Establishing a framework for Open Geographic Information science

When conducting research within a framework of Geographic Information Science (GISc), the scientific validity of this work can be argued as highly dependent upon the extent to which the methods employed are reproducible, and that, in the strictest sense, can only be fully achieved by implementing transparent workflows that utilize both open source software and openly available data. After considering the scientific implications of non-reproducible methods, we provide a review of both open source Geographic Information Systems (GIS) and openly available data, before describing an integrated model for Open GISc. We conclude with a critical review of this embryonic paradigm, with directions for future development in supporting spatial data infrastructure.     

Quantifying positional error induced by line simplification

This study examines the effects of line simplification on the positional accuracy of linear features. The goal is to quantify the relation between the level of simplification and the degree of positional error, so that users can choose appropriate levels of simplification that will yield results meeting specific accuracy criteria. The study focuses on the Douglas-Peucker line simplification algorithm and examines both natural and anthropogenic features (streams and roads) derived from United States Geological Survey Digital Line Graphs. Results show that error can be modelled at an aggregate level using cumulative frequency curves and their confidence limits. This makes it possible to identify the level of simplification that eliminates the largest number of vertices while still attaining a specific positional accuracy standard. A simple implementation strategy is described in which an optimal level of simplification is identified and simplification is applied selectively for different lines. The study shows that management of simplification induced error is possible using simple tools well within the reach of GIS users.     

Investigating the Spatiotemporal Links Between Disorder,Crime, and the Fear of Crime

While links between social and physical disorder, crime, and the fear of crime have long been areas of research interest, few studies have looked at these links from a spatiotemporal viewpoint. This is somewhat surprising, as many of the factors associated with disorder, crime, and fear are known to vary over time and space. This paper uses GISystems to investigate potential spatiotemporal links between these areas in Wollongong, New South Wales, with specific focus on links between graffiti and the fear of crime. The results reveal that the distribution of fear of crime varies considerably over time and is often spatially coincident with concentrations of disorder. Graffiti was found to be one of the most prevalent types of physical disorder. The results are discussed in the context of the “broken windows” thesis and strategic intervention at the community level.     

Efficient digitizing through the combination of appropriate hardware and software for error detection and editing

Abstract

Digitizing still remains a major bottle-neck in the creation of geographical data bases. This paper examines procedures and equipment used in the Dane County Land Records Project as a tutorial for others interested in digitizing maps. Topological structure, determined from ‘spaghetti and meatballs’, detects the important errors and provides a basis for efficiency (in time and cost). For manual digitizing, a simple system of capture running on cheap hardware may be as effective as an expensive workstation. Scanning technology, which used to be expensive, has now become practical, as is shown by an experimental scanner used in this project.     

青海旅游资源信息系统设计

应用系统以ArcInfo和ArcView为开发平台 ,以软件工程理论为指导依据 ,应用GIS技术、数据库技术和模块设计技术为基本的技术支持 ,设计了青海旅游信息系统的结构及数据库 ,使用Avenue语言进行二次开发 ,并利用VisualBasic和Flash进行了界面开发及模块实现。该系统可实现青海旅游信息专题图浏览 ,景点查询、定位 ,多媒体方式介绍 ,以及路线选择功能 ,能为游客提供图、文、声并貌的旅游向导 ,实现了青海旅游资源的计算机化宣传 ,也可为GIS技术在青海盐湖资源、水力资源信息技术的应用提供借鉴     

Book Reviews

Abstract

This paper summarizes a research project conducted to investigate the strategies developed by middle school students to solve a route-finding problem using Arc View GIS software. Three different types of route-finding strategies were identified. Some students were visual route-finders and used a highly visual strategy; others were logical route finders and used GIS software tools to apply a more analytical and systematic approach. A third group were transitional route-finders who used an approach that showed evidence of one that was shifting from a visual strategy to one that was more logical. The findings suggest that to be most effective, GIS teaching and curriculum development strategies should begin with an assessment of student understanding of spatial relationships and continue with a progression that spirals according to the evolution of student cognitive mapping skills over time.     

