Date_TXT

Boca Raton, London, New York : CRC press,2004

Cote

526.38 DAL

Auteur

Dal, Peter

Sujet

Geography--Mathematics Geographic information systems

Type de document

Livre

Description :

This book has been written for nonmathematicians who wish to understand some of the assumptions that underlie the manipulation and display of geographic information. It assumes very little basic knowledge of mathematics but moves rapidly through a wide range of data transformations, outlining the techniques involved. Many of these are precise, building logically from certain underlying assumptions; others are based on statistical analysis and the pursuit of the optimum rather than the perfect and definite solution.
Mathematics has its own form of shorthand that often gets in the way of understanding what is going on. For those who are unfamiliar with mathematical notation this can be daunting; but it cannot be avoided. It can in many cases be kept to a minimum and in what follows, the derivation of some of the formulae is placed in boxes that can be digested at leisure without interrupting the narrative. But at the end of the day, compromise has had to be made and as the text progresses there is an increasing use of symbols.
This spirit of compromise is most apparent in the selection of topics discussed. Many things have had to be left out—indeed every chapter could be expanded to a full book and most would require several volumes in order to do their subject justice. Introduction to Mathematical Techniques Used in GIS is therefore a book that allows the reader to get started and then to turn to the many more informative texts that are available.
The text begins with an introduction to geographic data but soon focuses on the "where" rather than the "what." It assumes that the data have been measured and refrains from discussing the techniques of measurement science, other than to recognize that measurement is prone to error. Pure mathematics, even when dealing with vague concepts, provides precise answers that can be verified by anyone. Even statistical analysis uses processes that can be programmed into a computer to give a consistent answer, even when the underlying assumptions are not met or the hypothesis has been incorrectly formulated. The apparent exactness of an answer does not mean that it is correct. To understand the output from, for example, a geographic information system, one needs to understand the quality of the data that are entered into the system, the algorithms behind the data processing, and the limitations of the graphic displays.
This book deals with only part of the bigger picture. It focuses on the basic mathematical techniques, building the whole of mathematics in a series of steps that are the foundations for a deeper understanding. It seeks to lay the foundations for the more complex forms of manipulation that arise in the handling of spatially related data.
The technology behind geographic information systems (GIS) allows such data to be gathered, processed, and displayed. The power and appeal of such systems often lie in their graphical output, the maps that they create. Users of GIS need to understand the quality of that output so that they can advise others on the integrity of their results. The issue is not a matter of which buttons to push but rather of the quality of the information that has been produced. Quality means "fitness for purpose" and "safety in use."