Showing papers in "Cartographica: The International Journal for Geographic Information and Geovisualization in 1989"

Deconstructing the map

Abstract: The paper draws on ideas in postmodern thinking to redefine the nature of maps as representations of power. The traditional rules of cartography – long rooted in a scientific epistemology of the map as an objective form of knowledge – will first be reviewed as an object of deconstruction. Second, a deconstructionist argument will explore the textuality of maps, including their metaphorical and rhetorical nature. Third, the paper will examine the dimensions both of external power and of the omnipresence of internal power in the cartographic representation of place. Cet article s'aventure dans des concepts post-modernes afin de redefinir la nature des cartes comme etant des representations du pouvoir. Longuement enracinees dans une epistemologie scientifique de la carte comme forme objective de connaissance, les regles traditionnelles de la cartographie seront d'abord revues en tant qu'objets de "deconstruction". Ensuite, les arguments d'un "deconstructioniste" exploreront la "textualite" des cartes, y comp...

The Nature Of Boundaries On ‘Area-Class’ Maps

Abstract: Appropriate generalization methods for geographic data must depend upon the kind of feature being generalized. Most research on cartographic line generalization has concentrated on linear features such as coastlines, rivers and roads; however, methods for the generalization of such linear geographic features may not be appropriate for the generalization of other types of cartographic lines. In this paper, we present a model of another type of cartographic line, namely boundaries between categories or classes which occur over contiguous regions of geographic space. We focus our attention on 'natural' area-class data sets such as soil maps. In the model, such boundary lines are far more similar (mathematically) to elevation contours than they are to coastlines and rivers. Appropriate generalization methods may involve construction of surfaces representing probability of class membership, generalization or smoothing of such surfaces and 'contouring' the probabilities to find boundaries. Pour etre appropriees...

The Integration Of Simplification And Smoothing Algorithms In Line Generalization

Abstract: The cartographic generalization of vector data in digital format involves six distinct processes, including simplification, smoothing, enhancement, displacement, merging, and omission. Although the research agenda has addressed each of the six elements individually, little consideration has been given to the geometric interaction of the components. This paper proposes a conceptual model, based on a sequential set of five procedures – or transformations – for the processing of linear digital data. The geometric interaction of simplification and smoothing algorithms is especially emphasized. The first process involves cleaning the digital file, whereby digitizing errors and duplicate coordinate pairs are eliminated. This is followed by a simple smoothing–normally based on weighted-averaging–designed to eliminate the 'gridding' constraints of the digitizing tablet or other encoding device. A third manipulation involves what is called database simplification where a sequential approach (such as Lang toleranci...

Geographic Logic In Line Generalization

Abstract: The logical problems faced by a geographer who generalizes linear symbols on a map are the same whether traditional or computer methods are used. One must recognize that there are a great many lines on the earth's surface, some of which were created by natural processes while others result from the economic, political or social activities of man. Geographic logic requires that these earth lines, when plotted on a map, should be recognizable representations in terms of symbolization and shape. Furthermore, geographers must understand that the generalization process shortens the length of linear symbols and moves them in geographic space. Critical or characteristic points should be selected so that the flow and position of the line is maintained. Le geographe qui generalise les symboles lineaires d'une carte affronte des problemes logiques identiques, que les methodes, utilisees soient traditionnelles ou automatisees. Nombreuses sont ces lignes qui parcourent la surface du globe : certaines sont issues de p...

Scale-Dependence And Self-Similarity In Cartographic Lines

Abstract: This paper provides a typology of two classes of geometry for cartographic lines, based on the well-known Richardson plots. The first class contains objects having self-similar geometry, features whose structural characteristics are replicated either precisely or statistically with changes in scale. Self-similar features are currently described by fractal models, which some argue are appropriate for all cartographic objects. The fallacy of this statement will be demonstrated. The second class of features is fully scale-dependent, and contains cartographic objects whose geometry varies distinctly with changing scale. Both models are described and applied to examples of digital line features, to demonstrate their worth in encoding and preserving particular types of cartographic detail during automatic generalization. Cet article presente une typologie de deux classes de geometrie de lignes cartographiques, a partir des reputes traces de Richardson. La premiere classe contient des objets qui conservent une g...

