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1.
This article presents two decision support plug‐ins in free GIS software: ArcGIS Explorer Desktop. The ubiquitous WebGIS Analysis Toolkit for Extensive Resources (uWATER) focuses on providing GIS analysis functions: spatial and attribute queries in the public services tool for users with limited access to commercial GIS software. The interface of uWATER is general enough to support decision‐making in numerous management issues in natural resources, economics and agriculture. The uWATER‐Pumping Assessment (uWATER‐PA) toolkit, on the other hand, is an extended package targeting the specific environmental issue of groundwater pumping impacts. The uWATER‐PA package is an excellent alternative to evaluating complex groundwater pumping assessment issues before investing significant time, labor, and funds in monitoring and detailed scientific study. It incorporates simulation of the physics of groundwater flow and user interaction into GIS software. A graphical user interface makes both data entry and interpretation of results intuitive to non‐technical individuals. Results are presented as colored drawdown maps and can be saved in GIS format for future dissemination. The impact of drawdown on existing wells can be characterized and mapped, through the use of uWATER's spatial query capabilities and the drawdown maps generated by uWATER‐PA. 相似文献
2.
An online spatial biodiversity model (SBM) for optimized and automated spatial modelling and analysis of geospatial data is proposed, which is based on web processing service (WPS) and web service orchestration (WSO) in parallel computing environment. The developed model integrates distributed geospatial data in geoscientific processing workflow to compute the algorithms of spatial landscape indices over the web using free and open source software. A case study for Uttarakhand state of India demonstrates the model outputs such as spatial biodiversity disturbance index (SBDI) and spatial biological richness index (SBRI). In order to optimize and automate, an interactive web interface is developed using participatory GIS approaches for implementing fuzzy AHP. In addition, sensitivity analysis and geosimulation experiments are also performed under distributed GIS environment. Results suggest that parallel algorithms in SBM execute faster than sequential algorithms and validation of SBRI with biological diversity shows significant correlation by indicating high R2 values. 相似文献
3.
This paper systematically investigates spatially autocorrelated patterns and the behaviour of their associated test statistic
Moran's I in three bounded regular tessellations. These regular tessellations consist of triangles, squares, and hexagons, each of
increasing size (n=64; 256; 1024). These tesselations can be downloaded at http://geo-www.sbs.ohio-state.edu/faculty/tiefelsdorf/regspastruc/
in several GIS formats. The selection of squares is particularly motivated by their use in raster based GIS and remote sensing.
In contrast, because of topological correspondences, the hexagons serve as excellent proxy tessellations for empirical maps
in vector based GIS. For all three tessellations, the distributional characteristics and the feasibility of the normal approximation
are examined for global Moran's I, Moran's I
(k) associated with higher order spatial lags, and local Moran's I
i. A set of eigenvectors can be generated for each tessellation and their spatial patterns can be mapped. These eigenvectors
can be used as proxy variables to overcome spatial autocorrelation in regression models. The particularities and similarities
in the spatial patterns of these eigenvectors are discussed. The results indicate that [i] the normal approximation for Moran's
I is not always feasible; [ii] the three tessellations induce different distributional characteristics of Moran's I, and [iii] different spatial patterns of eigenvectors are associated with the three tessellations.
Received: 2 July 1999 / Accepted: 9 November 1999 相似文献
4.
This article introduces a software package named GeoSurveillance that combines spatial statistical techniques and GIS routines to perform tests for the detection and monitoring of spatial
clustering. GeoSurveillance provides both retrospective and prospective tests. While retrospective tests are applied to spatial data collected for a
particular point in time, prospective tests attempt to incorporate the dynamic nature of spatial patterns via analyzing time-series
data to detect emergent clusters as quickly as possible. This article will outline the structure of GeoSurveillance as well as describe the statistical cluster detection methods implemented in the software. It concludes with an illustration
of the use of the software to analyze the spatial pattern of low birth weights in Los Angeles County, California.
相似文献
5.
