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Cartographic Visualization: An Assessment andEpistemological Review*

Elaine J. HalliseyGeorgia State University

This article examines the concept of cartographic visualization. The value of cartographic visualization as anessential component in the study of geographic phenomena is discussed. Ontological and epistemologicalperspectives are addressed, with examinations of positivist, realist, postmodern, feminist, and anarchist ap-proaches to visualization. Critiques of cartographic visualization from social theorists and quantitative pos-itivists are presented. The author asserts that cartographic visualization is not restricted to any one particularepistemological framework but may combine methods of knowledge production. For comprehensive analysis ofspatial data, cartographic visualization must be included along with other qualitative and quantitative analysis.Key Words: cartographic visualization, epistemology, GIS, graphicacy.

The first concept of continental drift first cameto me as far back as 1910, when considering themap of the world, under the direct impressionproduced by the congruence of the coastlines oneither side of the Atlantic

(Wegener 1966, 1)

A1966 article inThe Cartographer, entitled

Graphicacy Should Be the Fourth Ace in

the Pack, proposed a new term,graphicacy,tocomplement the existing terms literacy, articu-lacy, and numeracy (Balchin and Coleman1966). Graphicacy, as defined by the authors,is the ability to communicate effectively andunderstand those relationships that cannot beexpressed solely with text, spoken words, ormathematical notation through the use of visualaids, particularly maps. Words or mathematicsare suitable for communication and compre-

hension in some situations, but they are inad-equate to communicate and to aid in theunderstanding of all phenomena. The authorsmaintain that graphicacy falls partially with-in the realm of mathematics and partially withinthe realm of literacy. It is interdisciplinary, but itstill maintains a separate identity. Text, mathe-matics, and graphic discourse complement oneanother, and all are necessary in various contextsfor the successful comprehension and exchangeof ideas. Literacy, articulacy, and numeracy

are aces with respect to communicationand understanding, and graphicacy, as Balchinand Coleman contend, should be the fourthace.

Over time,thenotion ofgraphicacy has evolvedinto the concept of cartographic visualization. Asimple example of the idea of graphicacy, or car-tographic visualization, is illustrated below in themap of recorded tornado origin points for the

state of Georgia (Figure 1). The data shown in thetable, representing longitude, latitude, and othervariables, were downloaded from the NationalOceanic and Atmospheric Administration(NOAA) in a text format. The numbers in thiscase reveal little with regard to the spatial distri-bution of the recorded tornadoes; context is ab-sent. A written description of the locations wouldalso be limited in terms of understanding andwould require volumes of text to describe indi-

vidual point locations in their spatial contexts. Amap of the data, on the other hand, conciselycommunicates spatial distribution, enabling theviewer to better understand patterns and rela-tionships among the recorded tornado originpoints and also among other potential map fea-tures such as populated areas, roads, and physio-graphic regions. Aspatial analytical techniquesalone are inadequate to study spatial data; map-ping spatial data is necessary to understand thedata fully.

*I would like to thank three anonymous reviewers, as well as Zhi-Yong Yin and Jeffery McMichael, for their insightful comments and suggestions. Iwould also like to thank Andrew J. Herod and the 8910 Support Group for the stimulating reading and discussion that initiated this paper.

The Professional Geographer, 57(3) 2005, pages 350364r Copyright 2005 by Association of American Geographers.Initial submission, January 2004; revised submission, August 2004; final acceptance, December 2004.

Published by Blackwell Publishing, 350 Main Street, Malden, MA 02148, and 9600 Garsington Road, Oxford OX4 2DQ, U.K.


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OSullivan and Unwin note that visualizationhas allowed some exciting recent discoveries inscience (OSullivan and Unwin 2003). For ex-ample, the mathematical equations of nonlineardynamics and chaos theory are much morereadily appreciated when displayed in graphic

form. Recognition of the power of visualizationin conjunction with advances in computer car-tography and Geographic Information Systems(GIS) has created an environment facilitatingquick and easy interactive visualization.

The purpose of this article is to examine theconcept and value of cartographic visualization.Beginning with a discussion of the evolution ofcartography from the map communicationmodel to cartographic visualization, the articlewill continue with examples of research thatdemonstrate the importance of cartographicvisualization in understanding spatial patternsand relationships for analysis, understanding,and decision making. An epistemological reviewfollows. Is the process of cartographic visuali-zation positivist, realist, postmodern, feminist,

or anarchist? Or does cartographic visualizationeven have a specific epistemological approach?Criticisms of cartographic visualization fromthe perspectives of both social theorists andquantitative positivists will then be discussed.What are some common criticisms of carto-

graphic visualization from these two knowledgecommunities? Ultimately, the two main goals ofthe article are to demonstrate the value of car-tographic visualization to geographers, andoth-ers studying spatial problems and to show that itcan be performed using different epistemolog-ical approaches.

Cartographic Visualization Defined

After Balchin and Coleman wrote their articleon graphicacy, the map communication modelbecame the dominant paradigm in cartography(Kolacny 1969; Robinson, Sale, and Morrison1978; Dent 1993). This model, proposed ini-tially by Kolacny, involves a cartographer, sep-arated from the map recipient in time and space,

Figure 1 Cartographic visualization of tornado distribution, 19501995 (Redrawn with permission from

Dent 1999, 114).

