Essentials of Geographic Information Systems Chapter 2 Map Anatomy

Chapter Map Anatomy Maps and mapping are essential components of any and all geographic information systems ( For instance , maps constitute both the input and output of a GIS . Hence a GIS utilizes many concepts and themes from cartography , the formal study of maps and mapping . Therefore , in order for us to become with , we need to learn more about cartography , maps , and mapping . The part of this chapter what a map is and describes a few key map types . Next , cartographic or mapping conventions are discussed with particular emphasis placed upon map scale , coordinate systems , and map projections . The chapter concludes with a discussion of the process of map abstraction as it relates to . This chapter provides the foundations for working with , integrating , and making maps with . URL books 31

Maps and Map Types LEARNING OBJECTIVE . The objective of this section is to define what a map is and to describe reference , thematic , and dynamic maps . Maps are among the most compelling forms of information for several reasons . Maps are artistic . Maps are scientific . Maps preserve history . Maps clarify . Maps reveal the invisible . Maps inform the future . Regardless of the reason , maps capture the imagination of people around the world . As one of the most trusted forms of information , map makers and geographic information system ( GIS ) practitioners hold a considerable amount of power and ( Wood 1992 1996 ) Therefore , understanding and appreciating maps and how maps convey information are important aspects of . The appreciation of maps begins with exploring various map types . So what exactly is a map ?

Like , there are probably just as many definitions of maps as there are people who use and make them ( see and 1998 ) For starters , we can define a map simply as a representation of the world . Such maps can be stored in our brain ( mental maps ) they can be printed on paper , or they can appear online . Notwithstanding the actual medium of the map ( our thoughts , paper , or digital display ) maps represent and describe various aspects of the world . For purposes of clarity , the three types of maps are the reference map , the thematic map , and the dynamic map . Reference Maps The primary purpose of a reference map is to deliver location information to the map user . Geographic features and map elements on a reference map tend to be treated and represented equally . In other words , no single aspect of a reference map takes precedent over any other aspect . Moreover , reference maps generally represent geographic reality accurately . Examples of some common types of reference maps include topographic maps such as those created by the United States Geological Survey ( and image maps obtained from satellites or aircraft that are available through online mapping services . URL books 32

Figure Topographic Map ' CO . I . Ex ' I . FI ?

I I . ta I runs URL books 33 Figure ) Map ( The accuracy of a given reference map is indeed critical to many users . For instance , local governments need accurate reference maps for land use , zoning , and tax purposes . National governments need accurate reference maps for political , infrastructure , and military purposes . People who depend on navigation devices like global positioning system ( units also need accurate and reference maps in order to arrive at their desired destinations . Thematic Maps Contrasting the reference map are thematic maps . As the name suggests , thematic maps are concerned with a particular theme or topic of interest . While reference maps emphasize the location of geographic features , thematic maps are more concerned with how things are distributed across space . Such things are often abstract concepts such as life expectancy around the world , per capita gross domestic product ( in Europe , or literacy rates across India . One of the strengths of mapping , and in particular of thematic mapping , is that it can make such abstract and invisible concepts visible and comparable on a map . URL books 34

Figure World Life . Figure European am a nu . an mam . URL books 35 Figure Indian Literacy Rates rate 36 40 an so 50 ED 60 10 10 an 30 59 ID 10 It is important to note that reference and thematic maps are not mutually exclusive . In other words , thematic maps often contain and combine geographical reference information , and conversely , reference URL 35

maps may contain thematic information . What is more , when used in conjunction , thematic and reference maps often complement each other . For example , public health officials in a city may be interested in providing equal access to emergency rooms to the city residents . Insights into this and related questions can be obtained through visual comparisons of a reference map that shows the locations of emergency rooms across the city to thematic maps of various segments of the population ( households below poverty , percent elderly , underrepresented groups ) Within the context of a GIS , we can overlay the reference map of emergency rooms directly on top of the population maps to see whether or not access is uniform across neighborhood types . Clearly , there are other factors to consider when looking at emergency room access ( access to transport ) but through such map overlays , underserved neighborhoods can be identified . Figure Map ( Process CUSTOMERS , URL books ) a 37