Geographic Information System (GIS) software is constrained, to a greater or lesser extent, by a static world view that is not well-suited to the representation of time (Goodchild 2000). Space Time Intelligence System (STIS) software holds the promise of relaxing some of the technological constraints of spatial only GIS, making possible visualization approaches and analysis methods that are appropriate for temporally dynamic geospatial data. This special issue of the Journal of Geographical Systems describes some recent advances in STIS technology and methods, with an emphasis on applications in public health and spatial epidemiology.The STIS expert workshops were funded in part by grants R01CA092669 and R01CA096002 from the National Cancer Institute, and by grants R43-ES010220 and R44-ES010220 from the National Institute of Environmental Health Sciences. Gillian AvRuskin provided cheerful editorial assistance. We thank the participants at the workshops for providing invaluable expertise and critical insights. 相似文献
6.
7.
Susan P Proctor Sucharita Gopal Asuka Imai Jessica Wolfe David Ozonoff Roberta F White 《Transactions in GIS》2005,9(3):381-396
Spatial autocorrelation analysis was used to identify spatial patterns of 1991 Gulf War (GW) troop locations in relationship to subsequent postwar diagnosis of chronic multisymptom illness (CMI). Criteria for the diagnosis of CMI include reporting from at least two of three symptom clusters: fatigue, musculoskeletal pain, and mood and cognition. A GIS‐based methodology was used to examine associations between potential hazardous exposures or deployment situations and postwar health outcomes using troop location data as a surrogate. GW veterans from the Devens Cohort Study were queried about specific symptoms approximately four years after the 1991 deployment to the Persian Gulf. Global and local statistics were calculated using the Moran's I and G statistics for six selected date periods chosen a priori to mark important GW‐service events or exposure scenarios among 173 members of the cohort. Global Moran's I statistics did not detect global spatial patterns at any of the six specified data periods, thus, indicating there is no significant spatial autocorrelation of locations over the entire Gulf region for veterans meeting criteria for severe postwar CMI. However, when applying local G* and local Moran's I statistics, significant spatial clusters (primarily in the coastal Dammam/Dharhan and the central inland areas of Saudi Arabia) were identified for several of the selected time periods. Further study using GIS techniques, coupled with epidemiological methods, to examine spatial and temporal patterns with larger sample sizes of GW veterans is warranted to ascertain if the observed spatial patterns can be confirmed. 相似文献
8.
9.
Jason K Blackburn rew Curtis Frances Currin Mujica Farrell Jones Patricia Dorn Rosamond Coates 《Transactions in GIS》2008,12(2):249-265
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. 相似文献
10.
This paper shows an explanatory tool (a FORTRAN program linked to GIS software), called VCM (Variable Clumping Method), for
detecting statistically significant `multi-level clumps' in the distribution of points. The multi-level clumps imply a set
of clumps whose clumping radius varies from a small radius to a large radius (in spirits, VCM is similar to the K-function method). Compared with the ordinary (fixed radius) clumping method, VCM can detect overall significant clumps in
the distribution of points.
Received: 8 March 1999/Accepted: 17 September 1999 相似文献
11.
The Likelihood Ratio (LR) Model has been applied as an improvement upon the Frequency Ratio (FR) that computes the ratio of the percentage of the landslide pixels to the percentage of the non-landslide pixels instead of the total number of pixels used in the denominator as in case of the FR. The comparative assessment of the two techniques is made through spatial modelling of GIS vector data using the ArcGIS software. Two different Landslide Information Values were computed for each polygon element of the study area employing the two FR techniques that categorized the study area into five classes of vulnerability using natural breaks (Jenks) technique. Subsequently, vulnerability zonation maps were prepared showing the different levels of landslide vulnerability. The LR technique yielded significantly higher vulnerability assessment accuracy (77%) as compared to the standard FR (71%). 相似文献
12.
A consistent theme in recent work on developing exploratory spatial data analysis (ESDA) has been the importance attached
to visualization techniques, particularly following the pioneering development of packages such as SPIDER and REGARD (Haslett
et al. 1990).