Cartographic Visualization: An Assessment and Epistemological Review 351


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conceptualizing the real world to produce amap (Figure 2). The goal of the cartographerwas to achieve as true a depiction of reality aspossible while maintaining objectivity. In addi-tion, the successful production cartographer

followed conventions of cartographic designthat were developed over time, often throughtrial and error, and supported by scientificresearch on human cognitive processes. Bymaintaining objectivity and cartographic con-ventions, the cartographers message could bedelivered effectively. Cartography textbooksfrom the mid-1950s through the 1980s empha-sized improving mapping techniques and de-sign, such as better ways to depict hachuresand determining optimal sizes for proportionalsymbols, to more effectively communicate withthe map user.

More recently, cartographers shifted empha-sis from the primacy of the map-communica-tion model to the concept of cartographicvisualization. There are a number of differentdefinitions and terms used for this concept, eachwith slightly different nuances in meaning, butthey generally refer to similar activities with thegoal of spatial data analysis and some degree

of understanding. Bailey and Gatrell (1995, 22)state that visualization means mapping. Theydistinguish visualization from exploratory spa-tial data analysis by the degree of data manip-ulation required. Visualization and exploratoryspatial data analysis occur on a continuum ofvarying levels of sophistication, they contend, sothe boundary between the two methods has be-come blurred. Haining, Wise, and Signorettaclaim that exploratory spatial data analysis

(ESDA) involves only simple and intuitivetransformations of data, enabling extraction ofinformation for hypotheses generation and theassessment of statistical models (Haining, Wise,and Signoretta 2000). Dorling and Fairbairndefine scientific visualization as the processof learning through the creation and observa-tion of abstract images, providing a methodfor seeing the unseen (Dorling and Fairbairn1997, 102). The aim of visualization, they say,is to go beyond illustration of what is known to

the discovery of what is unknown. Woodand Brodlie state that visualization is a mentalprocess (Wood and Brodlie 1994). In the con-text of what they call Visualization in ScientificComputing (ViSC), visualization is a set of tools

that enables visual data analysis. Crampton usesthe term geographic visualization (Gvis),which he defines as the maps power to ex-plore, analyze and visualize spatial datasets tounderstand patterns better (Crampton 2001,235). Kraak uses the term geovisualization torefer to the use of visual geospatial displaysto explore data and through that explorationto generate hypotheses, develop problemsolutions and construct knowledge (Kraak2003, 390).

In 1992, a group of cartographers, includingMacEachren, Buttenfield, Campbell, DiBiase,and Monmonier, defined visualization as visualanalysis of maps in either hard-copy or digitalform (MacEachren et al. 1992). Maps originallyproduced for communication purposes couldtherefore, under this definition, also be used forvisualization. By 1994, MacEachren revisedhis concept of visualization by narrowing thescope in the search for unknowns through high

levels of human-map interaction (MacEachren1994). MacEachrens hermeneutic model is wellknown in analytical cartography today (Figure3), but may not be as familiar to geographersin general. There are no boundaries in Mac-Eachrens human-map interaction space. Inthis model, three continua exist: (1) the contin-uum from private realm interaction where in-dividuals explore spatial data to public realminteraction where a wide audience may use a

published map, (2) the continuum fromspatial data exploration in which the focus isrevealing unknowns to map use in whichknowns are presented, and (3) the continuumfrom high human-map interaction to low hu-man-map interaction. Visualization is empha-sized when high human-map interactionoccurs in the private realm with the goal of re-vealing unknowns, although communicationmay also occur. Conversely, at the other end ofthe three continua, where low human-map

Figure 2 The map communica-

tion model (Redrawn with per-

mission from Robinson, Sale, and

Morrison 1978, 3).

352 Volume 57, Number 3, August 2005


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interaction occurs in the public realm andknown spatial information is presented, com-

munication is emphasized, but some visualiza-tion may take place.

According to MacEachren, visualizationworks through an iterative process of com-paring observations with knowledge, a seeingthat-reasoning why cycle, unlike the linear na-ture of language that forces a sequential pres-entation. In the process of visualization, thereis a continual give-and-take between visionand visual cognition through the intermediary

of knowledge schema (MacEachren 1995,36667).Although the terms for cartographic visual-

ization may differ, the definitive goal is theunderstanding of spatial information andknowledge through interactive visual display.MacEachrens model encompasses the tradi-tional map and its use as a tool for communi-cation in the public realm, but it also emphasizesthe value of cartographic visualization in trulyunderstanding geographic phenomena. Alongwith cartographers, geographers in generalmust be aware of the importance of cartograph-ic visualization to more completely understandspatial data. In the remainder of the article, theterm cartographic visualization, as defined byMacEachren, will be used.

Cartographic Visualization

Capabilities in a GIS Environment

Typically performed in a GIS environment, car-tographic visualization may involve explorationof one or more layers of geographic data. Usingcartographic visualization techniques, the usercan determine the following types of informa-tion: (1) where a specific feature or attribute(i.e., a characteristic of a feature) is located, (2)what is at a specific location, (3) how featuresand attributes in one or more layers are spatially

related, or (4) if there are anomalies in the data.If data from various time frames are available,they may be visualized to establish the kinds ofchange that have occurred over time. As willbe shown, Scientific visualization allows usersto interpret, validate, and explore their datain greater detail than was possible hitherto(Longley et al. 2001, 264).

Researchers have developed numerous rec-ommendations and software tools to enhancecartographic visualization. Kraak categorizesthem as query, reexpression, multiple views,linked views, animation, and dimensionality(Kraak 1999). Query is a simple function inwhich the user clicks on an object to obtain in-formation about its attributes. Reexpression ischanging the display of data in some wayfor

Figure 3 MacEachrens model

of cartography (Redrawn with per-

mission from MacEachren 1994).



