The use of digital map data in the segmentation and classification of remotely-sensed images

Abstract

Remotely-sensed data constitute a major potential source of input to geographical information systems (GIS)However, these data often have a relatively poor classification accuracy compared with that of the cartographic data from maps with which they may be combined in the course of GIS analysis. The possibility exists of using data sets (in the form of digital maps) resident within a GIS in order to improve this accuracy, before the classified image is incorporated into the GIS. Results are discussed from a British Alvey Information Technology project to develop a system for the knowledge-based segmentation and classification of remotely-sensed terrain images, in which the knowledge contained in digital map     

The impact of geographical information systems on the role of spatial data libraries

Abstract

The proliferation of digital cartographic and geographic information technologies has provided an obvious alternative to paper for the storage of maps. Not unlike their paper predecessors, digital maps must be indexed to provide sufficient access points to information and to allow the librarian carto-bibliographic control over the collection. Maps have traditionally been treated as ‘unusual’ books and librarians have relied primarily on cataloguing strategies designed for books. Most automated cataloguing efforts involve nothing more than the computerization of card catalogues without altering the nature and design of the task. This paper examines the utilities and unique qualities of cartographic materials and accounts for deficiencies of traditional cataloguing methods for the handling of both analogue and digital cartographic products. In view of the increased availability of digital cartographic databases, this paper also evaluates requirements and presents issues beyond the conventional responsibilities of spatial data librarianship.     

GIS-cartography: visual decision support for spatio-temporal data handling

Abstract

This paper describes a new joint Dutch research initiative ‘GIS-cartography’, combining the research efforts of the cartographers of Utrecht University, Delft University of Technology and the International Institute for Aerospace Survey and Earth Sciences (ITC) in Enschede. The research initiative focuses on the quantification and visualization of data quality, which will be placed in the context of providing automated visual decision support in specific map use strategies. As these map use strategies can only be performed if the relevant cartographic images can be created, studies of both physical access to the data, user interfaces and the provision of sufficient support to allow the user to understand and to derive sensible conclusions from the data are included in the project. Before modules automatically visualizing data quality can be implemented, data documentation, standardization and integration have to be effected, therefore these issues are also covered.     

Beyond Abstract Map Symbols

Abstract

Crucial aspects of the referent phenomena which provide the subject matter for cartographic symbolism are often overlooked by map interpreters in their haste to “read maps at a glance.” The blame rests largely on those practitioners of the environmental sciences who stress the simple, intuitive nature of maps, while effectively ignoring the true complexity of the cartographic communication process. Those persons who are responsible for traditional map interpretation training programs are also at fault for implying, through long emphasis, that symbol identification, position location, and navigation constitute the essence of map analysis. The intuitive acceptability of map symbols in spite of their abstract character is also a deceptive factor. The fact that there is far “more than meets the eye” to map interpretation is easily demonstrated by looking closely at several basic cartographic symbols. In order to become an effective map user the environmental scientist apparently must go well beyond the mastery of conventional map reading principles and learn to deal with diverse informational dimensions in the context of the map use purpose and the physical/cultural make-up of the geographical region under study.     

Fundamental operations in computer-assisted map analysis

Abstract

Geographical information systems (GIS) provide capabilities for the mapping, management and analysis of cartographic information. Unlike most other disciplines, GIS technology was born from specialized applications. A comprehensive theory relating the various techniques used in these applications is only now emerging. By organizing the set of analytic methods into a mathematical structure, a generalized framework for cartographic modelling is developed. Within this framework, users logically order primitive operators on map variables in a manner analogous to traditional algebra and statistics. This paper describes the fundamental classes of operations used in computer-assisted map analysis. Several of the procedures are demonstrated using a fourth-generation computer language for personal computers.     

Placing dots in dot maps

Dot mapping is a cartographic representation method to visualise discrete absolute values and their spatial distribution. To achieve this, dots equal in size and represented value are used. According to the dot value, a certain number of dots are used to depict a data value. These dots usually form dot clusters. The data value needs to be rounded to a multiple of the dot value. It is possible to roughly determine the visualised data value by counting the dots and multiplying this number with the dot value. As there are many parameters – dot size, dot value, map scale – to consider when designing a dot map, the manual way is very complex and time consuming. This paper presents a method to automatically create a dot representation of a dot map from given statistical data that needs no cartographic expertise. The dot representation may be combined with other elements, such as a topographic background, to form a complete map. So the algorithm can easily be integrated into the map design process. The paper refines the basic approach of automated dot mapping published earlier. The dot placement and arrangement have been improved compared to the basic method.     

Minnesota—A Sketch

Abstract

This article reports the results of an exploratory project to determine the abilities of Grade 6 children to work with digital data. The research questions dealt with understanding what is digital data, understanding what is a pixel, and how digital data can be used, making a digital map, and using pixels to determine area on maps. The results of the project showed that the children in this study were able to work with digital data, and that there is potential for using digital data on the Grade 6 level in geography instruction.     