When presented in format , both reference and thematic maps are static or fixed representations of reality . Such permanence on the page suggests that geography and the things that we map are also in many ways fixed or constant . This is far from reality . The integration of with other forms of information technology like the Internet and mobile telecommunications is rapidly changing this view of maps and mapping , as well as geography at large . Dynamic Maps The diffusion of and the popularity of online mapping tools and applications speak to this shift in thinking about maps and map use . In this regard , it is worthwhile to discuss the diffusion of dynamic maps . Dynamic maps are simply changeable or interactive representations of the earth . Dynamic mapping refers more to how maps are used and delivered to the map user today ( online , via mobile phone ) than to the content of the map itself . Both reference and thematic maps can be dynamic in nature , and such maps are an integral component to any GIS . The key point about dynamic maps is that more and more people , not just GIS professionals , have access to such maps . Unlike a map that has features and elements users can not modify or change , dynamic maps encourage and sometimes require user interaction . Such interaction can include changing the scale or visible area by zooming in or zooming out , selecting which features or layers to include or to remove from a map ( roads , imagery ) or even starting and stopping a map animation . Figure ( Maps an un ' URL books 38

Figure To see the animation , go to Just as dynamic maps will continue to evolve and require more user interaction in the future , map users will demand more interactive map features and controls . As this democratization of maps and mapping continues , the geographic awareness and map appreciation of map users will also increase . Therefore , it is of critical importance to understand the nature , form , and content of maps to support the changing needs , demands , and expectations of map users in the future . KEY TAKEAWAYS The main purpose of a reference map is to show the location of geographical objects of interest . URL books 39

Thematic maps are concerned with showing how one or more geographical aspects are distributed across space . Dynamic maps refer to maps that are changeable and often require user interaction . The democratization of maps and mapping is increasing access , use , and appreciation for all types of maps , as well as driving map innovations . EXERCISES . Go to the website of the , read about the history and use of maps , and download the topographic map that corresponds to your place of residence . What features make a map dynamic or interactive ?

Are dynamic maps more informative than static maps ?

Why or why not ?

Wood , 1992 . The Power . New York . 1996 . How to Lie with Maps . Chicago University of Chicago Press . and . 1998 . Map Use . Madison , WI Publications . URL books 40 Map Scale , Coordinate Systems , and Map Projections LEARNING OBJECTIVE . The objective of this section is to describe and discuss the concepts of map scale , coordinate systems , and map projections and explain why they are central to maps , mapping , and geographic information systems ( All map users and map viewers have certain expectations about what is contained on a map . Such expectations are formed and learned from previous experience by working with maps . It is important to note that such expectations also change with increased exposure to maps . Understanding and meeting the expectations of map viewers is a challenging but necessary task because such expectations provide a starting point for the creation of any map . The central purpose of a map is to provide relevant and useful information to the map user In order for a map to be of value , it must convey information effectively and efficiently Mapping conventions facilitate the delivery of information in such a manner by recognizing and managing the expectations of map users . Generally speaking , mapping or cartographic conventions refer to the accepted rules , norms , and practices behind the making of maps . One of the most recognized mapping conventions is that north is up on most maps . Though this may not always be the case , many map users expect north to be oriented or to coincide with the top edge of a map or viewing device like a computer monitor . Several other formal and informal mapping conventions and characteristics , many of which are taken for granted , can be Among the most important cartographic considerations are map scale , coordinate systems , and map projections . Map scale is concerned with reducing geographical features of interest to manageable proportions , coordinate systems help us define the positions of features on the surface of the earth , and map projections are concerned with moving from the dimensional world to the two dimensions of a map or display , all of which are discussed in greater detail in this chapter Map Scale URL books 41

The world is a big place really big . One of the challenges behind mapping the world and its resident features , patterns , and processes is reducing it to a manageable size . What exactly is meant by manageable is open to discussion and largely depends on the purpose and needs of the map at hand . Nonetheless , all maps reduce or shrink the world and its geographic features of interest by some factor . Map scale refers to the factor of reduction of the world so it on a map . Map scale can be represented by text , a graphic , or some combination of the two . For example , it is common to see one inch represents one kilometer or something similar written on a map to give map users an idea of the scale of the map . Map scale can also be portrayed graphically with what is called a scale bar . Scale bars are usually used on reference maps and allow map users to approximate distances between locations and features on a map , as well as to get an overall idea of the scale of the map . Figure Map Scale from ( United States Survey ( 4953 IV NE SCALE 000 MILE 1000 1000 3000 401 5000 6000 7000 FEET I I KILOMETER CONTOUR INTERVAL 40 FEET NATIONAL GEODETIC VERTICAL DATUM OF 1929 THIS MAP COMPLIES WITH NATIONAL MAP ACCURACY STANDARDS FOR SALE BY GEOLOGICAL SURVEY . PO . BOX 25286 , DENVER , COLORADO 80225 A FOLDER DESCRIBING TOPOGRAPHIC MAPS AND SYMBOLS IS AVAILABLE ON REQUEST The representative fraction ( describes scale as a simple ratio . The numerator , which is always set to one ( denotes map distance and the denominator denotes ground or distance . One of the benefits of using a representative fraction to describe scale is that it is unit neutral . In other words , URL books ?

