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1 Introduction to GISV ctor OlayaIntroduction to GISF oreword byGretchen PetersonIntroduction to GISText: Copyright 2018 V ctor OlayaForeword: Copyright 2018 Gretchen PetersonCover Image: The Art Journal The Industry of All Nations Illustrated Catalogue(London, England: Bradbury and Evans, 1851)Last update: June 13, 2018 This book is distributed under a Creative Commons Attribution rst met Victor when we were working at the same com-pany. During that time I learned a few interesting thingsabout him. Like how he works at such a rapid pace that ifyou blink you might nd that he s written a new plugin forQGIS or even that he s written a book like this one. Asidefrom these great qualities, the thing I most remember abouthim is that he helped direct me to the last packet of hotchocolate in the o ce kitchen, after a day full of meetingswhen I needed it the most.

2 It s helpful things like thatwhich make a di erence to people. And in this book youwill nd so many helpful things, akin to that hot chocolatebut for Geographic Information Systems (GIS), organizedin a thoughtful manner which will help you get throughthat sometimes-long GIS book is an excellent reference text regarding thehistory and basics of GIS. It includes clear examples ofconcepts illustrating choices the geospatial professionalmust make in design and layout and how those choicesa ect a map product. The reader can literally see howdecisions about line, color, shape, and other qualities willrender a map that is the most useful and the most also includes important information about the variousvways in which GIS data is obtained, how it is stored, and agreat overview of GIS book begins with the history of GIS and proceedsinto sections that discuss and de ne such topics as spatialanalysis, data visualization, web mapping and data sources,among many others.

3 I envision the book being used as ateaching tool, both in a formal setting and for , for more experienced geospatial profession-als, this book can be used in the initial ideation phase ofcreating a map, reminding us of the elements we need toconsider and prioritize to meet the objectives for a partic-ular map or analysis. It is really a digital pocket guide is generously making his book available to all,free, for users. Knowing the hours of work that go into anybook, I appreciate his attitude of community and contribu-tion to the eld of GIS. Learning and continually revisitingthe fundamentals is paramount for success in our eld. Sopour yourself a good cup of hot chocolate and get PetersonCo-author of QGIS Map DesignPrologueWhen in 2005 I started writing my book Sistemas de Infor-maci n Geogr ca , I did it for two reasons: rst, becauseno books on GIS theory had been published in Spanishsince the early 90 s; second, because there were no freebooks about GIS, except those related to free GIS software,which included little theoretical took me ve years to write the book, which ended upbeing a complete reference book with almost a thousandpages.

4 Knowing that its size and its level of detail could beintimidating, and that many people would prefer a shorterversion, in 2015, I wrote Introducci n a los SIG . Thebook you are reading now is the English translation of thatshorter what happens in Spanish, there are many goodbooks on GIS theory written in English, and new editionsare published constantly to update them with the latestchanges in the eld of GIS. However, no free book (that is,no book that can be freely copied, printed and distributed)on this topic had been published believe this book will be of great use for current GISusers and for anyone wanting to start in this fascinating eld of GIS. If you have any suggestions or comments, youcan contact me to GISWhat is GIS?Most of the information that we use nowadays is georefer-enced.

5 That is, it is information to which a geographicalposition can be assigned, and it is thus information thathas some ancillary information related to its Information System(GIS) is a toolto work with georeferenced information. In particular aGIS is a system that allows the following operations: Reading, editing storing, and, generally speaking,ma-nagingspatial data. Analyzingthose data. This includes everything fromsimple queries to complex models, which can be per-formed using thespatial componentof the data (thelocation of each value or element), thethematic com-ponentof the data (the value or element itself ), or both. Generatingdocumentssuch as maps, reports, plots, is a step beyond traditional maps. A map repre-sents a rendering of a set of spatial data, and while thisrendering has great importance within GIS, it is but one ofits many components.

6 GIS includes not only data and theirrendering, but also all the operations that can be performedon them which are part of the system, is a exible and versatile tool and most disciplinestoday use GIS in one way or another. One of the mainreasons for this is the integrative nature of GIS. The fol-lowing are some of the main contexts in which GIS playsthis integrative role. GIS as a tool to integrate information. A commonlink between most disciplines is that they study some-thing which can be located. This allows for combiningand getting results from a joint analysis. In this context,GIS provides the framework on which information fromdi erent disciplines can be added and we can work withit. GIS as a tool to integrate technologies. A large partof the technologies that have appeared in the last severalyears (and most likely those that will appear in the nearfuture) are based on using spatial information and areconnected to some extent to GIS to extend their capabil-ities and their reach.

7 Due to its central position in thisgroup of technologies, GIS plays an important role inlinking them and allowing them to communicate aroundits own functionalities. GIS as a tool to integrate technologies. GIS function-alities cover a broad range of users, most of whom wouldnot have such a well-de ned framework if it were notfor GIS itself. Consequently, there is better coordinationamong them. GIS as a tool to integrate theoretical areas. We canunderstand GIS as the sum of two disciplines: geographyand computer science. However, a more detailed anal-ysis reveals that GIS incorporates elements from manydi erent scienti c elds, such as those related to technol-ogy and data management (computer science, databasedesign, digital image analysis), those that study the Earthfrom a physical point of view (geology, oceanography,2ecology) or from a social and human one (anthropology,geography, sociology), those that study human behaviorand understanding (psychology)

8 , or those that have them-selves traditionally integrated knowledge from di erent elds, such as the already mentioned termgeomatics, derived fromgeographyandinfor-matics, frequently refers to the array of scienti c areasrelated to , we see that GIS integrates technology, in-formatics, people and geographical information, of whichthe main purpose is to capture, analyze, store, edit andvisualize georeferenced a di erent point of view, a GIS can be consideredas composed of ve main elements: Data. Data is needed for the rest of the components tomake sense and be able to serve a given purpose. Geo-graphical information, the core of GIS, lives in the data,and a detailed knowledge of the data that we use, itsquality, its origin, its characteristics, and how to manageand store it is paramount to correctly understand GISitself.

9 Analysis. Analysis is one of the main strengths of GIS,and one of the reasons why the rst GIS were devel-oped. Most GIS include analysis capabilities. They in-clude methods that were already used with traditionalcartography, others that existed but were not feasible touse without computers, and new approaches that weredeveloped speci cally after GIS appeared. Visualization. All types of information can be repre-sented graphically which makes it easier to interpret the particular case of geographical information, visu-alizing it is not only a di erent way of working with that3information, but indeed the main one, since it is the oneto which we are more maps are graphical entities, in GIS, we work withraw alphanumeric data. In order to have the same ca-pabilities of a printed map, GIS must be able to createvisual representations from that data, including map-likeones.

10 The same cartographic principles that apply whendesigning a printed map are also valid when renderinggeographic data within GIS, and GIS users must be fa-miliar with them. Technology. This includes both the GIS software andthe hardware that runs it. Additional elements that arecommon when working with GIS data, such as peripher-als used for entering data or for creating printed cartog-raphy, are included here. includes the elements that ensure aproper coordination between people, data and technol-ogy. As GIS gets more complex, managing the relationsamong its elements becomes more the following chapters, we will describe these ele-ments in of GISGIS has experienced a huge development since its earlydays. With the popularization of GIS technologies, andthanks to the help of all other disciplines that use GIS andrely on it, the eld of GIS has been rede ned and expanded,especially in the last can locate the origins of GIS in the sixties, whenthe rst GIS applications appeared.