Students’ Perceptions of Their Engagement Using GIS-Story Maps

This article describes the findings of a qualitative phenomenographic study that explored students’ engagement from the perspective of the students. It describes how the participants perceived their engagement when they learned social studies using GIS Story Maps. Qualitative data collection involved classroom observations, student-written reflections, and oral interviews with fourteen eighth-grade student-participants. The data analysis revealed that students perceive Story Maps as engaging in four qualitatively different ways: generating inquiry, visualizing information, mapping interactively, and cycling. Students also see a geographic and cultural connection between Story Maps and their lives, and additional connections beyond the classroom.     

Reflections and speculations on the progress in Geographic Information Systems (GIS): a geographic perspective

Great strides have been made in Geographic Information Systems (GIS) research over the past half-century. However, this progress has created both opportunities and challenges. From a geographic perspective, certain challenges remain, including the modelling of geographic-featured environments with GIS data model, the enhancement of GIS’s analysis functions for comprehensive geographic analysis and achieving human-oriented geographic information presentation. Several basic theoretical and technical ideas that follow the workflow and processes of geographic information induction, geographic scenario modelling, geographic process analysis and geographic environment representation are proposed to fill the gaps between GIS and geography. We also call for designing methods for big geographic data-oriented analysis, making best use of videos and developing virtual geographic scenario-based GIS for further evolution.     

Localized income inequality, concentrated disadvantage and homicide

Several theories (e.g., routine activities, strain and social disorganization theories) suggest that there are effects of income inequality and concentrated disadvantage on crime. This study follows primarily the long line of social disorganization theorizing to explain the intraurban variation of homicide rates in Chicago. In addition to poverty, income inequality adds stress to individuals when they compare their situation to those around them. A localized income inequality (LII) index is implemented in a Geographic Information System (GIS) to measure the inequality between contiguous areas. Defining inequality in a localized context is important because geographic proximity permits close contacts between residents and thus reinforces the awareness of relative deprivation. This inequality index adds a new dimension to concentrated disadvantage in urban areas. The study shows that the new concentrated disadvantage measure is a strong predictor of homicide rates across three areal units of analysis in Chicago, i.e., census tracts, community areas and neighborhood clusters.     

Positional accuracy improvement: a comparative study in Shanghai,China

With the rapid development of geospatial data capture technologies such as the Global Positioning System, more and higher accuracy data are now readily available to upgrade existing spatial datasets having lower accuracy using positional accuracy improvement (PAI) methods. Such methods may not achieve survey-accurate spatial datasets but can contribute to significant improvements in positional accuracy in a cost-effective manner. This article addresses a comparative study on PAI methods with applications to improve the spatial accuracy of the digital cadastral for Shanghai. Four critical issues are investigated: (1) the choice of improvement model in PAI adjustment; five PAI models are presented, namely the translation, scale and translation, similarity, affine, and second-order polynomial models; (2) the choice of estimation method in PAI adjustment; three estimation methods in PAI adjustment are proposed, namely the classical least squares (LS) adjustment, which assumes that only the observation vector contains error, the general least squares (GLS) adjustment, which regards both the ground and map coordinates of control points as observations with errors, and the total least squares (TLS) adjustment, which takes the errors in both the observation vector and the design matrix into account; (3) the impact of the configuration of ground control points (GCPs) on the result of PAI adjustment; 12 scenarios of GCP configurations are tested, including different numbers and distributions of GCPs; and (4) the deformation of geometric shape by the above-mentioned transformation models is presented in terms of area and perimeter.