CHOROPLETH MAPS ON HIGH RESOLUTION CRTs / THE EFFECTS OF NUMBER OF CLASSES AND HUE ON COMMUNICATION

Abstract: The research reported here was designed to determine how quickly and accurately map readers viewing choropleth maps on a high-resolution computer monitor are able to identify to which class an area...

New projections for world maps / a quantitative perceptive approach

Abstract: The increasing use of maps in mass communication influences to a large extent our concept of geographic space. This is particularly so for world maps. Therefore, the preservation of continental shape should be regarded as an important property of such maps. This paper provides a quantitative measure of continental shape distortion. An operational tool is proposed for the development of world maps that are acceptable from a perceptive point of view but which, at the same time, result from the minimization of an objective distortion criterion. L'usage acru de cartes dans les communications de masse influence en grande partie notre conception de l'espace geographique. Ceci s'applique tout particulierement aux cartes du monde. La preservation de la forme des continents devrait donc etre consideree comme une importante propriete de telles cartes. Cet article presente une mesure quantitative de la distorsion de la forme des continents. On y propose un outil operationnel pour le developpement de cartes du monde ...

Line Generalization Using Spectral Techniques

Abstract: In this paper, a line generalization procedure is presented using filtering techniques and best fitting adjustment with conditions. The series of the original line coordinates is transformed into its slope values counterpart and through Fourier transform the spectrum of the slopes is computed. Applying a digital exponential filter and the inverse Fourier transform the filtered slopes are obtained. The filtered set of the slopes is transformed into a derived smooth line set which is then best fitted into the original line. The best fitting process assures conformality between the original and the derived line; the filter used is automatically selected according to the scales of the original and the derived map. Dans cet article, on presente une procedure de generalisation de ligne qui utilise des techniques de filtrage et des compensations de conformite avec conditions. Les coordonnees de la ligne originale sont transformees en valeurs equivalentes de pente et le spectre des pentes est traite au moyen des ...

Introduction to ‘Numerical Generalization in Cartography’

Abstract: GENERALIZATION In 1907, Dr. Max Eckert read a paper entitled, 'On the Nature of Maps and Map Logic,' before the German Geographical Meeting in Nuremberg. In this seminal paper Eckert identified two types of maps: topographic maps, also called chorographic and survey, and their antithesis, which he termed 'geographically abstract' maps. Geographically abstract maps present, in cartographic form, the results of scientific induction and deduction which includes all general economic, commercial, statistical, ethnographic, population, and physical maps. Eckert also felt these abstract maps, owing to their nature, were usually drawn to small scale. Eckert used this basic classification to discuss the role of 'art' in cartography. Precisely, Eckert stated:

An update to ‘Numerical Map Generalization’

Abstract: Mathematical procedures for the generalization of isarithmic maps are derived. It is shown that the level of generalization for different purposes may be specified in advance, and that under certain conditions the original map can be recreated from the generalized map. Les procedures mathematiques utilisees pour la generalisation des cartes d'isarithmes sont derivees. L'article montre que le niveau de generalisation peut etre specifie a l'avance en fonction des buts vises et que, sous certaines conditions, la carte originale peut etre recree a partir de la carte generalisee.

Interpolated Generalization : Cartographic Theory For Expertguided Feature Displacement

Abstract: Existing small-scale geographic databases may provide useful guidance for automated cartographic generalization. Presumably reflecting geographic wisdom and cartographic skill, a database developed for display at a scale of 1:y should incorporate feature displacements with directional offsets much greater than required for displays at somewhat larger scales. These offsets can direct feature displacement when data developed for display at a comparatively large scale 1:x are to be generalized to 1:z, where 1:x ≯ 1:z ≯ 1:y. A feature displaced for presentation at the intermediate scale 1:z would thus occupy an intermediate position between its representations at 1:x and 1:y. This paper expands these principles through the development of algorithms addressing several aspects of interpolated generalization: displacement of matched endpoints separating geometrically simple feature sections, subsequent displacement of intermediate points in these sections, and simplification and smoothing. Tests based upon a con...

