基于对象关系数据库的矢栅一体化查询与操作研究

在分析矢量栅格数据特点的基础上,提出一系列矢栅一体化查询函数,基于PostgreSQL/PostGIS数据库,实现了支持栅格数据存储与组织的扩展数据类型,并对栅格数据类型与PostGIS矢量数据一体化查询函数进行了扩展实现。最后,通过实例验证了矢栅一体化查询函数的表达能力和解决实际问题的应用前景。     

On the accuracy of TIGER-type geocoded address data in relation to cadastral and census areal units

In many applications of Geographical Information Systems (GIS) a common task is the conversion of addresses into grid coordinates. In many countries this is usually accomplished using address range TIGER-type files in conjunction with geocoding packages within a GIS. Improvements in GIS functionality and the storage capacity of large databases mean that the spatial investigation of data at the individual address level is now commonly performed. This process relies on the accuracy of the geocoding mechanism and this paper examines this accuracy in relation to cadastral records and census tracts. Results from a study of over 20 000 addresses in Sydney, Australia, using a TIGER-type geocoding process suggest that 5-7.5% (depending on geocoding method) of addresses may be misallocated to census tracts, and more than 50% may be given coordinates within the land parcel of a different property.     

A GIS-based approach to multiple criteria group decision-making

Abstract

The multiple criteria group decision-making problem involves a set of feasible alternatives that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. This paper is concerned with developing a GIS-based approach to group decision-making under multiple criteria. The approach integrates, within a raster GIS environment, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Borda's choice rule. TOPSIS orders the feasible alternatives according to their closeness to the ideal solution. It is used to derive the individual preference orderings. Borda's method combines the individual preferences into a group preference or consensus/compromise ranking. The approach is implemented within the IDRISI GIS and illustrated on a hypothetical decision situation.     

GIS and remote sensing integration for environmental applications

Abstract

The combined use of remotely-sensed images and vector GIS data has received considerable interest in recent years. This review article discusses the historical move towards closer integration of remote sensing and GIS technologies and the requirements of integrated software systems to enable remotely-sensed data to be combined with vector datasets for maximum effect. The benefits of integration to users of both GIS and remote sensing for environmental applications are reviewed and some thoughts are given on terminology and future directions in this field.     

Parallel polygon line shading: the quest for more computational power from an existing GIS algorithm

Abstract

Utilising the powerful resources of a parallel computer has become a technique available to the GIS software engineer for increasing the performance of such complex software systems. This paper discusses the effectiveness of both automatic and manual parallelising techniques with a view to making an assessment as to whether the inherent sequential structure of GIS software is a detrimental factor inhibiting the use of such techniques. With the aid of the Scan Line Fill (SLF) algorithm in GIMMS, it has been shown that whilst automated parallelization has no merits in this case, a significant performance benefit can be achieved with algorithm redesign at the macro level to exploit the natural geometric parallelism inherent within the algorithm. However, the results illustrate that the full potential of this approach will not be appreciated until the I/O bottleneck is completely overcome, as opposed to merely avoided.     

面向对象整体GIS数据模型的设计与实现

本文在前期GIS概念数据模型研究的基础上 ,提出了面向对象整体GIS数据模型 ,并针对整体GIS软件的实现在系统数据组织、存储结构与访问机制方面进行了较为深入的探讨 ,Deskpro最后简单介绍了基于整体GIS数据模型的商品化软件———SuperMapDeskpro的实现情况     

An Approach to leaching Applied GIS: Implementation for Local Organizations

Abstract

Geographic information systems (GIS) is a fairly new and evolving curriculum area within geography and other disciplines at colleges and universities in the United States. The challenge of teaching underlying concepts of GIS functionality, the details of computer operation and software interfaces, as well as the contexts of various applications can be a difficult one. At Indiana University of Pennsylvania, a teaching strategy—Client-Life Cycle GIS Project Learning—has been introduced in which students in an upper level GIS course work with local organizations, faculty from other university departments, and governmental entities. This allows students with some GIS background to work with real clients; utilize and operationalize the concepts of the GIS Project Life Cycle; make the connection between data development, analysis, and applications development; provide expertise and needed data to local organizations; and see the utility and impact of their work. A group pilot project from the spring semester of 1998 is discussed to illustrate how students responded to this method of teaching GIS.     

Aspects of the implementation of the GEOVIEW design

Abstract

GEOVIEW, an integrated system, uses relational database technology and a graphics package (Graphical Kernel System) to offer a flexible environment in which to develop applications of geographical information systems (GIS). It has facilities to represent data in different spatial data structures. Data are stored and retrieved efficiently by using variable length raw data. The unified representation offers the benefit of storing entities in a single relation and eases the process of overlaying different entities. GEOVIEW also provides a mechanism for tailoring user interfaces to suit the needs of different applications by means of a facility to generate macros and menus.

Processing requirements for GIS applications can be supported by using tools provided by relational database technology and by graphics packages. High-level language interfaces which can process dynamic statements and bind dynamic variables are needed to develop an efficient database interface module. A graphics segment facility is essential to provide editing functions and to maximize the use of the local processing power of graphics workstations in the graphics interface module. Further improvements in performance can be made by using the array fetch facility and linear keys for spatial searching.     