The empirical experiment results for six test blocks in Shanghai demonstrated the following. (1) The translation model hardly improves the positional accuracy because it accounts only for the shift error within digital datasets. The other four models (i.e., the scale and translation, similarity, affine, and second-order polynomial models) significantly improve the positional accuracy, which is assessed at checkpoints (CKPs) by calculating the difference between the updated coordinates transformed from the map coordinates and the surveyed coordinates. On the basis of the refined Akaike information criterion, the two best optimal transformation models for PAI are determined as the scale and translation and affine transformation models. (2) The weighted sum of square errors obtained using the GLS and TLS methods are much less than those obtained using the classical least squares method. The result indicates that both the GLS and TLS estimation methods can achieve greater reliability and accuracy in PAI adjustment. (3) The configuration of GCPs has a considerable effect on the result of PAI adjustment. Thus, an optimal configuration scheme of GCPs is determined to obtain the highest positional accuracy in the study area. (4) Compared with the deformations of geometric shapes caused by the transformation models, the scale and translation model is found to be the best model for the study area.     

The Implementation and Effectiveness of Geographic Information Systems Technology and Methods in Secondary Education

Abstract

Geographic information systems (GIS) technology and methods have transformed decision-making in society by bringing geographic analysis to the desktop computer. Although some educators consider GIS to be a promising means for implementing reform, it has been adopted by less than 2 percent of American high schools. The reasons behind the interest in GIS, its slow implementation, and its effectiveness in teaching and learning are unclear. To address these concerns, this research describes the extent to which GIS is being implemented in American secondary education and assesses the effectiveness of lessons that use GIS. A survey of 1,520 high schools that own GIS software, along with experiments and case studies in three high schools, provided primary data for assessing the implementation and effectiveness of GIS.     

Travel impedance agreement among online road network data providers

ABSTRACT

Online mapping providers offer unprecedented access to spatial data and analytical tools; however, the number of analytical queries that can be requested is usually limited. As such, Volunteered Geographic Information (VGI) services offer a viable alternative, provided that the quality of the underlying spatialtheir data is adequate. In this paper, we evaluate the agreement in travel impedance between estimates from MapQuest Open, which embraces OpenStreetMap (OSM) data–a is based on VGI datasetfrom OpenStreetMap (OSM), and estimates from two other popular commercial providers, namely Google Maps? and ArcGIS? Online. Our framework is articulated around three components, which simulates potentialcalculates shortest routes, estimates their travel impedance using a routing service Application Program Interface (API), and extracts the average number of contributors for each route. We develop an experimental setup with a simulated dataset for the state of North Carolina. Our results suggest a strong correlation of travel impedance among all three road network providers. and that travel impedanceThe agreement is the greatest in areas with a denser road network and the smallest for routes of shorter distances. Most importantly, tTravel estimates from MapQuest Open are nearly identical to both commercial providers when the average number of OSM contributors along the route is larger. The latter finding contributes to a growing body of literature on Linus’s law, recognizing that a larger group of contributors holds the potential to validate and correct inherent errors to the source dataset.     

Medium and short-term channel planform changes on the Rivers Tay and Tummel, Scotland

Channel planform change was analysed using a variety of data-sources for the medium-term (>25 years and <250 years) and short-term (<25 years) on a reach of the Rivers Tay and Tummel, Scotland. Map data were input into a Geographic Information System (GIS) and used to determine planform characteristics and changes in width, braiding index and sinuosity for the study reach between 1755 and 1976. Aerial photographs were utilised to determine the more recent changes that had taken place between 1971 and 1994. The analysis showed that significant changes had occurred over the medium term with a mean reduction in channel width of 34% for this period. These changes are comparable to those found in studies of similar European rivers for this period. Changes determined for the short-term displayed a continuance of this trend at a comparable rate of change. An analysis of flood frequency and magnitude, precipitation and discharge records for both periods does not show an associated decrease and therefore does not reflect the changes in channel planform. Evidence points towards flood embankment construction in the mid-1800s as the initial cause of channel change for the study reach which was later exacerbated by flow regulation. Incision and the subsequent stabilisation of lateral and mid-channel gravel bars by vegetation succession has resulted in an overall increase in the stability of the study reach which has persisted even where the embankments have fallen into disrepair.     