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instance, using a range of thematic mappingtechniques, such as choropleth, dot density, orproportional symbol mapping or using a varietyof classing techniques for quantitative at-tributes. Employing small multiples, or multi-

ple views, means using sets of maps for differenttime periods, variables, or classes to enable aholistic view of the data. Linking views, alsocalled brushing, is a cartographic visualizationtechnique that links maps with other graphics,such as bar charts and scatter plots (Monmonier1990). When an object is selected in one of thegraphics, the corresponding element will be se-lected on the other graphics. Animation aids ineffective visualization of dynamic, temporaldata, and dimensionality. Dimensionality is por-traying data in other than a two-dimensionalview from above and may be combined withanimation to create three-dimensional flyovers.

Three recent examples of work, out of manyin which cartographic visualization is a keycomponent of the analysis, include a study ofweather visualization in aviation, a project con-cerning the alpine treeline ecotone in GlacierNational Park, and an illustration of distributedmapping. The authors of the aviation study,

who aim to provide weather graphics to helppilots more easily and quickly visualize the bigpicture, focused on interactive graphic displaysof meteorological observations, terminal areaforecasts, and winds aloft forecasts to aid pilotsin weather briefing and route selection (Spir-ovska and Lodha 2002, 170). The pilots whoevaluated the cartographic visualization toolsfound them to be very useful when compared toother methods of weather data gathering, such

as the limited cartographic visualization recent-ly available to pilots through the Web or weath-er briefings via telephone or aircraft radio.Weather maps, in general, are a type of carto-graphic visualization familiar to much of thepopulation of the U.S. In this example, the pi-lots preferred the interactive cartographic vis-ualization to generate knowledge of the weatherpatterns for informed decision making.

In the second example of cartographic visu-alization, researchers used mapping, modeling,and visualization to examine processes that in-fluence the spatial organization of the alpinetreeline ecotone in Glacier National Park(Walsh et al. 2003). An ecotone is a region ofrapid transition between two adjacent ecosys-tems. The authors state that visualization aided

understanding of fine-scale geomorphic pat-terns and their relationship and influence on thealpine treeline ecotone. In their research, theauthors used interactive multimedia GIS dat-abases that included animations, flyovers, three-

dimensional representations, text, and othermeans to explore the data. The various carto-graphic visualization approaches were used aspart of the final analysis and to generate addi-tional hypotheses.

The third example of cartographic visualiza-tion is an online, interactive, three-dimensionalpresentation of the campus of George MasonUniversity, an exemplar for many distributedmapping applications (Crampton 2001). Thevisualization allows the useranyone witha suitable Internet connectionto navigatethrough the campus from multiple perspectivesand multiple scales, fostering a more completeunderstanding of the campus than would a tra-ditional two-dimensional static map.

The importance of using cartographic visu-alization for analysis, understanding, and deci-sion making, is demonstrated in these threeexamples, with the last showing how visualiza-tion is becoming more democratized and user

friendly. It is more difficult to evaluate hownotusing cartographic visualization might nega-tively affect the analysis of spatial data. One areaof study in which there is potential for furtherinvestigation of the benefits of cartographic vis-ualization is that of the relationship betweenpopulation distribution and recorded torna-does. A number of physical geographers, clima-tologists, meteorologists, and others have notedthere is likely to be an urban to rural bias in

recorded tornadoes (Balling and Cerveny 2003;Hage 2003; Ray et al. 2003). Historically, tor-nadoes were recorded through direct observa-tion, so it stands to reason that in areas of lowpopulation density, tornado sightings would belower than in urban areas where humans andsevere storms intersect. Indirect evidence forthis bias is cited in several studies indicating thattornado frequencies have increased by a factorof ten over the last fifty years, probably dueto increasing populations available to sighttornadoes (Balling and Cerveny 2003). Otherresearchers, using different quantitative tech-niques, have concluded the opposite; that therehas been no apparent relationship between ruralpopulation density and tornado occurrence(King 1997; COMET Outreach Program



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2000). Adding cartographic visualization tech-niques, such as density surface mapping,1 to theavailable analytical tools could help clarify theproblem by presenting the data in alternativeways. Stated succinctly, computational and

visual techniques are complementary, and theircombined use may produce a synergistic effect(Andrienko, Andrienko, and Gitis 2003, 380).

Ontological and Epistemological

Considerations

For the most part, practitioners of cartographyhold the materialist view that phenomena existin the world independently of the mind, andempiricism is a suitable approach, as opposed tothe idealist, or Neo-Kantian view, which con-tends that nothing exists outside the mind tocreate perceptions. In the neo-Kantian view,space is conceptualized as a condition of howpeople understand the world. Raper (1999)states that most spatial representations are aproduct of materialist, or what he calls scientif-ic, ontology. Spatial representations, he asserts,are made within the scientific worldview be-

cause those holding other views do not considerspatial representations to be particularly im-portant for understanding the world. For thoseholding the materialist view, the goal of spatialrepresentation is to obtain or depict some es-sence of the existing and observable real world.Furthermore, spatial representations are a typeof observation themselves.

Raper (1999) further distinguishes concep-tions of space and time in spatial representation.

He notes that some regard space and time in afixed, universal, or Newtonian framework, usu-ally equipped with a Cartesian coordinate sys-tem. This conceptualization means ontology,theory regarding the nature of being, is imposedonto perceptions of phenomena. In recent dec-ades, alternative notions of space-time in gen-eral relativity and quantum mechanics havesparked an interest in the idea of relative space.Raper has incorporated a relative, Leibnizianontology into his research to account fordynamic environments, such as coastlines. Inthis case, the ontology is generated from thebehavior of the phenomena.

