Cartographic Applications Research Articles

Radar imaging of submarine sand waves in tidal channels

The simple theoretical model of Alpers and Hennings describing the radar imaging of submarine bottom topography in coastal waters with strong unidirectional tidal currents is analytically extended to show the influence of advection. The theory applies for L band radar, where second‐order terms in the hydrodynamic interaction can be neglected as a first approximation. If future imaging radars from satellites and space platforms as the ERS‐I (First European Remote Sensing Satellite), the JERS‐I (First Japanese Earth Remote Sensing Satellite), and the EOS (Earth Observing System) are to be used for cartographic applications, it is necessary to include the effect of advection to improve accuracy. This extension of the model simulates the position of the radar cross‐section modulation relative to coastal geomorphological bedforms. By application of that theory it is possible to map features such as the crests of sandbanks and sand waves.

An assessment of SPOT capability for cartographic applications in Indonesia

Abstract An assessment of the operational cartographic capability of SPOT in Indonesia is presented from the points of view of (1) the size of the smallest distinguishable land cover units through computation of the percentages of pure pixels per unit and dominant unit per pixel and (2) planimetric accuracy. Generally speaking, units larger than 0.16 and 0.05ha can be distinguished with SPOT multispectral (XS) and panchromatic (P) data respectively. For full images, basic manipulations (bilinear transformation or shift, enlargement and rotation) of level-IB SPOT digital data and photographs provide standard deviation accuracies towards local Transverse Mercator (LTM) maps of 2 and 3 pixels, respectively. Due to the poor reliability of most LTM maps, SPOT should undoubtedly be used as a major cartographic data source in Indonesia.

Spaceborne radar imagery — its acquisition, processing and cartographic applications

To date the main cartographic use of spaceborne remote sensing techniques has been through the application of passively sensed data from instruments such as cameras and scanners. In the next few years considerable actively sensed satellite radar coverage of Australia is planned. These satellite systems are to be flexible in terms of varying look angle, differing emitted frequencies and multipolarization. This flexibility should allow acquisition of pseudo multispectral data and improve the information content for cartographic applications. The maximizing of potential benefits from this expected wealth of remotely sensed data will require users to apply the specialized techniques necessary for handling actively sensed imagery. This paper is not a definitive work on radar. Rather, it seeks to stimulate awareness of radar remote sensing by providing an overview of radar systems and the process of data acquisition and imagery formation. The interpretation of radar imagery is also discussed and the variability of the topographic content of radar data is demonstrated.

Investigations of spot cartographic applications in the u.s. geological survey

The U.S. Geological Survey has a longstanding commitment to the advancement of the technology and applications of remotely sensed data from civilian satellite systems. In the past, research based on satellite data was primarily directed toward natural resource and land use applications rather than cartographic applications. The availability of high-resolution, stereoscopic data from the sensors on the Système Probatoire d’Observation de la Terre (SPOT) satellite platform provides new opportunities for cartographic applications. The potential applications include production of satellite image and topographic maps, and generation of digital elevation data. Investigations into these applications of SPOT data were recently initiated by the U.S. Geological Survey.

DISPLACEMENT IN VECTOR-AND RASTER-MODE GRAPHICS

Cartographic generalization often requires the displacement of features from their planimetrically correct positions. Displacement to avoid overlapping symbols, and visual clutter in general, is especially likely when the reduction in scale is substantial. Area generalization, in which the linear boundaries of land-unit or administrative polygons may be eliminated or interrupted, is inherently simpler than the generalization of linear features, such as roads or streams, for which continuity is less readily sacrificed. Either by examining features in isolation or by effecting only a small reduction in scale, attempts to automate cartographic generalization have largely ignored the need to displace line symbols. The few existing attempts to automate displacement suggest that a flexible algorithm able to cope with realistic cartographic applications must treat displacement in two phases: detection and adjustment. A redundant data structure is appropriate, with raster data to detect regions of the map requiring displacement and vector data to shift the features apart.

Réflexions sur l'utilisation à des fins thematiques de l'imagerie satellitaire

The study is concerned with a general model of satellite data interpretation. For this interpretation, the user has to abstract a particular dimension from the landscape considered as a system. A review of some applications in remote sensing has revealed that all the algorithms used in image processing for land surveys consist of operations on three kinds of information extracted from satellite data. In cartographic applications and in land use inventories, the emphasis is laid on the spectral information. When the aim of the study is to model the geographical properties of the landscape, the analysis of spectral information is combined with an analysis of the spatial information. Finally, when evolutionary studies are conducted, the temporal information is introduced.