Prediction of Aquifer Vulnerability to Pesticides Using Fuzzy Rule-Based Models at the Regional Scale

Contamination of ground water has been a major environmental concern in recent years. The potential for ground-water contamination by pesticides depends on porous media, solute, and hydrologic parameters. Although sophisticated deterministic computer models are available for assessing aquifer-contamination potential on a site-by-site basis, most deterministic models are too complex for vulnerability assessment on a regional scale because they require input data that are spatially and temporally variable, and which may not be available at this scale. Therefore, development of an affordable model that is robust under conditions of uncertainty at the watershed scale with minimum input of field data becomes a useful ground-water management tool. The purpose of this study was to examine the usefulness of fuzzy rule-based techniques in predicting aquifer vulnerability to pesticides at the regional scale. The objectives were to (1) develop fuzzy rule-based models using the same input parameters contained in an index-based model (i.e., the modified DRASTIC model), (2) determine the sensitivity of fuzzy rule model predictions, (3) compare the outputs of the fuzzy rule-based models with those of the modified DRASTIC model and with the results of aquifer water-quality analyses, and (4) examine the spatial variability of field parameters around contaminated wells of the Alluvial aquifer in Woodruff County Arkansas. The fuzzy rule-based model for objective (1) was developed using similar parameter weights and ratings as the modified DRASTIC model. For objective (2), fuzzy rule-based models were created using fewer parameters than the modified DRASTIC model. Sensitivity of the fuzzy rule-based models was determined using different combinations of weights of the four input parameters in DRASTIC. It was found that variations in the weights of the input parameters and number of fuzzy sets influenced the location of the aquifer-vulnerability categories as well as the area within each fuzzy category. The fuzzy rule models tended to predict somewhat higher vulnerabilities of the Alluvial aquifer than the modified DRASTIC model. The fuzzy rule base that had the soil-leaching index (S) as the highest weight was chosen as the best fuzzy rule model in predicting potential contamination by pesticides of the aquifer. In general, the fuzzy rule models tended to overestimate the vulnerability of the aquifer in the study area.     

Voronoi tessellation on the ellipsoidal earth for vector data

Voronoi tessellation, and its dual the Delaunay triangulation, provide a cohesive framework for the study and interpretation of phenomena of geographical space in two and three dimensions. The planar and spherical solutions introduce errors in the positional accuracy of both Voronoi vertices and Voronoi edges due to errors in distance computations and the path connecting two locations with planar lines or great circle arcs instead of geodesics. For most geospatial applications the introduction of the above errors is insignificant or tolerable. However, for applications where the accuracy is of utmost importance, the ellipsoidal model of the Earth must be used. Characteristically, the introduction of any positional error in the delimitation of maritime zones and boundaries results in increased maritime space for one state at the expense of another. This is a situation that may, among others, have a serious impact on the financial activities and the relations of the states concerned. In the context of previous work on maritime delimitation we show that the Voronoi diagram constitutes the ideal solution for the development of an automated methodology addressing the problem in its entirety. Due to lack of a vector methodology for the generation of Voronoi diagram on the ellipsoid, the aforementioned solution was constrained by the accuracy of existing approaches. In order to fill this gap, in this paper we deal with the inherent attributes of the ellipsoidal model of the Earth, e.g. the fact that geodesics are open lines, and we elaborate on a methodology for the generation of the Voronoi diagram on the ellipsoid for a set of points in vector format. The resulting Voronoi diagram consists of vertices with positional accuracy that is only bounded by the user needs and edges that are comprised of geodesics densified with vertices equidistant to their generators. Finally, we present the implementation of the proposed algorithm in the Python programming language and the results of two case studies, one on the formation of closest service areas and one on maritime boundaries delimitation, with the positional accuracy set to 1 cm.     