In recent years, most physical geographershave remained firmly established within theempirical, rational worldview and see little

cause for debate regarding traditional carto-graphic representations of space. Human geog-raphers, on the other hand, have adoptedvarious conceptions of science. Based uponthese differing ontologies, some observers of

the discipline have divided geographers intotwo factions. The spatial analysts include thephysical geographers and some human geogra-phers, whereas the remaining human geog-raphers tend to be critical social theorists( Johnston 1999). In reality, geographers whoare spatial analysts as well as critical social the-orists do exist. Geographers who fall into nei-ther camp also exist. Nevertheless, significanttension has been evident between the twoknowledge communities for some time, withcritical social theorists seeking to problematizemapping and visualization (Perkins 2003). Alack of cross-citation in the cartographic liter-ature demonstrates the schism. This divide willbe examined further in an upcoming section oncritiques of cartographic visualization. In thefollowing sections, the epistemology of carto-graphic visualization, the philosophical theoryof how cartographic knowledge is produced,gained, sent, and changed, will be explored.

Positivist Visualization

Extensive debate on the epistemological ap-proach in cartography has been evident in therecent literature. For some time, cartographyhas been viewed as positivist. Positivism, em-pirical and rational, works toward the discoveryof cause and effect in an instrumentalist manner.Explanation lies in the observation of well-identified regularities. Positive reality, in its tra-

ditional sense, is static, as an enduring relation-ship exists between cause and effect, allowingthe creation of general laws and theories to aidin prediction. Positivism assumes the infallibil-ity of science and emphasizes a properly exe-cuted scientific method, preferably deductiverather than inductive. It stresses detachmentand objectivity on the part of the researcher aswell. Numbers are sacrosanct in conventionalpositivist philosophy.

Traditional cartography, under the commu-nication model paradigm of the middle to latetwentieth century, certainly exhibits a positivistaim in mapping, particularly in its stated goal ofobjectivity and the search for a perfect pres-entation of reality through continual improve-ment in technique and design. Some critical



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social theorists consider Newtonian and Carte-sian spatial representations to have positivistunderpinnings, and cartographys associationwith quantitative spatial analysis renders it pos-itivist in their eyes. Under the newer paradigm,

which includes a private-realm, cartographicvisualization component, the epistemologicalapproach is less clear. Some cartographers stillcreate maps for public presentation, but morerecent cartographic textbooks recognize thesubjectivity involved in cartographic designfor presentation (Dorling and Fairbairn 1997;Slocum 1999). With regard to cartographicvisualization, some researchers use positivistterminology in their writings. For example, Ha-ining, Wise, and Signoretta justify the use of vis-ualization by stating that graphical methods arefelt to be more intuitive for nonspecialists to usethan methods of numerical spatial statistics. Ac-cording to these scientists, exploratory spatialdata analysis tools are a step toward enablingresearchers to formulate hypotheses and toassess statistical models (Haining, Wise, andSignoretta 2000, 122). They state that ESDAis inductive, and the aims are descriptive. ForOSullivan and Unwin, visualization must usually

be supplemented with spatial statistical tech-niques to determine if the apparently obvious issignificant (OSullivan and Unwin 2003, 20).

Realist Visualization

Other theorists contend that GIS and, there-fore, cartographic visualization in a GIS envi-ronment, is epistemologically realist (Mark1999; Schuurman 2002; Perkins 2003). Ration-al and empirical, as is positivism, realism asserts

that cause and effect are contingent on context.In other words, in one situation, A may lead toB, but in another situation, A may leadto C. Realist researchers seek causal relation-ships and mechanisms and employ bothqualitative and quantitative methods. Realismstresses the possibility and relevance of non-observable theoretical entities, or essences,and recognizes that science is fallible and sub-jective. In human geography, it encourages in-teractivity between the subject and object ofstudy. Realism is a more critical epistemologythan positivism.

Cartographic visualization in the realist moderecognizes the subjectivity inherent in research,including the forms of spatial representationselected. Schuurman maintains there is an

implicit belief among those who practicecartographic visualization that spatial repre-sentations represent a real link with physicalspace and geographical processes. These spatialrepresentations are a form of abstraction that

may be used to identify causal mechanisms andstructures that lead to phenomena under certainspecific conditionsa realist goal. The recentincorporation of relative space-time dimen-sions, such as those of Raper, enables theachievement of a more nuanced, contingentrepresentation. Although GIS, and its subrealmof cartographic visualization, is often concernedwith prediction, these newer forms of represen-tation may encourage the achievement of therealist aim of explanation.

A cohort of researchers has defined experien-tial realisma new brand of realism basedon thework of George Lakoff, a professor of linguisticswith an interest in cognitive semantics. Cogni-tive semantics is a field that attempts to under-stand the mind through empirical studies of theway people categorize. Lakoffs studies suggestan inherent spatiality in human thinking andlanguage that accounts for human cognition aswell as structures and mechanisms (Lakoff 1987).

Human cognition (i.e., perception, reasoning,and memory) and the world of measurement arecompatible in many ways. Cognitive spatial re-lations are primarily topological, objects are ad-jacent to one another, objects connect to oneanother, and objects may be within or outsideoneanother, forinstance,butmetric factors, suchas distance measurements, refine those cognitivespatial relations. According to Mark (1999, 81),experiences providefeedbacksthattune internal

mental maps to match reality. Based on Lakoffsresearch, Mark also states that, unlike other typesof cognitive functions, spatial relationshipsseem to be very similar in disparate culturesand languages (Mark 1999, 87).