A Review of: “Applications of Spatial Data Structures: Computer Graphics,Image Processing,and GIS”. By H. SAMET. (Addison-Wesley Publishing Company,Inc, 1989.) [Pp. xv + 507; figures,tables, appendix,references, name and credit index,subject index.] Price US $49.95. ISBN 020150300 X (hardback).

The introduction of automated generalisation procedures in map production systems requires that generalisation systems are capable of processing large amounts of map data in acceptable time and that cartographic quality is similar to traditional map products. With respect to these requirements, we examine two complementary approaches that should improve generalisation systems currently in use by national topographic mapping agencies. Our focus is particularly on self‐evaluating systems, taking as an example those systems that build on the multi‐agent paradigm. The first approach aims to improve the cartographic quality by utilising cartographic expert knowledge relating to spatial context. More specifically, we introduce expert rules for the selection of generalisation operations based on a classification of buildings into five urban structure types, including inner city, urban, suburban, rural, and industrial and commercial areas. The second approach aims to utilise machine learning techniques to extract heuristics that allow us to reduce the search space and hence the time in which a good cartographical solution is reached. Both approaches are tested individually and in combination for the generalisation of buildings from map scale 1:5000 to the target map scale of 1:25 000. Our experiments show improvements in terms of efficiency and effectiveness. We provide evidence that both approaches complement each other and that a combination of expert and machine learnt rules give better results than the individual approaches. Both approaches are sufficiently general to be applicable to other forms of self‐evaluating, constraint‐based systems than multi‐agent systems, and to other feature classes than buildings. Problems have been identified resulting from difficulties to formalise cartographic quality by means of constraints for the control of the generalisation process.     

Map Reading and Abuse

Abstract

The various advantages and limitations of geographical mapping known to map users can be functionally related to the few basic principles which constitute the very nature of the cartographic technique. Numerous map interpretation errors may be traced in large part to a common failure on the part of map users to grasp and effectively deal with these same mapping principles. Since it is possible to identify situations in environmental decision making and planning where the misuse of maps, or outright map reading abuses, could lead to adverse human and environmental impact, the problem is indeed serious. Strategies for minimizing the misuse or abuse of geographical maps appear to rely most heavily on a thorough understanding of basic mapping principles.     

Geographic information systems and the BBC's Domesday interactive videodisk

Abstract

The Domesday Project is an ambitious attempt by BBC Enterprises Ltd to present a contemporary snapshot of the United Kingdom in the 1980s on interactive video disk. Two disks are being produced: the first, the local or community disk, consists essentially of information collected by the British people. The second, the national disk, has (amongst other material) a selection of data from both government and quasi-government sources. In total, the disks will hold about 250 Mb vies of digital data. ;is well as some 50000 photographs and around 20 million words of text. The paper introduces the idea of interactive video and the local disk. It then concentrates on methods of access to, and cartographic display of, data on the national disk. We conclude that it is a significant geographical information system which will ultimately form one of the most widely-used data base systems for the foreseeable future.     

A Review of “Geographies of Media and Communication”

Contemporary cartographic research on mapmaking and map use has a broad mandate and, as a consequence, researchers need a broad suite of methods. Consistent with research developments in other geographic subdisciplines, cartographic researchers now use qualitative methods. They offer the advantage of bringing research closer to the problem-solving realms of mapmakers and map users. Our purpose here is to discuss an array of qualitative methods for mapmaking and map use. Questionnaires, interviews, and protocol methods are used to gather verbal data about mapmaking and map use. Ethnographies produce data from direct observation of mapmakers and users. Maps also are sources for document analysis. We use examples of published cartographic research to elaborate on each of these methods.     

Qualitative Methods for Research on Mapmaking and Map Use

Contemporary cartographic research on mapmaking and map use has a broad mandate and, as a consequence, researchers need a broad suite of methods. Consistent with research developments in other geographic subdisciplines, cartographic researchers now use qualitative methods. They offer the advantage of bringing research closer to the problem‐solving realms of mapmakers and map users. Our purpose here is to discuss an array of qualitative methods for mapmaking and map use. Questionnaires, interviews, and protocol methods are used to gather verbal data about mapmaking and map use. Ethnographies produce data from direct observation of mapmakers and users. Maps also are sources for document analysis. We use examples of published cartographic research to elaborate on each of these methods.     

Tactile-map output from geographical information systems: the challenge and its importance

Abstract

The incorporation of the technology of geographic information systems (GIS) into a wide range of planning decisions makes it important that the visually handicapped have access to GIS-based map products to participate more fully in community decision making. Fortunately, GIS contain many procedures useful to the design of tactile maps, including changes of scale and simplification. Developing research opportunities are outlined within the context of the general problem. Tactile maps using microcapsule paper can be produced quickly, but they must be tested using visually handicapped subjects to ensure that suitable symbolization and specifications are developed.     

