ReliefPresentationonUSNationalParkServiceMaps

TomPattersonUSNationalParkServiceHarpersFerryCentertom_patterson@nps.gov

Chapterexcerptfrom:MountainCartography.16YearsICACommissiononMountainCartography.http://carto.univie.ac.at/index.php?id=194016IntroductionThischapterexaminestheevolutionofreliefpresentationsonmapsdevelopedbyHarpersFerryCenter,themediaservicecenteroftheUSNationalParkService(NPS).HarpersFerryCenterproducesstandardized“Unigrid”brochures,whichincludethemapsusedbyparkvisitors.Whatfollowsisageneraloverviewoffiveparkmaps,eachwithadistinctivereliefstyleandmodeofproduction.Theyappearinroughchronologicalorderoftheirdevelopment.Recentreliefpresentationsaregenerallymoredetailed,colorful,andrealisticthanthosefromearlieryears.Changingtechnologyislargelyresponsibleforthedifferentreliefstylesfoundonparkmaps.Somerelieftreatmentstodaywerenotpossible,orimaginable,in1977whentheNPSestablishedthebrochureprograminitsmodernphase.Landscapeheterogeneityisanotherfactorbehindthedevelopmentofdifferentreliefstyles.Withover400parksitesrangingfromtheglacialmountainsofAlaskatotherollingpiedmontofVirginia,aone-style-fits-allapproachcannotadequatelydepictalllandscapes.NPSmapsservesome300millionparkvisitorseachyear.Ourongoingefforttomakeunderstandablemapsforthisdiverseaudiencehasfurtherspurredexperimentsinreliefpresentation.ThereliefpresentedonNPSmapsisgenerallynotasimportantasvisitorinformation:pointsofinterest,facilities,roads,trails,etc.Toreflectthiscontext,thereliefexamplesthatfollowareexcerptsfrompublishedparkmapscontainingallclassesofinformation.Theyarealsoexclusivelyplanimetric,sincedelvingintotheintricaciesof3Dreliefpresentationiswellbeyondthescopeofonechapter.

Map1:ManualShadedRelief

Figure1.DinosaurNationalMonument,UtahandColorado,featuringanairbrushedshadedreliefbyBillvonAllmen,1983.Over35yearsagowhentheNPSUnigridprogramlaunched,oneofthemaingoalswastobringparkmapsoutof“thedarkagesofline-workcartography”accordingtoVincentGleason,thenChiefofPublications(Hanna,1988).Hisvisionwastorepresentterrainonmapswithuser-friendlyshadedreliefinsteadofhachuringorcontourlines.UnderGleason’sguidance,RRDonnelleyCartographicServices,thefirmhiredtodevelopparkmapswithanentirelynewlook,producedthefirstshadedreliefmaps.Soonafterwards,theNPStappedcartographerBillvonAllmen(1928-2013)tobethein-houseshadedreliefartist(Figure1).HespentsixweekstrainingattheSwissFederalOfficeofTopography(nowcalledswisstopo),andthenwentontoproduceover80shadedreliefsbeforeretiringin1990.TomPatterson,hiredin1992toreplacevonAllmen,hand-drew12reliefspriortoswitchingtodigitalproductioninthemid-1990s.ExamplesfrombothartistsareavailableontheShadedReliefArchivewebsite(seereferencesforURL).VonAllmen’stoolofchoicewasthePaascheABairbrush,withwhichhesprayedamistofinkonmetalmount,atypeofpaperadheredtoanaluminumsheetfordimensionalstability.Heworkedfromcontourlinesappliedtothemetalmountasa