42 any unit of measure can be used to interpret the map scale . Consider a map with an of . This means that one unit on the map represents units on the ground . Such units could be inches , centimeters , or even pencil lengths it really does not matter . Map scales can also be described as either small or Such descriptions are usually made in reference to representative fractions and the amount of detail represented on a map . For instance , a map with an of , is considered a map when compared to a map with an of ( ooo , ooo ) Furthermore , while the map shows more detail and less area , the map shows more area but less detail . Clearly , determining the thresholds for or scale maps is largely a judgment call . All maps possess a scale , whether it is formally expressed or not . Though some say that online maps and are scaleless because we can zoom in and out at will , it is probably more accurate to say that and related mapping technology are . Understanding map scale and its overall impact on how the earth and its features are represented is a critical part of both map making and . Coordinate Systems Just as all maps have a map scale , all maps have locations , too . Coordinate systems are that are used to unique positions . For instance , in geometry we use ( horizontal ) and ( vertical ) coordinates to define points on a plane . The coordinate system that is most commonly used to define locations on the earth is called the geographic coordinate system ( and it is based on a sphere or . A ( ellipsoid is simply a sphere that is slightly wider than it is tall and approximates more closely the true shape of the earth . Spheres are commonly used as models of the earth for simplicity . The unit of measure in the is degrees , and locations are defined by their respective latitude and longitude within the . Latitude is measured relative to the equator at zero degrees , with maxima of either ninety degrees north at the North Pole or ninety degrees south at the South Pole . Longitude is measured relative to the prime meridian at zero degrees , with maxima of 180 degrees west or 180 degrees east . URL books 43

Note that latitude and longitude can be expressed in ( or in decimal degrees ( When using decimal degrees , latitudes above the equator and east of the prime meridian are positive , and latitudes below the equator and west of the prime meridian are negative ( see the following table for examples ) Los Angeles , US North , 15 West , Mumbai , India 58 North , 49 East , Sydney , Australia 51 South , 12 East ) Sao Paolo , Brazil 33 South , 38 West , Converting from to is a relatively straightforward exercise . For example , since there are sixty minutes in one degree , we can convert 15 minutes to ( 118 ) Note that an online search of the term coordinate conversion will return several coordinate conversion tools . When we want to map things like mountains , rivers , streets , and buildings , we need to how the lines of latitude and longitude will be oriented and positioned on the sphere . A datum serves this purpose and specifies exactly the orientation and origins of the lines of latitude and longitude relative to the center of the earth or . Depending on the need , situation , and location , there are several to choose from . For instance , local try to match closely the to the earth surface in a local area and return accurate local coordinates . A common local datum used in the United States is called ( North American Datum of 1983 ) For locations in the United States and Canada , returns relatively accurate positions , but positional accuracy deteriorates when outside of North America . The global datum ( World Geodetic System of 1984 ) uses the center of the earth as the origin of the and is used for locations across the globe . Because the datum uses the center of the earth as its origin , locational measurements tend to be more consistent regardless where they are obtained on the earth , though they may be less accurate than those returned by a local datum . Note that switching between will alter the coordinates ( latitude and longitude ) for all locations of interest . URL books 44

Map Projections Previously we noted that the earth is really big . Not only is it big , but it is a big round spherical shape called a . A globe is a very common and very good representation of the , earth . One of the problems with globes , however , is that they are not very portable ( you can not fold a globe and put in it in your pocket ) and their small scale makes them of limited practical use ( geographic detail is sacrificed ) To overcome these issues , it is necessary to transform the dimensional shape of the earth to a surface like a piece of paper , computer screen , or mobile device display in order to obtain more useful map forms and map scales . Enter the map projection . Map projections refer to the methods and procedures that are used to transform the spherical dimensional earth into planar surfaces . map projections are mathematical formulas that are used to translate latitude and longitude on the surface of the earth to and coordinates on a plane . Since there are an number of ways this translation can be performed , there are an infinite number of map projections . The mathematics behind map projections are beyond the scope of this introductory overview ( but see Robinson et al . 1995 and 1998 ) and for simplicity , the following discussion focuses on describing types of map projections , the distortions inherent to map projections , and the selection of appropriate map projections . To illustrate the concept of a map projection , imagine that we place a light bulb in the center of a translucent globe . On the globe are outlines of the continents and the lines of longitude and latitude called the graticule . When we turn the light bulb on , the outline of the continents and the graticule will be projected as shadows on the wall , ceiling , or any other nearby surface . This is what is meant by map URL books 45