Stereoscopic Images From Isoline Maps

Abstract

Beginning students of geography often have difficulty understanding contour and other isoline maps. If the contours can be seen in three dimensions, this concept of surface representation is grasped much more readily. The simplest way for an instructor to demonstrate the isoline concept is to draw stereopair contour images, which, when viewed through a stereoscope, show a three-dimensional surface. Crude, but effective stereocontour maps can be drawn by anyone, regardless of cartographic skill, by using the method outlined in this paper.     

The GEO VIEW design A relational data base approach to geographical data handling

Abstract

Digital map data are currently available based on a variety of data structures, depending on the uses to which the data are to be put Within the major categories of vector and raster data, as well as other structures, there is a multiplicity of data formats. Further to this, data for digital map coordinates are frequently stored in a different way from attribute data pertaining to points, lines and polygons. Given these problems, this paper investigates the possibility of handling different kinds of data structures, as well as both coordinate and attribute information within a unified conceptual scheme. This scheme is expressed in terms of the design of an integrated geographical information system called GEO VIEW, which can be implemented in a relational data base environment. The structure of the tables in the data base is outlined, together with the methodology for coding different kinds of data structure into a standard form. Examples of queries are provided, using the SQL query language, to indicate how the system might be used and problems in optimizing spatial searching on a data base of this kind are addressed.     

Improvement of GIS graphics for analysis and decision-making

Abstract

Current geographical information systems (GIS) include functions to create cartographic output interactively or automatically. However, none of the systems presently incorporates mechanisms to ensure correct application of graphic functions. Many of today's users of GIS are not trained in the design and production of graphics and may create maps that confuse or mislead map users. Poorly-designed maps may obliterate the patterns in displayed information.

This article investigates ways to improve the quality of GIS graphical displays and increase their effectiveness for decision-making. Alternatives are presented for improving map design in GIS, ranging from non-technical efforts to enhancement of software functionality. Suggestions propose augmenting users' abilities to create maps in an automated environment, using an approach termed amplified intelligence: key decisions default explicitly to users, whose knowledge is amplified by a range of high-level tools to carry out map design operations automatically.     

社会地图研究综述与展望

用地图方法研究社会空间已有较长历史,在不同的研究背景下形成了多种研究模式。近年来,大数据的出现和空间信息可视化技术的发展,不仅为社会地图的广泛应用提供了更多数据和方法支撑,也为社会空间的再认识提供了新的契机和可能。本文在对面向社会空间研究的国内外社会地图运用成果进行系统梳理的基础上, 将社会地图的研究应用归纳为要素呈现、问题解释和理论验证3个阶段,并对其具体应用内容、方法和数据形式进行了综述,总结为统计图、点值图、网格图、密度图等四种类型,并就社会地图在中国社会空间研究中的应用可能性及其方向进行了讨论和展望。     

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     

地图符号的语言学机制及其应用研究

分析并总结地图语言学在GIS技术影响下的发展、变化;通过分析当今地图语言的新特点,阐述地图符号的定义;从语言学角度分析地图符号的语言学机制并提出地图符号的语义概念模型。最后简述该模型在地图符号软件中的应用。     

Multicriteria generalization (MCG): a decision-making framework for formalizing multiscale environmental data reduction

Environmental simulation models need automated geographic data reduction methods to optimize the use of high-resolution data in complex environmental models. Advanced map generalization methods have been developed for multiscale geographic data representation. In the case of map generalization, positional, geometric and topological constraints are focused on to improve map legibility and communication of geographic semantics. In the context of environmental modelling, in addition to the spatial criteria, domain criteria and constraints also need to be considered. Currently, due to the absence of domain-specific generalization methods, modellers resort to ad hoc methods of manual digitization or use cartographic methods available in off-the-shelf software. Such manual methods are not feasible solutions when large data sets are to be processed, thus limiting modellers to the single-scale representations. Automated map generalization methods can rarely be used with confidence because simplified data sets may violate domain semantics and may also result in suboptimal model performance. For best modelling results, it is necessary to prioritize domain criteria and constraints during data generalization. Modellers should also be able to automate the generalization techniques and explore the trade-off between model efficiency and model simulation quality for alternative versions of input geographic data at different geographic scales. Based on our long-term research with experts in the analytic element method of groundwater modelling, we developed the multicriteria generalization (MCG) framework as a constraint-based approach to automated geographic data reduction. The MCG framework is based on the spatial multicriteria decision-making paradigm since multiscale data modelling is too complex to be fully automated and should be driven by modellers at each stage. Apart from a detailed discussion of the theoretical aspects of the MCG framework, we discuss two groundwater data modelling experiments that demonstrate how MCG is not just a framework for automated data reduction, but an approach for systematically exploring model performance at multiple geographic scales. Experimental results clearly indicate the benefits of MCG-based data reduction and encourage us to continue expanding the scope of and implement MCG for multiple application domains.