temporaryblueemulsion.Asalaststephewouldsprayammoniaonthecompletedarttoremovethecontours,withoutdamagingtheairbrushwork.Bycomparison,Pattersondrewreliefswitha4HpencilonDupontCronaflexUC-4draftingfilm.Thericestarchsurfaceonthisfilmwasreceptivetosmudgingwithstumps,finelypointedsticksmadefromrolledcardboardthatabsorbgraphite.Acontourbasemapcouldbereadthroughthetranslucentdraftingfilm.Byslidingawhitesheetofpaperunderthedraftingfilm,Pattersoncouldseetheshadedreliefhewasdrawingwithoutthecontourlines.Regardlessoftheproductionmethod,creatingmanualshadedreliefwasslowandpainstakingwork.Alargeparkreliefcouldtakeonemonthtocomplete.Manualshadedreliefoftenappearshighlygeneralizedbecauseaddingdetailandrefinementtotheartrequiresevenmoretime.Giventhegreateffortthatwentintocreatingmanualreliefart,thenaturaltendencywastofeatureitprominentlyonearlyNPSmaps,evenifitinterferedwithotherinformation.Printingoftheshadedreliefbecamelighteronsubsequentprintings.Onatypicalmapfromthaterathereliefwouldprintinblackandcombinewithflatareacolorsbuiltfromcyan,magenta,andyellow.Halftonescreen-printingwouldcontrolshadowdensitiesontheshadedrelief,simulatingcontinuoustones.Thedensestshadowswere15percentblack,flatareas4percent,andhighlights1percent.DinosaurNationalMonumentisoneofthefewremainingNPSmapsthatstillemploymanualshadedrelief(Figure1),althoughadigitalversionwillreplaceitin2015.Shadedreliefscreatedmanuallyreflectindividualartisticstyles,andtheyvaryinappearance(Figure2).Ifanartisthadtoredrawareliefofthesamearea,thesecondversionwouldlookslightlydifferentfromthefirst.Ontheotherhand,NPSshadedreliefartexhibitscommontraits,regardlessofwhodrewit.Modulatedlightandshadowscreatetheimpressionof3Dterrainonaflatsheetofpaper.Theilluminationsourceisfromthenorthwest(upperleft),andprominentfeaturesreceivemostemphasis.

Figure2.Manualreliefexamples:(Left)HotSpringsNationalPark,Arkansas,byRRDonnelley.(Center)GrandTetonNationalPark,Wyoming,byBillvonAllmen.(Right)CityofRocksNationalReserve,Idaho,byTomPatterson.

Map2:DigitalShadedRelief

Figure3.DigitalshadedreliefofOlympicNationalPark,Washington.Theswitchfrommanualtodigitalcartographystartinginthe1990srevolutionizedNPSshadedreliefproduction.Whathadbeenthemostdifficultmapelementtoproduceeventuallywouldbecomeoneoftheeasiest,reducingproductiontimeforabasicrelieffromafewweekstoafewminutes.Theswitchtodigitaldidnothappenovernight.Inadequatesoftware,lackofanintegrateddigitalworkflow,andpoororunavailableelevationdatahamperedearlyproductionefforts.Forexample,USGSdigitalelevationmodels(DEMs)fromthattimesufferedfromterracingandstripingartifacts,whichyieldeduglyblemisheswhenrenderedasashadedrelief.Inaddition,thevalleybottomswereoftenoutofregistrationwithdrainagelines.UsingtheseflaweddatatoproduceabarelyacceptableshadedreliefrequiredhoursofeditinginAdobePhotoshop.Itwasoftenmoreconvenienttoscananoldmanualshadedreliefforanewparkmapotherwisemadefromdigitaldata.Nowadaysthesituationismuchimproved.TheNPSusesNaturalSceneDesignerProsoftwaretoefficientlyproduceshadedreliefsfromartifact-freeDEMsacquiredfromtheUSGSNationalElevationDataset.

TheNPSinitiallypresenteddigitalreliefonmapsinthesamemannerasmanualrelief,lightlyprintingitasbackgroundblack(Figure3).Incontrasttomanualshadedrelief,afrequentproblemwithdigitalreliefisexcessivedetail(Figure4).TheDEMsfromwhichthereliefderivesoftencontainmoredetailthanthatnecessaryonavisitormap,inadvertentlyproducingvisualnoise.TheNPSalleviatesthisproblembydownsamplingDEMspriortorenderingshadedreliefs,thenapplyingthemedianfiltertotherenderedartafterwardsinPhotoshop.Themedianfiltereliminatessmallterraindetailswhilepreservingthelargerfeatures.TerrainSculptorsoftwareisanothermethodusedbytheNPStogeneralizeDEMsbeforereliefrenderingtakesplace(Leonowiczet.al.,2010).TheNPScompletesashadedreliefbyaddingcontrastathigherelevationstoincreasetheapparentthree-dimensionalityofmountains.UsingagrayscaleDEMasaPhotoshoplayermaskandapplyingextratonetomountaintopshadowsaccomplishesthisenhancement.TheaerialperspectiveeffectdevelopedforSwisstopographicmapsisthebasisforthistechnique(Imhof,1982).Arecenttrendistoprintdigitalreliefincolorsotherthanblack.Forinstance,usinglightbeigereliefforasouthwesterndesertparkevokesanaridenvironment.Beigereliefalsointerfereslesswithblacktypeandsymbols,improvingoverallmaplegibility.Printingshadedreliefsincolorsthatmimicthenaturalenvironmentintroducesthenexttopicofthischapter,naturalcolors.