Analysis of positional uncertainty of road networks in volunteered geographic information with a statistically defined buffer-zone method

Volunteered geographic information (VGI) is crowdsourced information that can enrich and enhance research and applications based on geo-referenced data. However, the quality of VGI is of great concern, and positional accuracy is a fundamental basis for the VGI quality assurance. A buffer-zone method can be used for its assessment, but the buffer radius in this technique is subjectively specified; as result, different selections of the buffer radius lead to different positional accuracies. To solve this problem, a statistically defined buffer zone for the positional accuracy assessment in VGI is proposed in this study. To facilitate practical applications, we have also developed an iterative method to obtain a theoretically defined buffer zone. In addition to the positional accuracy assessment, we have derived a measure of positional quality, which comprises the assessment of positional accuracy and the level of confidence in such assessment determined with respect to a statistically defined buffer zone. To illustrate and substantiate the theoretical arguments, both numerical simulations and real-life experiments are performed using OpenStreetMap. The experimental results confirm the high significance of the proposed statistical approach to the buffer zone-based assessment of the positional uncertainty in VGI.     

Spatio-temporal analysis of flowering using LiDAR topography

Spatio-temporal patterns of flowering in forest ecosystems are hard to quantify and monitor. The objectives of this study were to investigate spatio-temporal patterns(e.g. soilssimple slope classesslope aspectand flow accumulation) of flowering around Lake IssaqueenaSouth Carolina(SCUSA) using plant-flowering database collected with GPS- enabled camera(stored in Picasa 3 web albums and project website) on a monthly basis in 2012 and Li DAR-based topography. Pacolet fine sandy loam had the most flowering plantsfollowed by Madison sandy loamboth dominant soil types around the lake. Most flowering plants were on moderately steep(17%–30%) and gently sloping(4%–8%) slopes. Most flowering plants were on west(247.5°–292.5°)southwest(202.5°–247.5°)and northwest(292.5°–337.5°) aspects. Most flowering plants were associated with minimum and maximum flows within the landscape. Chi-square tests indicated differences in the distributions of the proportions of flowering plants were significant by soil typeslopeaspectand flow accumulation for each month(February-November)for all months(overall)and across months. The Chi-square test on area-normalized data indicated significant differences for all months and individual differences by each month with some months not statistically significant. Cluster analysis on flowering counts for nine plant families with the most flowering counts indicated no unique separation by clusterbut implied that the majority of these families were flowering on strongly sloping(9%–16%) slopeson southwest(202.5°–247.5°) aspectsand low flow accumulation(0–200). Presented methodology can serve as a template for future efforts to quantify spatio-temporal patterns of flowering and other phenological events.     

Building Environmental Literacy through Participation in GIS and Multimedia Assisted Field Research

Abstract

A Learning Support System (LSS) that emphasizes experiential research in natural environments using the cutting-edge technologies of GIS and multimedia has been developed for teaching environmental literacy to undergraduate students at the University of Georgia. Computers are used as cognitive tools to create a context in which students become interns in an ecological research center. Students are instructed to conduct research in the form of two field laboratories (the stream and forest laboratories). They accomplish their tasks by collecting data in the field (the State Botanical Garden of Georgia near the campus). They enter the data in the Learning Support System (LSS), and are guided to formulate hypotheses relating to stream water quality and human impact on forest succession for testing. Students also interact with the Environmental Research Support Site (ERSS) within the LSS for explanations to their findings. A specially customized Arc View GIS program within the LSS provides a tool to students for spatial analysis in the case of the forest laboratory. Students and faculty evaluations as well as final examination results confirmed the receptiveness of students to the LSS approach and its effectiveness in the learning of environmental literacy.     

Bank branch closures in New Zealand: the application of a spatial interaction model

Banking is going through a revolution that is radically altering the way banks work and the way customers use them. It is a revolution driven by global competition and enabled by technology. Unlike the back-room developments of previous decades, contemporary restructuring is directly affecting the network of bank branches and opportunities customers have to interact with them. Today virtually all retailing banks are seeking ways of reducing their extensive and costly network of branches and experimenting with alternative means of interacting with customers. Many of the difficulties of deciding what branches to close relate to predicting the impact of such closures on remaining parts of the bank’s network. The aim of this paper is to illustrate the application of a GIS-based spatial interaction model designed to help banks make that decision. Applied in the New Zealand context, it draws attention to some of the opportunities, as well as difficulties, a spatial interaction model creates in assessing the consequences of closing branches, both for the bank itself and for the wider community.