Preface   I have always felt a need to incorporate current information in Geographic Information System (GIS) textbooks. I used to exhort students to make use of the vast resources available on the Web contributed by organizations, Universities, companies, groups, academics, users and a lot of individuals. During my classroom interactions with regular and DDE students, the student community identified three major concerns namely accessibility, comprehension and evaluation of web resources. Most of the students access web from browsing centers that offer access at a price band of Rs 20 to 25 per hour. GIS is about maps and data. Downloading image files take time and this directly translates into extended browsing time and expenses. Secondly, there is a mind-boggling range and depth of information available on GIS. Semantic barriers retard comprehension and dwell time on a particular topic has its impact on time and money budgets. Maintaining a sense of continuity amidst plethora of information is a daunting task. Thirdly, the quality of the web pages range from superb to drab. The site update date and currency of posted information do not match at all times. Entry level users reported difficulties in content evaluation. In the context of access removed from home/workplace, all these factors were found to curb the initiatives of students. A stray thought of preparing a handout for students with annotated information on web sites occurred to me sometime back. Working on the idea, I realized that the sheer number of web sites related to GIS is enough to discourage even the most stubborn. A search string on GIS returned about 1.2 million sites! Even after refining search strings I ended up with thousands of pages. The genuine concerns identified by students were largely applicable to most of us. I promptly discarded the idea of creating a comprehensive guide and embarked upon organizing the collected information as an introductory textbook, the work you have in hand. I admit that I have not authored all that is compiled in this book. I have taken the liberty of using appropriate material from the GIS fraternity to avoid reinventing the wheel. Apart from arriving at the content design, I have edited the information to suit the language skill level of our students. I register my most profound thanks to GIS practitioners who have taken pains to post so much quality information. I still maintain that the best course available to those who can afford is to browse the web and gain information. This book is aimed at the student section who can ill afford such a luxury. I honestly believe that the text is a useful primer to other interested readers as well. I express my profound gratitude and thankfulness to the pro chancellor of Annamalai University Dr. M.A. M. Ramaswamy for the encouragement. I am grateful for the Foreword given by our Vice Chancellor and the permission to publish this book. I am extremely thankful to my department, publisher, colleagues, friends and of course students. I am very grateful for personal encouragement and advice received from Mr.S.Balashanmugam, Secretary to Vice Chancellor, Annamalai university. My special thanks are due to Mr.B.Pavendan for his assistance in content creation and editing, Mr.N.Senthil for the excellent book designing, my friend Mr.N.Prabhakaran, for coordinating this exercise throughout. Several of my friends and guides motivated me to bring out book and I am particularly grateful to Dr.SM.Ramasamy, Director, Centre for Remote Sensing, Dr.M.Manivel, Dept. of Geology, Bharathidasan University, Dr.S.Vasudevan, CGIT, Bharathidasan University, Dr.N.Jawahar Raj, National College, Mr. K. Dharanirajan, Pondichery University, Dr.A.Sundaram Madurai Kamaraj University and Dr.V.Selvanarayanan, Annamalai University.

Introduction A system is a simplified version of reality and is defined as a collection of interrelated parts that work together. Most systems share certain common characteristics. These common characteristics include the following: Systems have a structure that is defined by its parts and processes. Systems are generalizations of reality. Systems tend to function in the same way as nature. This involves inputs getting changed in a process and realization of new outputs. The various parts of a system have functional as well as structural relationships between each other. Owing to the functional relationships that exist between the parts there is a flow and transfer of some type of energy and/or matter. In case of information systems there is a flow of information in the structure. The parts that make up a system show certain degree of integration. In other words the parts work well together.