Postmodern Visualization

A realist epistemology for cartographic visuali-zation is currently accepted by some, but otherswould add that the methods are postmodern(Slocum 1999). Postmodernists believe that tomore fully understand the issues, problemsshould be approached from multiple perspec-tives and should be democratic in nature.All-encompassing theories or explanations, ormetanarratives, are viewed with suspicion. De-construction, a notable postmodern technique,



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enables the researcher to uncover hidden mean-ings and agendas. In cartographic visualization,there is no single correct way to represent data.Multiple views and perspectives are recognizedas vital to seeing and understanding spatial data

relationships. Crampton advocates distributed,or democratic, mapping, as described previous-ly, with the distinction between the cartographerand the user becoming blurred as more peopleare creating their own maps (Crampton 2001).Kraaks description of visualization includesmention of the importance of viewing geospa-tial data in alternative ways, such as multiplerepresentations without constraints set up bytraditional techniques or rules (Kraak 2003,391). OSullivan and Unwin (2003, 19) say vis-ualization often turns traditional researchprocedures upside-down by developing ideasgraphically and then presenting them by non-graphic means. Both statements demonstratedecidedly postmodern ideas.

Feminist Visualization, Anarchist

Visualization, and Section Summary

Kwan argues for a feminist visualizationthrough recorporealizing all visualizations asembodied and situated practices (Kwan 2002,649). She counters arguments contending GISand visualization are purely positivist activitieswith the following statement:

that GIS technology or methods assume partic-ular epistemologies represents a form of tech-nological determinismthe use of a particulartechnology necessitates a particular mode ofknowledge productionwhere the possibility

for GIS users/researchers to assume other per-spectives is entirely ruled out. This view erasesthe very subjectivities and agency of individualGIS practitioners, who may be willing to adopt acritical sensibility and to renegotiate GIS asa critical practice.

(Kwan 2002, 648)

According to Kwan, feminist geographers canharness the power of the visual technologiesof GIS to re-present the world with the goal ofdestabilizing dominant representations that si-lence, and are insensitive to, the effects of op-pression and violence. The purpose for usingfeminist visualization in a GIS environment isnot to make universal laws but to understandgendered experiences and to represent gende-red spaces across a range of differences. She as-

serts that the focus for practicing reflexivity, orsituatedness, a vital part of feminist epistemol-ogy, can and should be undertaken at three sites.These are: (a) the site of production, where themeaning making of visual practice occurs; (b)

the site of the visual image, where the powerof representations is evident; and (c) the site ofaudiencing, where meaning is interpreted byothers. GIS users can interact with GIS-basedvisualizations in a meaningful, reflexive way.Kwan gives several examples of feminist visual-izations, including studies of womens life pathsin space-time and cartographic narratives inethnographies.

Cartographic visualization has thus far beendescribed as positivist, realist, postmodernist,and feminist. Interestingly, it has also beencalled an anarchistic pursuit (Sibley 1998). Inthe antiauthoritarian, anarchist view of theworld, there is a desire to live dangerously andto bend or break the conventional knowledgeboundaries. Anarchism is similar to postmod-ernism in that both try to decenter knowledgeand make it more democratic. Exploratory spa-tial data analysis, as opposed to confirmatorystatistical methods that attempt to impose spa-

tial order, provides no prescribed procedures.There are no points at which decisions must bemade, leading to an intimate relationship be-tween the researcher and the data, according toSibley. He states that Because there is no nec-essary hierarchy of methods, because there areno answers, no solutions, no rejection of the re-sidual, exploratory methods are compatiblewith an anarchistic science, that is, a sciencewith few rules and many ways of proceeding

(Sibley 1998, 243).Each of these epistemological perspectives oncartographic visualization has some validity. Car-tographic visualization may involve the positivistquest for continual improvement of techniqueand design, a realist recognition of subjectivity,the postmodern practice of viewing from manyperspectives, feminist reflexivity, and anarchistexploratory methods with few rules; all are waysto produce, gain, send, and change knowledge.An individuals worldview, or ontology, helps todetermine that individuals epistemological ap-proach to cartographicvisualization. To reiterateKwans statement quoted above, technologicaldeterminism must be avoided (Kwan 2002). Car-tographic visualization need not always be basedupon one particular philosophy of knowledge.



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Individuals using cartographic visualization mayadopt one or even a combination of epistemo-logical approaches.

Critiques of Cartographic

Visualization

Critics of cartographic visualization come froma number of different epistemological schools ofthought, including critical social theorists, fem-inists, and quantitative positivists. Critiquesfrom the social theorist and feminist side dem-onstrate some degree of overlap, given that theyare both critical approaches. The quantitativepositivists, on the other hand, are at the opposite

end of the spectrum regarding the facets of car-tographic visualization they choose to criticize.These perspectives will be examined, beginningwith those of the critical social theorists andfeminists.

Critiques from Critical Social Theorists

and Feminists

As Perkins notes, profound differences exist be-tween those who research mapping from a prac-tical perspective and those who critique the map

and the mapping process (Perkins 2003). Car-tographers focus on new methods of visualiz-ation and representation, whereas criticaltheorists look at mapping as a social constructand exercise of power. Because of these dissim-ilar perspectives, the two camps pose differenttypes of questions and, as noted previously,maintain separate knowledge communities withlittle cross-citation and some academic hostility.In the broad picture, this is part of what Schuur-

man calls the science wars, which is not justskepticism toward GIS and its visualization ca-pabilities, but skepticism toward all science(Schuurman 2002, 77). Several researchers, in-cluding Kwan, Schuurman, and Sui, have at-tempted to bridge the gap between the usersof cartographic visualization and the criticaltheorists.2

Much of the criticism, even recent criticalcontemplation, draws from concepts associatedwith the old map communication model and itspositivist, authoritarian approach. Harley, whosaid cartography is seldom what cartographerssay it is, used the postmodern technique of de-construction to read between the lines of thegraphic text of mapping to reveal a rhetoricaldimension (Harley 1989, 1, 7). Harley notes the

rules of ethnocentricity, where the world mapcenters on the society in which the map isproduced, thereby legitimating that societysworldview. He also describes spatial hierarchi-calization, in which the cartographer creates a

visual hierarchy based upon the societal powerstructure using symbolization (e.g., larger textrepresenting features perceived to be more im-portant). Harley contends that although the au-thority of maps is rarely questioned, mapsare subjective and culturally produced. Theyare political and work as a form of power-knowledge where ethics and justice are oftencompromised. Crampton asserts that Harley isaiming to reinterpret mapping as a nonpositivistendeavor because even though it claims objec-tivity, it is a subjective practice (Crampton2001).