Regionalizing and matching features for interpolated displacement in the automated generalization of digital cartographic databases

Abstract: Expert-guided generalization can be an effective method for generating displaced, simplified and smoothed cartographic lines at a scale between those of a given set of matched large-scale and small-scale representations. Efficient implementation of interpolated generalization can benefit from an automated or semi-automated technique to assist the simultaneous partitioning of the two representations into corresponding sections with matched endpoints. Matched regionalization can take advantage of readily identified intersections of corresponding features. In addition, a measurement template can be useful in identifying exchange crossings of otherwise parallel linear features, such as a highway and railroad that share a transportation corridor. A modified two-scale, two-stage version of the Douglas line-simplification algorithm can first regionalize the small-scale database and then produce a matched regionalization of the large-scale database. These procedures offer developers of cartographic databases an e...

Videodiscs And Surrogate Travel / The Map-Environment Interface

Abstract: The videodisc is the first visual database medium that can provide random access to its contents. As such, it can support simulations that allow a user to control his movement (surrogate travel). In this application, a user is given a map of an area containing a marked course. The user operates a computer to view pictures of the area that have been stored on a videodisc and 'walks' in search of orienteering markers. Using common map use skills such as resection and visual inspection, the user can locate his position on the map and determine that route that will most efficiently locate each marker. Le disque video est le premier support visuel pour base de donnees qui puisse permettre un acces aleatoire a son contenu. Ainsi, il peut supporter des simulations de voyages au cours desquels les usagers ont le controle de leurs mouvements. Dans cette application, on donne a un usager une carte d'une region comprenant un parcours defini. L'usager utilise un ordinateur pour visionner des images de la region deja ...

William borough and the jenkinson map of russia, 1562

Abstract: This paper investigates the provenance of the northern sector of the Jenkinson map of Russia printed by Ortelius in 1570. Scholarly opinion has been notably discordant on its authorship and its relationship to a chart drawn by William Borough of the northern coasts of Russia, whose date has also been disputed. An examination of literary sources, Borough's biography, and the map and chart leads to these conclusions: the northern sector of the map surely was drawn by Borough, it is closely related to Borough's chart, and – contrary to the datings others have assigned the chart – it must have been sketched in 1567– 68. Cet article etudie la provenance du secteur nord de la carte de Russie de Jenkinson, imprimee par Ortelius en 1570. Il y a discordance dans l'opinion des erudits quant a sa paternite et ses relations avec une carte des cotes du nord de la Russie dressee par William Borough, dont la date de parution fait aussi l'objet de disputes. Un examen de la litterature, la biographie de Borough, et des ca...

Do we really know our map users

Abstract: Maps can be produced for many kinds of map users with varying expertise and experiences. Therefore, it would be useful to know who are the users of our maps. This research identified and profiled users of the groundwater maps within the Hydrological Atlas Series of the United States Geological Survey and examined whether differences in users' backgrounds influenced their understanding of the maps. It was found that the principal differences amongst map user backgrounds could be captured by broadly classifying users into two major groups – public and private sector employees. Private sector employees have a technical orientation that enables them to respond well to the technical information presented on these maps while the public sector employees lack such an orientation and thus may experience problems when using the maps. On peut produire des cartes pour divers usagers, d'expertise et d'experience variees. Il serait donc utile de savoir qui sont ces usagers de nos cartes. Cette recherche a identifie et ...

Technology And Education In A Developing Country/An Experience Involving Computer-Assisted Cartography And Indonesia

Abstract: In 1983 the Midwest Universities Consortium for International Affairs (MUCIA) entered into an agreement with the Ministry of Education of the Government of Indonesia to implement World Bank Education Project IX. A major activity of the project was to bring consultants to three Indonesian universities in fields identified by the universities. One of these fields was computer-assisted cartography by the Facultas Geografi of Universitas Gadjah Mada (UGM). The position at Universitas Gadjah Mada was filled in sequence by two consultants including the author who spent from January to August 1987 in Jogyakarta. This paper discusses some of the problems and successes with acquiring, developing, converting and implementing software and a system for teaching. En 1983, le 'Midwest Universities Consortium for International Affairs' a conclu une entente avec le Ministere de l'education du Gouvernement indonesien afin d'implanter le Projet educatif IX de la Banque mondiale. Une part importante de ce projet visait a am...