Introduction In a technology that consistently maintains a fantastic development curve with capabilities doubling up year-to-year, freezing the hardware specification is not easy or very meaningful. GIS (not geography) owes to its genesis and progress to the developments in information technology front. It may be asserted that any and all upgrade in the hardware industry will only add to its own ability to effectively process more and more data and handle more complex routines. The personal computers of today are seen to be adequate to run typical GIS software. A reference hardware specification is discussed here. GIS software development is an involved process but then the software developers have made good use of hardware capabilities available and have released upgrades consistently. Hardware developments are such that they defy a static spcification. However a reference specification as on 2009. An overview of various software packages used in the past as well as present is attempted. ESRI released a new version in 2002 and claimed that their ArcGIS is an “integrated collection of GIS software products for building a complete GIS that enable users to deploy GIS functionality wherever it is needed, in desktops, servers, or custom applications; over the Web; or in the field.” The details are discussed below. While a number of software overviews are available, this text is not aimed at providing a tutorial to any of the software packages nor do the comparisons made are to promote any particular software. Similarly, it is presumed that the reader is familiar with the hardware elements and functionality. Lot of information about the software packages are available on their respective web sites and the reader is exhorted to look for current, additional and in depth information required in the pages. A brief discussion on Liveware or human resource can be found at the end of the chapter.

Introduction All spatial data stored in a GIS are associated with a map projection, either implicitly (so-called “unprojected” data stored with raw longitude, latitude coordinates) or explicitly (where the data have been transformed into a known map projection). Map projections are a particularly important feature of spatial data because they introduce error and distortion, since a sphere cannot be transformed to a plane without some stretching and twisting of the sphere’s surface. The typical GIS package supports anywhere from 5 to 50 map projection types, and most projections may be modified or customized by varying their parameters. This flexibility is important for two reasons First, in order to use two or more layers together in a GIS for visualization or analysis, all data must be projected in the same way. Second, certain types of analyses, such as the measurement of area, are only valid when using certain types of projections (and conversely, are completely wrong when using an inappropriate projection).

Introduction Data are the most critical element of a GIS. It is reported that more than two thirds of the time and expenditure to develop a GIS is spent on data collection and organization. Understanding and appreciating the criticality of data is of paramount significance to practice GIS. This chapter is complementary to database concepts chapter discussed in Level II and deals with the fundamentals to start with and the concepts of building an information organization. Data - A Definition and Certain Points to Ponder “Data” are defined as a body of facts or figures, which have been gathered systematically for one or more specific purposes.”

Introduction The concept of database is the approach to information organization in computer-based data processing. (Date, 1995 and Everest, 1986). A Geographic Information System is as good as the data contained in it. Accurate and efficiently organized data are critical to the durability of the system. Data collection, capture and organization will occupy much of the time in building a GIS solution. The analysis potential of a GIS will depend on the database. It is essential to understand database concepts to practice GIS. It is erroneous to view these GIS databases as mere stores of information. The database is used to abstract very specific sorts of information about reality and organize it in a way that will prove useful during subsequent analysis. The database should be viewed as a representation or model of the world developed for a very specific application. Conversion of real world geographical variation into discrete objects is done through data models. They represent the linkage between the real world domain of geographic data and computer representation of these features. Data models discussed here are for representing the spatial information.

Introduction Data input or capture is the operation of encoding the data and incorporating in the database. The creation of a clean error free digital database is a complex and critical task determining the very usefulness of a GIS. GIS data represent not only where the graphic or cartographic features occur, but also the associated attributes of them. Data input to a geographical information system involves (a) Entering the spatial data (digitizing); (b) Entering the non-spatial, associated attributes and (c) Linking the spatial to the non-spatial data. At each stage necessary verification and checking procedures shall be deployed to ensure an error free database.

