Showing papers in "Cartographic Journal in 1983"

Satellite Imagery as an Aid to Bathymetric Charting in the Red Sea

Abstract: Bathymetric (water depth) information in some circumstances be obtained from Landsat MSS imagery, especially in bands 4 and 5. The techniques, described by others, normally make use of local information, such as the attenuation coefficient of light in sea water, obtained at the region being examined.This paper describes a relatively simple method for obtaining depth contours. For regions which have not been extensively surveyed but for which a small amount of depth information has been obtained by conventional means, these contours can provide a useful supplement, providing information economically over a wide area. The technique is applied here to a region at the northern end of the Red Sea.

Computerised Land Use Suitability Mapping

Abstract: Land use suitability mapping is a technique which can help find the best location for a variety of developmental actions given a set of goals and other criteria. The mapping technique is based on natural and human processes and analyses the interactions among three sets of factors: location, development actions, and environmental effects. The technique can yield three types of maps: a map showing what land use will cause the least change in environmental processes, a map showing qualitative predictions of environmental impacts of proposed developments, and given certain developmental actions to be carried out and specific environmental actions to be controlled, a map showing the most and least suitable locations for those actions. Two case studies are given in which suitability mapping was used as a tool to help local, state, and federal agencies formulate public policy regarding land use decisions in coastal Southern California.

Digital Terrain Models and their Cartographic and Cartometric Utilisation

Abstract: The article discusses the various types of surveyed digital terrain models the points of which are assumed to describe a surface approximating the true earth surface; these models being differentiated by the surveying process only. The suitability of the various model types as an input for computer assisted cartographic utilisation is discussed and judged from the point of view of a relief cartographer with a geodetic, photogrammetric and geomorphological background. The pure mathematical analysis of digital terrain models is rejected in principle and a spatially-geometrical approach recommended. The necessity for mathematical interpolation of secondary DTMs based on surveyed values as input for computer assisted cartographic products is doubted and the opinion is expressed that cartographic and/or cartometric evaluation should be based directly on the approximation surface described by the surveyed values irrespective of the geometric disposition.

Aesthetic Preferences for the Proportions and Forms of Graticules

Abstract: In addition to their mathematical and cartographic characteristics, earth graticules can be viewed as simple geometric forms having certain properties of shape, proportion, size, and texture. Results of many studies in experimental aesthetics suggest that the proportion of 1:1.6, the golden proportion, may have special universal appeal. A paired comparison experiment was conducted to determine whether people have any consistent preferences for the proportions and shapes of graticules. Elliptical and rectangular figures which ranged in proportion from 1:1.0 to 1:2.5 were used. A strong preference was found for ellipses over rectangles, but there was not evidence of a 'golden graticule' in the proportion of 1:1.6. Rather, more compact dimensions were preferred in both types of figures.

Problem Solving on Maps—the Importance of User Strategies

Abstract: An increasing proportion of cartographic research is directed at the responses of the map user, but little is known, of the methods employed to arrive at those responses. Reports from test subjects required to solve a cartographic problem indicate that they had evolved a variety of strategies to assist them in task solution. The varying nature of those strategies is shown to have a pronounced impact upon the level of subject performance. It is suggested that knowledge of the methods devised by relatively inexperienced subjects to solve map problems should be of concern both to those involved in map design and in the instruction of map users.

An Evaluation of the Use of Grid Squares in Computerised Choropleth Maps

Abstract: There are numerous computer programs to produce choropleth maps and some work has also been published on the use of a grid matrix as a way of dividing an area into discrete units. The purpose of this paper is to combine the two approaches and evaluate the suitability of using a network of grid cells, each containing a representative value of the variable being mapped, as a way of producing choropleth maps on a computer.

Sources for Relief Representation Techniques

Abstract: A wide variety of cartographic procedures may be used to represent various aspects of the earth's surface forms. Some of those procedures, however, are rarely used and apparently unfamiliar to many cartographers. The present compendium of techniques may be used as a resource document by which cartographers can quickly become aware of a wide variety of procedures and find references that may be used to obtain more information about them.

Stereoscopic Coral Maps from Underwater Photogrammetry

Abstract: A block of 360 overlapping photographs were taken underwater with a Nikonos III 35 mm camera fitted with a wide angle 15 mm Nikkor lens. The photographs cover a sloping area, 40 metres by 10 metres, on Broadhurst Reef (Queensland) from a depth of 2.7 metres to 26.2 metres. Ninety-nine steel pegs were surveyed and used as ground control stations for the subsequent photogrammetric adjustment. The collinearity equations of analytical photogrammetry were used to extract three-dimensional co-ordinates for the coral colonies. Two hundred of the coral colonies shown on the photographs were chosen for depiction in map form. Stereoscopic maps were constructed to illustrate the spatial relationship of the coral colonies.

Toward an understanding of scale and its relevance to cartographic communication

Abstract: The content of this paper is to express the concept of scale in a more precise mathematical statement rather than simply a ratio of dimensions on a map to the actual dimensions the map represents. While all cartographers can benefit from new perspectives on an old topic, the paper is directed to new students of cartography who need a methodology for their studies, of which scale will play a very important part.

Photographic, Polyfocal and Polar-Diagrammatic Mapping of Atmospheric Pollution

Abstract: In order to display, predict and combat atmospheric pollution, suitable graphics should be employed. The author proposes some new methods of representation such as mapping air pollution on an air photograph which is printed through screens proportional to air purity, or using the Polyfocal Projection for mapping airport noise. Polar diagrams are used to depict atmospheric stability states.

The use of Maps: the Topographic and Thematic traditions contrasted

Abstract: This study of the maps used to illustrate printed books on geographical topics shows that the number of such maps per book has substantially increased between A.D. 1500 and 1920, with a shift from simple outlines of land and sea, often borrowed from other sources, to more sophisticated representations of statistics and other distributions, often specially drawn. The printing of maps side by side to illustrate either temporal changes or similarities between distributions is shown to be an ancient practice, recently revived, while differences between authors in temperament and intellectual tradition also influence the maps they use to illustrate their books.

Computer-Assisted Cartography—The Dilemma facing British Producers of derived mapping in the 1980s

Abstract: This article is based upon a paper given to a seminar of the Publisher's Association's Map and Guide Group in November 1981. It examines the dilemma facing British commercial mapping houses in considering computer-assisted cartography and suggests some solutions. The views expressed are the author's own and are not necessarily those of his employers.