In addition to Harley, others offer concreteexamples of social construction in public-realmcartography (Brealey 1995; Monmonier 1996).For example, Brealey discusses the Europeanmapping of First Nations lands where edgesinevitably beget space. According to Brealey,Europeans defined territory and confirmedownership through these cartographic con-

structions of reality (Brealey 1995, 149). Mon-monier addresses social construction withregard to the selection of map projections, sym-bolization, scale, and other activities associatedwith presentation cartography. He recognizesthat to avoid hiding critical information in afog of detail, the map must offer a selective, in-complete view of reality (Monmonier 1996, 1).

The deconstructionists present legitimate ar-guments with regard to static maps produced

within the map communication framework. Asnoted earlier, cartographers are still producingmaps for public presentation. Subjectivity maybe unintentional for these cartographers, butmaps are often created under the direction ofagencies with definite biases.3The more recentparadigm of MacEachren recognizes subjectiv-ity and emphasizes the exploratory analysis ofcartographic visualization, and so some of thedeconstructionist arguments are therefore ad-dressed. For instance, Crampton contends thatan implication in Harleys work stresses theimportance of multiple perspectives and multi-ple maps and, as stated previously, cartographicvisualization emphasizes multiple perspectives.There is no single, perfect view. That is not thegoal.



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With regard to the issues of power-knowl-edge, Rd, Ormeling, and Van Elzakker (2001)state that professional cartographers have beenresistant to the democratization of visualization.Many cartographers lament the advent of map-

ping software that enables untrained users tocreate products that violate the rules of carto-graphic convention. Cartographers may havelegitimate cause for concern here with regard toissues such as choice of map projection. For in-stance, in dot density mapping, it is important touse an equal area projection because the dot perarea relationship is the quantity being mapped.If enumeration unit area relationships are notmaintained, then relative densities are depictedincorrectly. Fortunately, some software compa-nies have anticipated these problems, offeringthe option of automatic, equal area projectionwithin the cartographic visualization environ-ment.4 The projection changes as the userchanges the map center or scale. It is hoped thatas the technology advances, other cartographicvisualization concerns may also be addressed.

Cartographers also fear the profession of car-tography will become obsolete. Nevertheless,Rd and his coauthors advocate a democratiza-

tion in cartographic visualization. Instead ofviewing mapping software as threatening to theprofession, cartographers should realize that itmight lead to an increased general understand-ing of how maps and map displays function asboth devices for communicating knowledgeabout geographic phenomena and as tools forexploring these phenomena.

People are often less skeptical of maps thanwritten or oral forms of communication, hence

the calls for deconstruction. As these carto-graphic tools become more available, theirsocial-manipulating power is likely to declinebecause of increasing awareness of their limi-tations and the likelihood of subjectivity inpresentation maps. According to Dorlingand Fairbairn, democratization demystifies themaking of maps and enables critical voices(Dorling and Fairbairn 1997). Crampton, asnoted previously, also advocates what he callsdistributed mapping, potentially via the Inter-net, to change power relations. Democratiza-tion blurs the distinction between cartographerand map user; the map user becomes thecartographer.

Returning to the argument about the author-itarian nature of maps, a technical group notes

that many maps, and their associated digitaldatabases, are depicted as if they represent ab-solute certainty (Elith, Burgman, and Regan2002). They, and others, call for the mapping ofepistemic and linguistic uncertainty. Epistemic

uncertainty is uncertainty about a determinatefact such as measurement error, sampling erroror bias, natural variation, or model uncertainty.Linguistic uncertainty results from natural lan-guage and includes vagueness, ambiguity, andunderspecificity. For example, polygons repre-senting soils classes are an arbitrary classifica-tion of a vague concept and are clearly acontrived representation of reality. It is under-stood by ecologists that soils do not fall intodistinct classes, but this is not always explicit incartographic visualization. Both epistemic andlinguistic uncertainty are present in spatial dataand should be indicated. The authors suggeststoring visualizations of uncertainty in a GISto inform decision makers of regions that areprone to error or that seem to be well modeled.It is worth noting that at least one existing soft-ware package does offer functionality for deal-ing with these types of uncertainty.5

Most cartographic visualization in a standard

GIS environment still takes place in simpleCartesian space, which leads to limitations. Inworking with network information, Rugglesand Armstrong rely on a representation of spacethat is non-Cartesian (Ruggles and Armstrong1997). True scales are not always maintained intheir visual analysis and representation. Muchof their work is similar to linear cartograms suchas the well-known map of the London Under-ground (Transport for London 2004). Ruggles

and Armstrong call for a variety of representa-tions of space in visualization software. Dorlinghas done extensive work on the subject ofarea cartograms for cartographic visualization(Dorling 1994). Recognizing the utility ofcartographic visualization in non-Cartesianspace, he has developed computer algorithmsto easily generate value-by-area cartograms.