Introduction The GIS database is a model of real world. It goes without saying that there is an inherent discrepancy between GIS database and the real world it represents. This is so because all models are fraught with cognitive issues and remain as approximations. To realize the objectives of a GIS, geographical data collected, entered and processed are to be sufficiently error free and reliable. Errors can be statistical errors like mistakes, wrong inputs or faulty field surveys or system errors like excessive tolerances or high RMS error. The spatial database has further problems in the sense that the real world phenomena are not always intrinsically discrete. For instance where is the bank of a shallow river? Where is the boundary between two soil types? These are but a few questions revealing the fuzzy nature of geographic data. Many soil scientists, geographers have noticed that carefully drawn boundaries or iso-lines on maps in general give misrepresentations of change that are often gradual, vague or fuzzy. Traditional cartography as a medium of spatial data handling had a solution to such problems. But now when digital data are handled, they need to be stored with certain precision. Moreover, the spatial variation of natural phenomena is not just a local noise function or inaccuracy that can be removed by collecting more data or by increasing the precision measurement but is often a fundamental aspect of nature that occurs at all scales. (Goodchild, 1980; Mark and Aronson, 1984). This means residual unmapped variation is a remarkable problem in geographical information processing. It is therefore a prerequisite to fully understand how errors arise or propagated in GIS and what might be the effects of errors on output.

Topology building Boolean operations Query and model building Customization Introduction At human scales, the world consists of objects, events, processes, and a background environment. Cognition is about knowledge: its acquisition, storage and retrieval, manipulation, and use by humans and other intelligent creatures. Cognition includes sensation and perception, thinking, imagery, reasoning and problem-solving, memory, learning, and language. Cognitive structures and process are part of the mind, which emerges from a brain and nervous system inside of a body that exists in a social and physical world. Spatial cognition deals with the cognition of spatial properties of the world, including location, size, distance, direction, shape, pattern, movement, and inter-object relations. GIS design will be largely influenced by spatial cognition.

Introduction The term geographic information systems (GIS) has come to mean, variously, an industry, a product, a technology, and a science. As such, the term invokes different perceptions dependent on whether the viewpoint is that of the software developer, the system marketer, the data provider, the application specialist, or the academic researcher, among others. A newcomer to the field is likely to be bewildered by the multiple uses of the same term, or, seen alternatively, different definitions of the same term. For instance some find it distasteful to use of the conventional acronym GIS and prefer Geospatial Technology. With all the variety of perceptions predicting the future of GIS is a cumbersome business. The most certain inference we can gain from the available trends is, it is growing and is poised for further growth. Geotechnology along with Nanotechnology and Biotechnology is considered as of the three most promising growth industries for the near future.

Introduction Famous French postmodern philosopher Jean Baudrillard commented on information once. “Information can tell us everything. It has all the answers. But they are answers to questions we have not asked, and which doubtless don’t even arise.” This seemingly paradox observation fits contemporary Internet age perfectly. Internet is a vast repository of information of all kinds and is bursting on its seams. The seeker needs to search with monumental grit and determination to have a full handle on the range of information available for any particular search. A search string for GIS returns more than 1185000 results, in a mere 0.26 seconds. Recommending a comprehensive resource list is not possible as new material gets continually added by way of additions and updates. However for a beginner the list given below will be handy. The flip side is GIS has innumerable resources and a broad range of content. Software vendors, organizations, individuals, universities and companies have provided a wealth of information. The readers are exhorted to make use of the materials to improve their understanding of the subject.

Index A AAT 123 Adjacency 114, 118, 119, 121 Application 134, 141 ARC 11, 23, 33, 37, 47, 88, 93, 94, 97, 98, 99, 100, 102, 103, 104, 114, 115, 116, 117, 120, 121, 122, 123, 124, 131, 134 ARC snap 102, 103 ARCGIS 20, 23, 24, 25, 26, 27, 29, 30, 31, 32, 53 ARCGIS desktop 24, 25, 26, 27, 30, 31 ARCGIS desktop 26 ARCINFO 24, 25, 26, 53, 123 ARCMAP 27, 28, 31 Array 55 Attribute accuracy 92, 94, 96 Attribute display 17 Attributes 2, 3, 35, 36, 37, 54, 57, 58, 64, 66, 67, 68, 70, 71, 73, 74, 77, 83, 84, 85, 86, 92, 94