Figure The Concept Within the realm of maps and mapping , there are three surfaces used for map projections ( surfaces on which we project the shadows of the graticule ) These surfaces are the plane , the cylinder , and the cone . Referring again to the previous example of a light bulb in the center of a globe , note that during the projection process , we can situate each surface in any number of ways . For example , surfaces can be tangential to the globe along the equator or poles , they can pass through or intersect the surface , and they can be oriented at any number of angles . URL books ) 46

Figure Map Projection Surfaces surfaces Flat maps In fact , naming conventions for many map projections include the surface as well as its orientation . For example , as the name suggests , planar projections use the plane , cylindrical projections use cylinders , and conic projections use the cone . For cylindrical projections , the normal or standard aspect refers URL books ) 47

to when the cylinder is tangential to the equator ( the axis of the cylinder is oriented ) When the axis of the cylinder is perfectly oriented , the aspect is called transverse , and all other are referred to as Regardless the orientation or the surface on which a projection is based , a number of distortions will be introduced that will the choice of map projection . When moving from the surface of the earth to a plane , distortions are not only introduced but also inevitable . Generally , map projections introduce distortions in distance , angles , and areas . Depending on the purpose of the map , a series of will need to be made with respect to such distortions . Map projections that accurately represent distances are referred to as equidistant projections . Note that distances are only correct in one direction , usually running , and are not correct everywhere across the map . Equidistant maps are frequently used for maps that cover large areas because they do a good job of preserving the shape of geographic features such as continents . Maps that represent angles between locations , also referred to as bearings , are called conformal . Conformal map projections are used for navigational purposes due to the importance of maintaining a bearing or heading when traveling great distances . The cost of preserving bearings is that areas tend to be quite distorted in conformal map projections . Though shapes are more or less preserved over small areas , at small scales areas become wildly distorted . The projection is an example of a conformal projection and is famous for distorting . As the name indicates , equal area or equivalent projections preserve the quality of area . Such projections are of particular use when accurate measures or comparisons of geographical are necessary ( deforestation , wetlands ) In an effort to maintain true proportions in the surface of the earth , features sometimes become compressed or stretched depending on the orientation of the projection . Moreover , such projections distort distances as well as angular relationships . As noted earlier , there are theoretically an infinite number of map projections to choose from . One of the key considerations behind the choice of map projection is to reduce the amount of distortion . The geographical object being mapped and the respective scale at which the map will be constructed are also URL books 48

important factors to think about . For instance , maps of the North and South Poles usually use planar or azimuthal projections , and conical projections are best suited for the middle latitude areas of the earth . Features that stretch , such as the country of Russia , are represented well with the standard cylindrical projection , while countries oriented ( Chile , Norway ) are better represented using a transverse projection . If a map projection is unknown , sometimes it can be by working backward and examining closely the nature and orientation of the graticule ( grid of latitude and longitude ) as well as the varying degrees of distortion . Clearly , there are made with regard to distortion on every map . There are no rules as to which distortions are more preferred over others . Therefore , the selection of map projection largely depends on the purpose of the map . Within the scope of , knowing and understanding map projections are critical . For instance , in order to perform an overlay analysis like the one described earlier , all map layers need to be in the same projection . If they are not , geographical features will not be aligned properly , and any analyses performed will be inaccurate and incorrect . Most include functions to assist in the of map projections , as well as to transform between projections in order to synchronize spatial data . Despite the capabilities of technology , an awareness of the potential and pitfalls that surround map projections is essential . KEY TAKEAWAYS Map scale refers to the factor by which the real world is reduced to fit on a map . A GIS is . Map projections are mathematical formulas used to transform the earth to two dimensions ( paper maps , computer monitors ) Map projections introduce distortions in distance , direction , and area . Determine and discuss the most appropriate representative fractions for the following verbal map scale descriptions individual , neighborhood , urban , regional , national , and global . URL books 49

. Go to the National Atlas website and read about map projections ( Define the following terms datum , developable surface , secant , azimuth , rhumb line , and zenithal . Describe the general properties of the following projections Universe Transverse ( State plane system , and Robinson projection . What are the scale , projection , and contour interval of the topographic map that you downloaded for your place of residence ?