Remote sensing—Its map output

The use of remotely sensed data for cartographic applications in Australia is rapidly increasing, as is the variety of products produced and the various user groups requiring cartographic output. This paper discusses some of the major cartographic output being produced, particularly products of an ongoing nature.

A Linear View of the World: Strip Maps as a Unique Form of Cartographic Representation

Strip format maps constitute a unique, but often overlooked form of cartographic representation. The purpose of this paper is to combine a historical overview of cartographic applications of the strip format with an evaluation of current implications of continued use of this technique. In addressing these goals, four factors that relate to use or selection of strip maps at various points in history are considered. These include two limiting factors that have at times dictated use of a strip format: map construction materials and the information available to the cartographer. The remaining two factors, map purpose and strategies for cognitive organization of geographic information, are considered as positive factors that have led to strip maps being selected over other map forms. The limiting factors are demonstrated to have been significant primarily in a historical context. Map purpose, on the other hand, appears to be a consistent factor in selection of strip formats throughout history with route follow...

Mapping with micros: teaching introductory computer cartography

Abstract Computer‐assisted cartography has been available for some years on mainframe computers, but programmes have been cumbersome and not readily accessible to undergraduate use. The advent of powerful, stand‐alone microcomputers has changed all this. Cartographic applications can be achieved without high demands in computing skills on the part of the user and, more important, in an interactive environment which allows the user to experiment in ways that are not otherwise possible. Micro‐based cartography offers important educational benefits, not least in developing skills in the decision‐making which underpins graphics communication.

Interactive editing of cartographic raster images

A system for manipulations of binary images is presented. They are generated by segmentation of grey-scale images and stored in a runlength- or quad-tree code. Their standard-size is about 50 million pixels. Besides the raster-to-vector conversion, one main component is a raster-based interactive graphic editor. Handling such large amounts of data fast enough for interactive work on a normal computer (e.g. DEC-VAX) requires specific software solutions. Therefore, a program architecture has been designed to support port asynchronous work on the screen and to update the data on disk. Furthermore, algorithms take advantage of the quad-tree coding and the fact, that the largest part of a cartographic raster image is background. The software is linked to a vector-based graphic information system to meet the requirements of cartographic applications.

Spreads and Chokes: Cartographic Applications and Procedures

Spreads and chokes are common contact-printing procedures utilized in fields peripheral to cartography. Material, equipment, and procedures necessary to replicate the technique are provided for specific applications in production cartography, such as enhanced photomaps and choropleth maps. Several variations of these contacting procedures are possible though each yields different results. The variation most applicable to cartography includes the use of a spacer and diffuser. The amount of spread or choke appropriate to the final product can be determined with a photographic response curve.

Detailed choice of the spectral bands

The SPOT satellite is designed so as to provide multispectral observations with 20 m resolution and panchromatic observation with 10 m resolution. The three spectral bands allow a study of the spectral signature of objects; so, the detailed profile of these bands has been optimized so as to select the parts of major interest in the reflectance of various objects and minimize the atmospheric perturbation in the quantitative measurement. The panchromatic band is mainly involved in cartographic application; so the design of the spectral sensitivity is related to the study of the contrast between objects thematically characterized, taking into account the actual resolution.

The production of orthophotomaps by the random dot technique

This paper explains a process developed by the Royal Australian Survey Corps which gives repeatable and predictable results for the production of orthophotomaps from monochrome photography. Guidelines are given to allow any experienced technician to use the technique for other cartographic applications.

USGS Digital Cartographic Applications Program

The U.S. Geological Survey formed a Digital Applications Team in 1977 and started development of a Digital Cartographic Applications Program. The objectives are to produce, manage, and distribute cartographic data in computer compatible form. The principal types of data are similar in content and accuracy to the categories found on the standard 1:24,000-scale 7.5-minute topographic maps. Activity is also underway to produce a national small-scale data base at 1:2,000,000 scale. The data is organized into a Digital Elevation Model (DEM) data base and a Digital Line Graph (DLG) data base and standard file formats and attribute codes have been developed. The data will become of major importance for map preparation and revision and will allow the development of geographic information systems.

Raster Processing: An Alternative Approach to Automated Cartographic Data Handling

The development of more efficient computer input and output devices adapted to cartographic applications has led to increasingly sophisticated operations being performed on larger and larger volumes of cartographic data. These operations, as well as the storage format of the data, tend to replicate traditional manual methods. However, the range of applications where this approach is cost-effective is rapidly narrowing as more and more data are initially captured in raster format, i.e., in scan lines similar to a television image, rather than feature by feature. In addition, computer storage and processing of raster format data is simpler and more efficient for many applications. Appropriate approaches for automated cartographic processing therefore need to be examined carefully. Many algorithms for processing cartographic data in raster mode already exist. However, before the efficiencies of raster-based processing can be fully realized these algorithms must be tested and extended. Also needed are man-mac...