Figure4.OlympicNationalPark,Washington.(Left)ManualshadedreliefcreatedbyBillvonAllmen.(Right)Digitalshadedreliefrenderedfroma90-meterDEM.

Map3:NaturalColor

Figure5.KenaiFjordsNationalPark,Alaska,innaturalcolor.ThepopularizationofnaturalcolormapsstartedwithUSGScartographerHalShelton(1916-2004).Workingonhisowntime,Sheltondevelopedaseriesofroutemapsforairlinepassengersduringthe1950sand60s,whenairtravelwasfirstbecomingcommonplace(PattersonandKelso,2004).Hebelievedthatforhismapstobeeffectivetheyshouldusecolorsresemblingthosethatpassengerscouldseeonthegroundbelow.Withtheassistanceofateamofacademicgeographerswhocompiledlandcoverinformationonbasemaps(Earthmonitoringsatellitesdidnotexistthen),Sheltonpaintedbeautifulandrealisticmapsusinganaturalpalette.Ifanareawasconiferousforest,hepainteditdarkblue-green;ifitwasdeciduous,mediumgreen;grassland,lightyellow-green;andsoon.Shelton’sapproachtomappingwithcolorsfoundinnatureseemedapplicabletolargeexpanseslikeKenaiFjordsNationalPark,Alaska(Figure5).UnlikethetraditionalmapofDinosaurNationalMonument(Figure1),whichemploysanarbitrarycolorchoice,flatgreen,thevaryingcolorsontheKenaiFjordsmaphelpusersbetterunderstandlandcoverandtherelatednaturalenvironment.

Creatinganaturalcolorparkmapisaccomplishedwithrasterlandcoverdata,suchasNationalLandCoverDataset(NLCD),availablefortheentireUSat30-meterresolution.Likepaintingbythenumbers,butusingpixelsinstead,thegarishcolorsoftheoriginallandcoverimageareswappedforanewpalettederivedfromnature(Figure6).Landscapephotographsavailableonpopularonlinesitesareagoodsourceforappropriatenaturalcolors—colorselectionisasimplematterofsamplingthemwiththe“eyedropper”toolinPhotoshop.Subtlecolorsworkbest.Inaddition,atlargermapscales,assigningorganictexturestothelandcovercolorsproducesamorerealisticappearance.Forexample,theKenaiFjordsmaphassubtletexturesrepresentingtreecanopyandglaciersurfaces.Asafinishingtouch,standardshadedreliefilluminatedfromthenorthwestdefinesthetopographicforms.Naturalcolormapsareasynthesisofsatelliteimagesandshadedreliefmaps.Althoughnaturalcolormapsoftenlookrealistic,theydifferfromaerialimagerybywhattheylack—haze,castshadows,clouds,andunneededphotographicdetail(Patterson,2002).Theyareessentiallyreconstitutedsatelliteimagesoptimizedforcartographicdepiction.Naturalcolormapsarenotwithoutproblems,however.Thenaturalworldcanbedisorganizedanduntidy,andsotooaresomenaturalcolormaps.Iftoohighlytexturedandboldlyprinted,overallmaplegibilitycansuffer.Andnaturalcolormapsdonotcombinewellwitharbitraryareacolorsrepresentinglandownership.Itisbesttodepictpropertyparcelswithsimpleboundinglinestoavoidcolorconfusion.