The focus on visual techniques is often justified in two ways: (a) the power of modern graphical interfaces means that graphics
is no longer a way of simply presenting results in the form of maps or graphs, but a tool for the extraction of information
from data; (b) graphical, exploratory methods are felt to be more intuitive for non-specialists to use than methods of numerical
spatial statistics enabling wider participation in the process of getting data insights. However, little work has been done
to decide which visualization tools might be needed to support ESDA, or how they can be most effectively implemented.
This paper briefly reviews a theoretical framework that has been suggested for addressing these issues, which comprises two
elements: firstly a data model, based on the distinction between rough and smooth properties of spatial data, that defines
what an analyst is looking for in data (Haining et al. 1998) and secondly a theoretical model for assessing the quality of
visualisation tools (Cleveland 1994). The emphasis of this paper is the use of the theoretical framework to structure an assessment
of SAGE, a software system that has been written for the spatial statistical analysis (including both exploratory and confirmatory
data analysis) of area based data linked to a GIS. The aim of the assessment is to identify the desirable features of the
system (that might be employed in other systems) whilst also highlighting what the additional requirements are thereby contributing
to the development of systems for ESDA that contain good quality scientific visualization tools for exploratory spatial data
analysis.
Received: 30 September 1998/Accepted: 17 September 1999 相似文献
13.
From fields to objects: A review of geographic boundary analysis 总被引：12，自引：0，他引：12
Geographic boundary analysis is a relatively new approach unfamiliar to many spatial analysts. It is best viewed as a technique
for defining objects – geographic boundaries – on spatial fields, and for evaluating the statistical significance of characteristics
of those boundary objects. This is accomplished using null spatial models representative of the spatial processes expected
in the absence of boundary-generating phenomena. Close ties to the object-field dialectic eminently suit boundary analysis
to GIS data. The majority of existing spatial methods are field-based in that they describe, estimate, or predict how attributes
(variables defining the field) vary through geographic space. Such methods are appropriate for field representations but not
object representations. As the object-field paradigm gains currency in geographic information science, appropriate techniques
for the statistical analysis of objects are required. The methods reviewed in this paper are a promising foundation. Geographic
boundary analysis is clearly a valuable addition to the spatial statistical toolbox.? This paper presents the philosophy of,
and motivations for geographic boundary analysis. It defines commonly used statistics for quantifying boundaries and their
characteristics, as well as simulation procedures for evaluating their significance. We review applications of these techniques,
with the objective of making this promising approach accessible to the GIS-spatial analysis community. We also describe the
implementation of these methods within geographic boundary analysis software: GEM.
Received: 22 March 1999 / Accepted: 7 September 1999 相似文献
14.
15.
Integrating data on health outcomes with methods of disease mapping and spatially explicit models of environmental contaminants are important aspects of environmental health surveillance. In this article, we describe a modular, web‐based spatial analysis system that uses GIS, spatial analysis methods and software services delivered over computer networks to achieve this end. The Environmental Health Surveillance System (EHSS) is a prototype system that is designed to serve three purposes: a secure environment for producing maps of disease outcomes from individual‐level data while preserving privacy; an automated process of linking environmental data, environmental models, and GIS tasks like geocoding for the purposes of estimating individual exposures to environmental contaminants; and mechanisms to visualize the spatial patterns of disease outcomes via Web‐based mapping interfaces and interactive tools like Google Earth. 相似文献
16.
One of the fundamental issues of geographical information science is to design GIS interfaces and functionalities in a way that is easy to understand, teach, and use. Unfortunately, current geographical information systems (including ArcGIS) remains very difficult to use as spatial analysis tools, because they organize and expose functionalities according to GIS data structures and processing algorithms. As a result, GIS interfaces are conceptually confusing, cognitively complex, and semantically disconnected from the way human reason about spatial analytical activities. In this article, we propose an approach that structures GIS analytical functions based on the notion of “analytical intent”. We describe an experiment that replaces ArcGIS desktop interface with a conversational interface, to enable mixed‐initiative user‐system interactions at the level of analytical intentions. We initially focus on the subset of GIS functions that are relevant to “finding what's inside” as described by Mitchell, but the general principles apply to other types of spatial analysis. This work demonstrates the feasibility of delegating some spatial thinking tasks to computational agents, and also raises future research questions that are key to building a better theory of spatial thinking with GIS. 相似文献
17.