In feminist literature, the notion of vision as apath to knowledge has been scrutinized (Kwan2002). A number of feminist theorists havewritten of the gods-eye view, the masculinist,objectifying power of an elevated, disembodiedvision, elevated and disembodied both meta-phorically and materially (e.g., through carto-graphic visualization or remote sensing). Anobjective, disembodied view leads to distance



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the knowing subject from everybody and eve-rything in the interests of unfettered power . . .but of course that view of infinite vision is anillusion, a god-trick (Haraway 1991, 18889).Sparke writes of the masculinist ocularcen-

trism of Halford Mackinder, a geographer ofthe late nineteenth century with imperialistleanings, who had a fascination for cartography(Sparke 2000).

Haraway does believe there aresuitable ways oflooking from a situated view where social effectsare considered. She says, Only the god-trick isforbidden (Haraway 1991, 189). Kwans ideasregarding appropriate ways of feminist visualiza-tion were examined in the previous section onfeminist visualization. In Kwans words: Giventhat objectification can also occur through othermeans, such as the use of language, the problem isless the use of vision or GIS-based visualizationsper se than the failure to recognize that vision isalways partial and embodied and to acknowledgethe risk of privileging sight above the other sens-es (Kwan 2002, 649).

Kwan recognizes the malleability of GIS andoffers specific strategies to overcome such limi-tations as the lack of readily available procedures

in current software for representing genderedbodies and womens desires, as well as managingprocesses involved in the social construction ofspace and unequal power relations. She recom-mends complementing secondary data sourceswith other contextual information, collectingqualitative or quantitative primary data fromindividuals, developing dedicated algorithms in-stead of out-of-the-box solutions, and practicingreflexivity regarding knowledge production and

representational tactics.

Critiques from Quantitative Positivists

Positivist critiques of cartographic visualizationare not as extensive as those expounded by crit-ical social theorists. Whereas many criticalsocial theorists still view cartographic visuali-zation as positivist with a quantitative bent,quantitative positivists view cartographic visu-alization as descriptive rather than confirmatory(Haining, Wise, and Signoretta 2000). Carto-graphic visualization also uses inductive rea-soning, which is considered by many to be lessrobust than deductive reasoning.

Response to these criticisms warrants somediscussion of deductive methods. With regardto the search for cause and effect through the

scientific method, positivists, as previously not-ed, favor the deductive process. Using the tra-ditional deductive process to prove a hypothesisthrough experimental data is now viewed bysome researchers as illogical, for even with ex-

perimental replication, there is always the pos-sibility of an exception. Falsification, the newerframework, does not lead to absolute truthonly the probability of truth, under specificconditions, through significance testing. In cur-rent, appropriately used scientific method, ex-periments cannot prove hypotheses; they aredesigned to falsify null hypotheses in a never-ending, cyclical manner. The research hypoth-esis may be accepted, but it is not proven. Thesearch for cumulative negative evidence is theimportant component. Definitive answers areunattainable; there is always some small prob-ability of rejecting a null hypothesis when it istrue or not rejecting a null hypothesis when itis false. Through falsification, the deductivemodel has, in essence, become inductive.

Subjectivity is also a concern. Unlike realist,feminist, and other epistemologies where sub-jectivity is expected and sometimes explicitlyencouraged, subjectivity is actively eschewed in

positivist analysis. Objectivity in research is astated aim, with the assumption that subjectivitydenotes bad science. Positivists maintain that apriori assumptions about data lead to bias incartographic visualization. In other words, theresearcher will see what (s)he wants to see. Ofcourse, the goal of true objectivity may be im-possible to attain, with many researchers assert-ing that all scientific endeavors aim to prove apriori assumptions. Although standardized sta-

tistical results may be replicated and compared,as one geographer states, Personal opinion andprior experience will always have some influ-ence on conclusions derived from statistics(Brodsky 2002).

There is also some question regarding cog-nitive issues. Cognitive research on map com-munication from the 1960s and 1970s tested theability of map users to determine statistical cor-relations among mapped variables (Lloyd andSteinke 1977). The researchers had already per-formed quantitative analysis and were attempt-ing to communicate the results to the mapaudience; a very different goal from todaysprivate-realm, highly interactive visual analysis,where cartographic visualization comes first andmay lead to further quantitative analysis. Lloyd



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and Steinke found that a direct relationship ex-ists between hard-copy map complexity and er-ror in visual comparison, but they did not havethe tools at that time to consider cartographicvisualization in an interactive GIS environment.

Today, some researchers state there may becognitive shortcomings in cartographic visual-ization. There is a tendency to emphasize theimportance of illusions as a danger in carto-graphic visualization. In response, Petch notesthat illusions are of little importance: Theyoperate like badly written sentences which may,at first sight, cause confusion but which are eas-ily decoded in context (Petch 1994, 218).

Traditional quantitative positivists considercartographic visualization to be either an op-tional, possibly useful, step toward the final goalof confirmatory spatial statistics or beneficialfor the display of output from analysis (Bailey1994). This perspective, primarily from thephysical side of geography, is that cartographicvisualization is not powerful enough, especiallywhen working with multivariate data, for effec-tive analysis. Spatial statistics are required toverify and validate the data.

