形操作的解析。     

Optimal Stopping Location of a High Speed Train using GIS and Multicriteria Decision‐making

This article develops a methodology using a Geographical Information System (GIS) to evaluate the best location to stop a high speed passenger train when faced with an undesired event. The proposed method is based on multicriteria decision‐making where different stretches of line which could be chosen as the stopping point are ranked depending on the characteristics of the line, the surrounding area and its accessibility for equipment. The method was integrated into the GIS to develop an expert support system for decision makers faced with different kinds of undesired events. It has been applied to a case study on the high speed line between Valladolid and Madrid (Spain). The proposed method is new and has not previously been applied to high speed railway networks and could be adapted to other case studies. The speed of the algorithm provides an almost instantaneous reply within seconds of an emergency situation occurring. The method can therefore be part of an overall support system for decision making in undesired rail events.     

Extending the Qualitative Capabilities of GIS: Computer-Aided Qualitative GIS

A number of approaches for integrating GIS and qualitative research have emerged in recent years, as part of a resurgence of interest in mixed methods research in geography. These efforts to integrate qualitative data and qualitative analysis techniques complement a longstanding focus in GIScience upon ways of handling qualitative forms of spatial data and reasoning in digital environments, and extend engagements with 'the qualitative' in GIScience to include discussions of research methodologies. This article contributes to these emerging qualitative GIS methodologies by describing the structures and functions of 'computer-aided qualitative GIS' (CAQ-GIS), an approach for storing and analyzing qualitative, quantitative, and geovisual data in both GIS and computer aided data analysis software. CAQ-GIS uses modified structures from conventional desktop GIS to support storage of qualitative data and analytical codes, together with a parallel coding and analysis process carried out with GIS and a computer-aided data analysis software package. The inductive mixed methods analysis potential of CAQ-GIS is demonstrated with examples from research on children's urban geographies.