SUGAR

This paper presents the recently designed interactive computer language for cartography called SUGAR. It is intended for use by non-computer specialists, especially geographers, city planners and landscape architects to make maps by computer. The syntax given is based on English key words with a grammar easily understood by specialists with a non-mathematical background. Different keyword dialects for SUGAR are being designed for different cartographic applications within the basic syntax. A version of SUGAR being implemented is a prototype interpreter for an interactive choropleth mapping program called INPOM. Examples of the graphics capabilities of INPOM are included together with examples of the INPOM dialect of SUGAR. The useability of the language in the batch program environment is discussed as well as directions of further research and implementation.

SUGAR

This paper presents the recently designed interactive computer language for cartography called SUGAR. It is intended for use by non-computer specialists, especially geographers, city planners and landscape architects to make maps by computer. The syntax given is based on English key words with a grammar easily understood by specialists with a non-mathematical background. Different keyword dialects for SUGAR are being designed for different cartographic applications within the basic syntax. A version of SUGAR being implemented is a prototype interpreter for an interactive choropleth mapping program called INPOM. Examples of the graphics capabilities of INPOM are included together with examples of the INPOM dialect of SUGAR. The useability of the language in the batch program environment is discussed as well as directions of further research and implementation.

The Orthophoto and Orthophotomap: Characteristics, Development and Application

Widespread distribution and increasing use of orthophotomaps suggest that all cartographers, whether or not they are involved in their creation, should be familiar with these products. This paper attempts to define the specific elements and capabilities of orthophotography and orthophotomapping. First, the fundamental processes of orthophoto rectification are examined, thus enabling the researcher to recognize both the advantages and limitations of the orthophoto product. Secondly, several cartographic applications of orthophotomapping are examined. These applications are considered with the view that orthophotomapping represents a technique by which spatially arrayed data might be both more accurately measured and communicated because of the special attributes of the orthophotomap, namely, the image of an aerial photograph and the metric qualities of a controlled line map.

Evaluation of the Cartographic Application of ERTS-I Imagery

This paper reports the results of a NASA-sponsored study to examine the overall cartographic potential of ERTS (Earth Resources Technology Satellite). Several specific cartographic experiments by the U.S. Geological Survey (USGS) and a number of other foreign and domestic experiments are analyzed. Additional cartographic applications, such as aeronautical and nautical charting, are also investigated. It is concluded that an ERTS-type satellite has widespread application to a variety of direct mapping tasks-particularly those related to 1:250,000 and smaller-scale mapping. In addition, ERTS imagery indicates areas of change which justify large-scale map revision, and this may be as significant a cartographic application as the direct use of the imagery. By comparing ERTS images of the same area taken one or more years apart or in different seasons, far more cartographic information can be obtained than from the analysis of any single image. This application calls for the continuous operation of an ERTS-type satellite. ERTS is the first system that lends itself to automated mapping from imagery, and this may be the single most important cartographic characteristic of ERTS. As a result of these investigations, it is recommended that ERTS-type satellites be flown continuously for at least a decade. The value of such a program to mankind as a whole in the form of cartographic and related products is believed to outweigh greatly the costs involved. Apparently others join in this view as ERTS-2 was launched on January 22, 1975; at the same time, ERTS-C was authorized and is expected to be launched in 1977 or 1978. Thus, close to a decade of continuous ERTS coverage appears probable.

Digitising of photogrammetric instruments for cartographic applications

In the first part of the paper, an analysis is made of the requirements of the various components of a photogrammetric digitising system designed for cartographic applications. The resolution, density and rate of measurements are established and the various possible measuring devices and systems inspected in terms of their suitability, both for the digitising of purely planimetric detail, e.g., on orthophotographs, and on different types of stereo-plotting machine. The view is also expressed that new stereo-plotters might be devised, which are optimised for digitising rather than for graphical plotting as at present. The second part deals with the operational problems likely to be encountered, including stereo-compilation procedures, recording modes, feature codes, and the relative merits of pre- and post-plotting completion procedures. The possibilities of the on-line connection of stereo-photogrammetric digitising systems to a computer for control and preliminary editing purposes are discussed at some length. Finally some examples of photogrammetric digitising carried out both on experimental and on production bases are described and discussed.