Mining Association Rules in Spatio-Temporal Data: An Analysis of Urban Socioeconomic and Land Cover Change 总被引：8，自引：0，他引：8
This research demonstrates the application of association rule mining to spatio‐temporal data. Association rule mining seeks to discover associations among transactions encoded in a database. An association rule takes the form A→B where A (the antecedent) and B (the consequent) are sets of predicates. A spatio‐temporal association rule occurs when there is a spatio‐temporal relationship in the antecedent or consequent of the rule. As a case study, association rule mining is used to explore the spatial and temporal relationships among a set of variables that characterize socioeconomic and land cover change in the Denver, Colorado, USA region from 1970–1990. Geographic Information Systems (GIS)‐based data pre‐processing is used to integrate diverse data sets, extract spatio‐temporal relationships, classify numeric data into ordinal categories, and encode spatio‐temporal relationship data in tabular format for use by conventional (non‐spatio‐temporal) association rule mining software. Multiple level association rule mining is supported by the development of a hierarchical classification scheme (concept hierarchy) for each variable. Further research in spatio‐temporal association rule mining should address issues of data integration, data classification, the representation and calculation of spatial relationships, and strategies for finding ‘interesting’ rules. 相似文献
18.
Geoffrey M. Jacquez 《Journal of Geographical Systems》2000,2(1):91-97
This paper summarizes contributions of GIS in epidemiology, and identifies needs required to support spatial epidemiology
as science. The objective of spatial epidemiology is to identify disease causes and correlates by relating spatial disease
patterns to geographic variation in health risks. GIS supports disease mapping, location analysis, the characterization of
populations, and spatial statistics and modeling. Although laudable, these accomplishments are not sufficient to fully identify
disease causes and correlates. One reason is the failure of present-day GIS to provide tools appropriate for epidemiology.
Two needs are most pressing. First, we must reject the static view: meaningful inference about the causes of disease is impossible
without both spatial and temporal information. Second, we need models that translate space-time data on health outcomes and putative exposures into
epidemiologically meaningful measures. The first need will be met by the design and implementation of space-time information
systems for epidemiology; the second by process-based disease models. 相似文献
19.
通用三维GIS场数据模型研究与实践 总被引：1，自引：0，他引：1
随着三维地理信息系统(geographic information system,GIS)应用的发展,空中电磁信号场、空气与水体污染场、地下地质属性场等连续、非匀质的三维空间属性场数据进行建模、可视化与分析计算对GIS基础软件提出了新的挑战。已被广泛应用的TIN(triangulated irregular network)与栅格数据属于表面模型,通常用来表达二维场数据,其中由TIN组成的封闭表面可用于表达三维体,但两者都无法描述非匀质、连续变化的三维属性场。探讨了在通用GIS基础软件中基于TIN和Grid进行升维表达,实现不规则四面体网格(tetrahedralized irregular mesh,TIM)和体元栅格(voxel grid)两大类三维空间场数据模型,分析了两类数据模型的特点,探讨了三维场数据在可视化和分析计算方面的关键技术,实现了基于TIM与体元栅格表达和应用三维GIS场数据,完善了GIS三维数据模型体系,实现了空/天、地表、地下全空间的一体化表达、模拟与分析计算。 相似文献
20.
针对现有的商业地理信息系统平台难以灵活整合多源影像数据融合使用的问题,深入研究Cesium平台下多种数据源的空间参考差异和瓦片组织规则,针对不同空间参考的瓦片数据源进行混搭设计,提出基于Cesium的多源本地瓦片数据静态和动态加载方案。实验结果表明,单一瓦片数据源加载方案、静态和动态多源瓦片混搭方案的展示效果较好;静态瓦片混搭方案在加载不同空间参考瓦片数据时容易造成变形;动态多源、多空间参考瓦片混搭方案能有效克服变形问题且展示效果佳。本文实现了在开源GIS平台下的多源影像数据的融合使用,为地理信息系统与遥感类项目应用提供了一个低成本、高灵活性的解决方案,具有较为明显的实际应用价值。 相似文献