Figure6.KenaiFjordsNationalPark,Alaska.(Left)NationalLandCoverDataset.(Right)Naturalcolors,textures,andshadedreliefappliedtoNationalLandCoverDataset.

Map4:TextureShading

Figure7.GlacierNationalPark,Montana,withrocktexturesappliedtosteepslopes.TextureshadinghasbecomeacommonelementofNPSreliefpresentationssincethe2010introductionofthetechnique(Brown,2014).TextureShadingisproducedbyTerrainTextureShader,softwarethatdetects,amplifies,andrendersslightvariationsinDEMsasimageswithincreasedcontrast(Figure8).Byitself,textureshadingistoodarkandcontrastingtohavecartographicutility.Butwhenmergedwithshadedrelief—therecommendedproportionsare60percentshadedreliefand40percenttextureshading—itenhancestheshadedrelief.Theadditionoftextureshadingrevealssubtledetailsonilluminatedslopesandinflatareasnotevidentontheoriginalshadedrelief(Figure9,center).Themergedresultshaveaflattertonalrangethatworkswellasabackgroundonmapsfilledwithothertouristinformation,especiallywhenthereliefislightenedandcolorized(Figure9,right).Textureshadingismostbeneficialinlow,irregulartopography,likeglacialdepositsanderodedbadlands.

Figure8.GlacierNationalPark,Montana.(Left)AgrayscaleDEM.(Right)AtextureshadingcreatedfromtheDEMatdefaultsettings.

Figure9.GlacierNationalPark,Montana.(Left)Shadedrelief.(Center)Mergedshadedreliefandtextureshading.(Right)Themergedresultslightenedandcolorized.Mountainlandscapesalsocanbenefitfromthetextureshadingtechnique,whichcanyieldacceptablerocktexturesfromDEMsunderidealsituations(Patterson,2014).Mountainswithhorizontalrocklayers,suchasthoseatGlacierNationalPark,Montana,arebestsuitedtothetechnique(Figure7).Toproducerocktextures,onefirstmustrenderatextureshadingwithmaximumdetailandcontrast.ThisvisuallynoisyimageisthencombinedwithashadedreliefmadefromthesameDEMinPhotoshop,andwithaslopelayermasktoapplyitonlytothesteepestslopes.OtherenhancementstoGlacierNationalParkmapincludegreenlowlandhypsographyinthedeepestvalleys,yellowsunlightonilluminatedslopes,andcomplementarycoolblueonshadowedslopes.Swisstopographicmapsinspiredthecolorscheme.

Map5:HybridGeospatialImages

Figure10.PetrifiedForestNationalPark,Arizona,featuringaLandsat8satelliteimagecombinedwithshadedrelief.AgrowingtrendonNPSmapsistheintegrationofgeospatialimages—satelliteimagesandaerialphotographs—withreliefpresentations.Theuseoftheseimageswasatfirstsparing.Forexample,naturalcolormapswereenhancedbyselectivelyborrowingglacierandforesttexturesfromaerialphotographs.Morerecently,theNPShasbegunusingimagesasthedominantcomponentinreliefpresentations(Figure10).Theincreasednumberofsourcesforfreeimagedatahasencouragedthisexperimentation.NationalAgriculturalImageryProgram(NAIP)andLandsat8aretheimagesusedmostoftenonNPSmaps.Usinggeospatialimagesinreliefpresentationsworksbestonlandscapeswithlowrelief,suchaslavaflows,braidedrivers,marshes,shallowwaterbodies,anddeserts.Forexample,themapofPetrifiedForestNationalPark,Arizona(Figure10)usesLandsat8,whichcapturestherichcolorsofthePaintedDesertandanetworkofdrystreambeds.Itgivesatruerpictureofthatdesertenvironmentbeyondwhatispossiblewithtraditionalcartography.Depictingthemanydrystreamswithconventionalbluelines,forexample,wouldimplymorewaterthanwhatnormallyexists.Landscapeswithlowreliefhaveanotheradvantageongeospatialimages:fewershadows.Shadowscastbythesunonlandscapesurfacesandembeddedinimagesareamajorproblemwhenmakingreliefpresentations.Thehighertheterrain,thedenserandmoreobscuringtheshadowsbecome.Acompoundingproblemisthelightdirectionongeospatialimages,typicallyfromthesoutheast(lowerright),