Weight matrices and spatial autocorrelation statistics using a topological vector data model

Abstract

This paper reports on software to construct alternative weight matrices and to compute spatial autocorrelation statistics, namely the Moran coefficient and the Geary coefficient using Arc/Info’s data structure. As such it is an addition to recent efforts in linking GIS with exploratory spatial data analysis. The software is interfaced with Arc/Info via the Arc Macro Language (AML) so that it can be run in the ARC environment. This allows the user to perform exploratory analysis within GIS which may provide insights in subsequent spatial analysis and modelling.     

Spatial analysis of linguistic data with GIS functions

Abstract

During the 1980s techniques for analysis of geographical patterns have been refined to the point that they may be applied to data from many fields. Quantitative spatial analysis and existing functions available in geographical information systems (GIS) enable computerized implementations of these spatial analysis methods. This paper describes the application of quantitative spatial analysis and GIS functions to analysis of language data, using the extensive files of the Linguistic Atlas of the Middle and South Atlantic States (LAMSAS). A brief review of recent development of using quantitative and statistical methods for analysing linguistic data is also included.     

THE ARCHIVES OF THE ASSOCIATION OF AMERICAN GEOGRAPHERS

Although numerous courses in geographic information systems (GIS) have been introduced into the geography curriculum over the past few years, there has been remarkably little debate over the issues involved. This paper first discusses the arguments for geography as an appropriate disciplinary setting for GIS teaching at the undergraduate level. This is followed by a discussion of the nature of GIS courses and their appropriate place in the undergraduate geography curriculum. The final section of the paper describes the NCGIA Core Curriculum project and examines its significance in this broader context.     

Structure and contents of a new geomorphological GIS database linked to a geomorphological map — With an example from Liden, central Sweden

This paper presents the structure and contents of a standardised geomorphological GIS database that stores comprehensive scientific geomorphological data and constitutes the basis for processing and extracting spatial thematic data. The geodatabase contains spatial information on morphography/morphometry, hydrography, lithology, genesis, processes and age. A unique characteristic of the GIS geodatabase is that it is constructed in parallel with a new comprehensive geomorphological mapping system designed with GIS applications in mind. This close coupling enables easy digitalisation of the information from the geomorphological map into the GIS database for use in both scientific and practical applications. The selected platform, in which the geomorphological vector, raster and tabular data are stored, is the ESRI Personal geodatabase. Additional data such as an image of the original geomorphological map, DEMs or aerial orthographic images are also included in the database. The structure of the geomorphological database presented in this paper is exemplified for a study site around Liden, central Sweden.     

Database design for a multi-scale spatial information system

Abstract

Growth in the available quantities of digital geographical data has led to major problems in maintaining and integrating data from multiple sources, required by users at differing levels of generalization. Existing GIS and associated database management systems provide few facilities specifically intended for handling spatial data at multiple scales and require time consuming manual intervention to control update and retain consistency between representations. In this paper the GEODYSSEY conceptual design for a multi-scale, multiple representation spatial database is presented and the results of experimental implementation of several aspects of the design are described. Object-oriented, deductive and procedural programming techniques have been applied in several contexts: automated update software, using probabilistic reasoning; deductive query processing using explicit stored semantic and spatial relations combined with geometric data; multiresolution spatial data access methods combining poini, line, area and surface geometry; and triangulation-based generalization software that detects and resolves topological inconsistency.     

Quadtree storage of vector data†

Abstract

Vector data storage has various advantages in a cartographic or geographical information system (GIS) environment, but lacks internal spatial relationships between individual features. Quadtree structures have been extensively used to store and access raster data. This paper shows how quadtree methods may be adapted for use in spatially indexing vector data. It demonstrates that a vector quadtree stored in floating point representation overcomes the classical problem with raster quadtrees of data approximation. Examples of vector quadtrees applied to realistic size data sets are given     

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.     

Development and application of global databases: considerable progress,but more collaboration needed

Abstract

This paper reviews the development of international collaboration in the availability of global data and processing abilities in the environmental field, beginning in 1957 with tie pioneering activities of the World Data Centres. Considerable progress has been made, particularly through the availability of satellite data, but there are considerable shortcomings in these achievements, arising from the isolated nature of many developments, the difficulties of integrating different sources and weaknesses in the top-down approach. There are now attempts to develop a complementary bottom-up approach, notably through the Global Change Diskette Project Developments in hardware, such as the widespread availability of compatible personal computers operating on MS-DOS and UNIX systems; and easier storage on compact disks, and in software, through access to low-cost and public-domain software such as GRASS and IDRISI, are helping but improved collaboration is needed, in which existing institutions such as the World Data Centers have a major part to play.     

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.     

Paper-Based GIS: A Practical Answer to the Implementation of GIS Education into Resource-Poor Schools in South Africa

Abstract

Geographical information systems (GIS) were phased into the geography curriculum of South African schools from 2006–2008 as part of the National Curriculum Statement (NCS) for grades 10–12. Since its introduction, GIS education in schools across the country has been met with a number of challenges including the cost of purchasing the hardware and software required to elucidate the basic concepts of GIS to learners. This article examines the introduction of GIS education in schools in South Africa. The development and distribution of a paper-based GIS educational package for resource-poor schools in the country is also highlighted. Preliminary educator and learner evaluations of the paper-based GIS package are discussed and the broader learning opportunities and benefits associated with flexible teaching mechanisms are examined.