Concluding Thoughts

The two primary aims of this article were todemonstrate the value of cartographic visuali-zation as an essential part of a comprehensiveanalysis of geographic phenomena and to showthat it can be undertaken using different epis-temological approaches. A brief history of car-tographic visualization addressed the conceptsof the map communication model and graph-

icacy, which is the ability to effectively commu-nicate and understand relationships throughvisual aids that cannot be expressed solely withtext, spoken words, or mathematical notation.MacEachrens characterization of cartographicvisualization is the result of the evolution ofthese earlier concepts and includes both publicrealm map communication as well as privaterealm interactive visual analysis. Several specificexamples of the visual analysis of spatial data,among innumerable others, demonstrated thevalue of cartographic visualization in the studyof geographic phenomena, particularly for in-teractive analysis. As acknowledged, it is moredifficult to determine the negative effects of notusing cartographic visualization in the analysisof spatial data, but when results in scientific re-

search on spatial data conflict, cartographic vis-ualization may help to clarify understanding.

With regard to defining the epistemologicalapproach of cartographic visualization, techno-logical determinism must be avoided. The proc-

ess of cartographic visualization takes on theepistemological approach of the researcher, so itmay incorporate positivist perspectives, realistperspectives, or other modes of knowledge ac-quisition and production.

Criticisms of cartographic visualization comefrom various epistemological standpoints. So-cial theorists tend to focus on public-realm mapcommunication, claiming it to be subjective,ethnocentric, and culturally produced, therebyhelping to maintain the status quo with respectto power relationships. Social theorists havecalled for greater democratization, which, infact, is occurring in cartography and GIS today.Quantitative positivists agree that cartographicvisualization is subjective, but many also argue itis descriptive and inductive and, therefore, in-adequate for robust analysis. Is objectivity trulyattainable? Educated in a decidedly positivistenvironment with current leanings toward amore realist perspective, I would say there is

some subjectivity inherent in all research; inchoosing which data to analyze, which methodsof analysis to perform, and in how results areinterpreted. It is true that cartographic visual-ization is inductive, but falsification in themodern scientific method also involves someinductive reasoning, as discussed.

Some cartographic visualization may be de-scriptive or qualitative, but it is useful for seeingpatterns and relationships and sometimes drives

the direction of research, especially when visu-alizing data in the private realm. As noted earlierin the article, the high levels of human-map interaction in private-realm cartographicvisualization engender a more completeunderstanding of the spatial data. The individ-ual researcher has access to the data source, notjust final production maps, and may generatemultiple views, using different algorithms, ofthe same data. For example, in interpolating asurface of mean minimum temperature fromsample points for a study area, the researcherhas the option of using inverse distance weight-ing, spline, or kriging, among other geostatis-tical methods. Some methods are better thanothers, depending upon the type of data, thedistribution of the sample points, and other



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factors. Additionally, techniques for estimatingerror exist. The researcher also has the option ofcreating a contour map or a gridded surface tovisualize the data. The patterns revealed amongvarious layers of data in the cartographic visu-

alizations could suggest a direction for theresearch process. An astute researcher uses car-tographic visualization techniques throughoutthe analysis of spatial data and is intimatelyinvolved in the mapping process, either byconducting his or her own cartographic visual-ization or by working closely with those who areperforming the cartographic visualization. Em-ploying a mapping technician who is unfamiliarwith the topic under study to decide the mostsuitable way to map the data would certainly bedetrimental to the research. Employing a car-tographer to map results after the analysis is alsounfavorable in that the opportunity is missed tointeractively and comprehensively investigatethe spatial data.

In conclusion, no matter the epistemologicalor ontological considerations, it is best to comeat any problem from many different perspec-tives. A single method or approach may not bethebestinallcasesandcouldbelimitedinmost.

The incorporation of qualitative and quantita-tive information, text, and numbers, as well asthoughtful cartographic visualization, leads to amore complete understanding of geographicdata. In conjunction with text, spoken words,and mathematics, cartographic visualizationcompletes the metaphor of Balchin and Cole-man. Modifying their words, in spatial research,graphicacy must be the fourth ace in thepack.

Notes

1 It can be difficult to analyze point patterns visuallyfor a number of reasons, including point coalescenceand overlap. Points are often obscured and actualnumbers hard to estimate. One way to improve car-tographic visualization of point data is to create adensity surface. Described simply, a density surfacecalculation results in a gridded map layer in which

each grid cell value represents a density calculation(e.g., number of tornadoes per square unit of meas-ure) for a user-specified radius surrounding each cellcenter. Calculating a density surface is differentfrom geostatistical interpolation, which uses samplepoints to estimate values for points of unknownvalue.

2 Sui has advocated the emerging third culture ingeography in which state-of-the-art technologyserves to generate and meld creative ideas from thearts and sciences (Sui 2004).

3 Recently, I was asked to create a quick and dirtythematic map for a conference presentation slide.

Although the map focused on the northwesternUnited States, the display showed a portion of Can-ada. Unfortunately, my readily available digital spa-tial data did not include Canadian rivers at as high alevel of detail as the U.S. rivers, and I was reduced tousing suboptimal data. Given these constraints, theresulting map may well provide fodder for dec-onstructionists even though there was no hiddenagenda in my less-than-hoped-for portrayal of mygrandmothers country. In contrast, when I workedfor a transportation agency some years ago, mappers

were often advised to massage the numbers toproduce maps favorable to the cause of the moment.4 Caliper Corporations Maptitude offers the option of

automatic, equal area projection (Caliper Corpora-tion 2004).

5 For example,IDRISI, developed at Clark University,includes built-in functionality for uncertainty man-agement (IDRISI 2004).

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ELAINE J. HALLISEY is now the Director of theGIS Team at the Office of Health Information andPolicy, Division of Public Health, at the Georgia De-partment of Human Resources, 2 Peachtree Street,Suite 15243, Atlanta, GA 30303. E-mail: [email protected]. Her research interests include carto-

graphic visualization and the application of GIS tech-nology and analytical techniques in both human andphysical geography.


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