Find the latitude and longitude of your hometown . Explain how you can convert the coordinates from to or vice versa . and . 1998 . Map Use . Madison , WI Publications . URL books so Map Abstraction LEARNING OBJECTIVE . The objective of this section is to highlight the process behind maps and to underscore the need to be explicit and consistent when mapping and using geographic information systems ( As previously discussed , maps are a representation of the earth . Central to this representation is the reduction of the earth and its features of interest to a manageable size ( map scale ) and its transformation into a useful form ( ie , map projection ) The choice of both map scale and , to a lesser extent , map projection will the content and shape of the map . In addition to the seemingly objective decisions made behind the choices of map scale and map projection are those concerning what to include and what to omit from the map . The purpose of a map will certainly guide some of these decisions , but other choices may be based on factors such as space limitations , map complexity , and desired accuracy . Furthermore , decisions about how to classify , simplify , or exaggerate features and how to symbolize objects of interest simultaneously fall under the realms of art and science ( et al . 2004 ) The process of moving from the real world to the world of maps is referred to as map abstraction . This process not only involves making choices about how to represent features but also , more important with regard to geographic information systems ( requires us to be explicit , consistent , and precise in terms of defining and describing geographical features of interest . Failure to be explicit , consistent , and precise will return incorrect inconsistent and maps , analyses , and decisions based on such maps and . This section discusses map abstraction in terms of geographical features and their respective graphical representation . What Is a Forest ?

One of the most pressing environmental issues facing the world is deforestation . Generally , deforestation refers to the reduction of forest area . This is an important issue because it has possible implications for climate change , global warming , biodiversity , and the water balance of the earth , among other things . In the last century , deforestation has increased at an alarming rate and is mostly attributed to human URL books 51

activity . Mapping forests regularly with a GIS is a logical way to monitor deforestation and has the potential to inform policies regarding forest conservation efforts . Easy enough , so lets get started . So what exactly is a forest ?

How do we know where a forest begins and where it ends ?

How can naturally caused forest fires be differentiated from those started by humans ?

Can a forest exist in a swamp or wetland ?

For that matter , what is the difference between a swamp and wetland ?

Such questions are not trivial in the context of mapping and . In fact , consistent and precise of features like forests or swamps increase the reliability and efficiency of maps , mapping , and analysis with . Figure ) in 2001 URL books 52 Figure ( rest ( in 2009 Within the realm of maps , cartography , and , the world is made up of various features or entities . Such entities include but are not restricted to hydrants , caves , roads , rivers , lakes , hills , valleys , oceans , and the occasional barn . Moreover , such features have a form , and more precisely , a geometric form . For instance , fire hydrants and geysers are considered features rivers and streams are linear features and lakes , countries , and forests are areal features . Features can also be categorized as either discrete or continuous . Discrete features are well defined and are easy to locate , measure , and count , and their edges or boundaries are readily . Examples of discrete features in a city include buildings , roads , traffic signals , and parks . Continuous features , on the other hand , are less well defined and exist across space . The most commonly cited examples of continuous features are temperature and elevation . Changes in both temperature and elevation tend to be gradual over relatively large areas . URL books 53

Geographical features also have several characteristics , traits , or attributes that may or may not be of interest . For instance , to continue the deforestation example , determining whether a forest is a rainforest or whether a forest is in a protected park may be important . More general attributes may include measurements such as tree density per acre , average canopy height in meters , or proportions like percent palm trees or invasive species per hectare in the forest . Notwithstanding the purpose of the map or GIS project at hand , it is critical that of features are clear and remain consistent . Similarly , it is important that the attributes of features are also consistently defined , measured , and reported in order to generate accurate and effective maps in an efficient manner . Defining features and attributes of interest is often an iterative process of trial and error . Being able to associate a feature with a particular geometric form and to determine the feature type are central to map abstraction , facilitate mapping , and the application of . Map Content and Generalization The shape and content of maps vary according to purpose , need , and resources , among other factors . What is common to most maps , and in particular to those within a GIS , is that they are graphical representations of reality . Put another way , various graphical symbols are used to represent geographical features or entities . Annotation or text is also commonly used on maps and facilitates map interpretation . Learning about map content and map generalization is important because they serve as the building blocks for spatial data that are used within a GIS . Building upon the previous discussion about the geometric form of geographic features , maps typically rely on three geometric objects the point , the line , and the polygon or area . A point is by and coordinates , a line is defined by two points , and a polygon is by a minimum of three points . The important thing to note is that the of a point is analogous to a location that is defined by longitude and latitude . Furthermore , since lines and are made up of points , location information ( and , or longitude and latitude , coordinates ) is intrinsic to points , lines , and . URL books 54

Figure ( us Points . Linus . Both simple and complex maps can be made using these three relatively simple geometric objects . Additionally , by changing the graphical characteristics of each object , an infinite number of mapping possibilities emerge . Such changes can be made to the respective size , shape , color , and patterns of points , lines , and . For instance , different sized points can be used to variations in population size , line color or line size ( thickness ) can be used to denote volume or the amount of interaction between locations , and different colors and shapes can be used to different values of interest . URL books 55

Figure Figure ATLAS OF FAITHS BELIEVERS as percentage oi global 453 at 13 . I . BELIEVERS BY RELIGION . Majority ! population ' 01 ' ex ( all ! 1747 I ( SUM Santa , I URL books 55 Complementing the graphical elements described previously is annotation or text . Annotation is used to identify particular geographic features , such as cities , states , bodies of water , or other points of interest . Like the graphical elements , text can be varied according to size , orientation , or color . There are also numerous text fonts and styles that are incorporated into maps . For example , bodies of water are often labeled in italics . Another map element that deserves to be mentioned and that combines both graphics and text is the map legend or map key . A map legend provides users information about the how geographic information is represented graphically . Legends usually consist of a title that describes the map , as well as the various symbols , colors , and patterns that are used on the map . Such information is often vital to the proper interpretation of a map . As more features and graphical elements are put on a given map , the need to generalize such features arises . Map generalization refers to the process of resolving associated with too much detail , too many features , or too much information to map . In particular , generalization can take several forms ( and 1991 ) The simplification or symbolization of features for emphasis The masking or displacement of detail to increase clarity or legibility The selection of detail for inclusion or omission from the map The exaggeration of features for emphasis Determining which aspects of generalization to use is largely a matter of personal preference , experience , map purpose , and trial and error . Though there are general guidelines about map generalization , there are no universal standards or requirements with regard to the generalization of maps and mapping . It is at this point that cartographic and artistic license , prejudices and biases , and creativity and design lack to shape the map . Making a map and , more generally , the process of mapping involve a range of decisions and choices . From the selection of the appropriate map scale and map projection to deciding which features to map and to omit , mapping is a complex blend of art and science . In fact , many historical maps are indeed viewed like works of art , and rightly so . Learning about the scale , shape , and content of maps serves to increase our URL books 57

understanding of maps , as well as deepen our appreciation of maps and map making . Ultimately , this increased geographical awareness and appreciation of maps promotes the sound and effective use and application of a GIS . KEY TAKEAWAYS Map abstraction refers to the process of explicitly defining and representing features on a map . The three basic geometric forms of geographical features are the point , line , and polygon ( or area ) Map generalization refers to resolving conflicts that arise on a map due to limited space , too many details , or too much information . EXERCISES . Examine an online map of where you live . Which forms of map generalization were used to create the map ?

Which three elements of generalization would you change ?

Which three elements are the most effective ?

If you were to start a GIS project on deforestation , what terms would need to be explicitly defined , and how would you define them ?

More than Just Clouds and Weather Image maps , in large part derived from satellites , are ubiquitous . Such maps can be found on the news , the Internet , in your car , and on your mobile phone . What more is that such images are in living color and of very high resolution . Not long ago , such image maps from satellites were the sole domain of meteorologists , local weather forecasters , and various government agencies . Public access to such images was pretty much limited to the evening news . Technological advances in imaging technology , in conjunction with the commercialization of space , opened the door for companies like ( and ( to provide satellite imagery and maps to the masses at the turn of the century . With online mapping services such as Google Earth providing free and access to such images , a revolution in maps and mapping was born . URL books

Image maps now provide geographic context for nightly news stories around the world , serve as a backdrop to local real estate searches and driving directions , and are also used for research purposes . The popularity and widespread use of such images speaks not only to recent technological advances and innovations but also , perhaps more important , to the geographer in us all . Figure The ( Space 2008 . Kessler , and Hugh 2008 . Thematic Cartography and . Upper Saddle River , Prentice Hall . and . 1991 . Map Generalization Harlow , England . URL books 59