whichplacesshadowsonnorthwest(upperleft)facingslopeswhenimagesarenorth-oriented.Theresultis“terraininversion”:Mountainsappearasvalleys,andviceversa.Removingembeddedshadowsfromimagesisnotfeasibleinmountainousterrainwiththedensestshadows—moredamagethangoodresultsfromimageeditingprocedures.However,onimageswithlowrelieforlimitedareasofhighrelief,shadowremovalisaworkableoption.Thebestimagestousearethosetakenaroundthesummersolsticewhenthesunishighestandshadowsareshortest.Afterremovingtheshadowsfromthegeospatialimage,onecanthenmergetheimagewithconventionalshadedrelieftocreateahybridproductwithpositivetraitsofboth;shadedreliefthatreadsproperly,plusrealisticandattractiveimagetextures(Figure11,right).TheNPSremoves,oratleastneutralizes,embeddedshadowsfromimagesusingtwoAdobePhotoshopprocedures.Thefirstprocedureworksbestonimageswithlightormoderateshadowdensities.ItinvolveslighteningtheshadowswithaBrightness/Contrastadjustment.Toselecttheshadowstoapplythisadjustment,onemustfirstcreateashadedreliefmaskfromaDEMofthesameareathatmatchesthesunangleandazimuthoftheimage.ThemetadatafileaccompanyingLandsat8imagesprovidesthisinformation.Thesecondprocedureappliestoimageswithboldshadowsthatcompletelyobscurelandsurfacetextures.TheNPSselectstheseshadowswithPhotoshop’sMagicWandtoolandusesContentAwareFilltoautomaticallyreplacethemwithtexturesborrowedfromelsewhereontheimage.Thisprocessispotentiallyinaccurateandmisleading.Aftermergingashadedreliefwiththedoctoredimage,however,thebrightlyilluminatedslopesonthereliefcompletelycoverimageareasthatwereformerlyshadows(Figure11).Printingthegeospatialimagelightlywhenmergedwithshadedreliefalsoamelioratesthisproblem.Theobjectiveistoshowahintofimagedetailonallbutthesteepestslopes.

Figure11.PetrifiedForestNationalMonument,Arizona.(Left)ALandsat8imagewithembeddedcastshadows.(Center)ShadedreliefcreatedfromaDEMofthesamearea.(Right)MergedLandsat8andshadedrelief.

ConclusionTherelieffoundontoday’sNPSmapsreflectsanevolvingarrayofstylesandtechniques.Decidingwhichstyleofrelieftousedependsonmanyfactors,includingavailabledata,terrainandlandcovercharacteristics,mappurpose,andtimeconstraints.Forexample,creatinganelaboratenatural-colorreliefofGreatSmokyMountainsNationalParkinthesouthernAppalachianswouldservenousefulpurposebecauselittlelandcovervariationexists—theparkismostlywoodedfromvalleybottomtoridgetop.Abasicshadedreliefperhapscombinedwithtextureshadingcasewouldsufficeinthiscase.Recentlydevelopedstylesofreliefpresentationhavenotnecessarilysupplantedearlierstyles.Whilethe1970sand80sweretheheydayofmanualreliefshading,theNPSstillappliesmanualtouchupstodigitalreliefs—usingPhotoshopandaWacomtablet—tomeetdesignneedsnotpossiblethroughautomatedmeans.Forexample,theKenaiFjordsmap(Figure5)hasahand-drawnoceanbottombecausedigitalbathymetricdatawasnotyetavailableforthatareaatthetimeofmapproduction.Andsomenewermapscombinereliefpresentationstyles.CanyonlandsNationalPark,Utah,forexample,employsthreeofthestylesdescribedinthischapter(Figure12).Onthewhole,reliefpresentationonNPSvisitormapshaschangeddramaticallysincetheUnigridbrochureprogrambeganin1977,andcontinuestoevolve.Assoftwareanddataimprove,sotoowillthereliefpresentationsonparkmaps.ReferencesBrown,L.,2014.TextureShading:ANewTechniqueforDepictingTerrainRelief[presentation],9thICAMountainCartographyWorkshop,Banff,Canada.https://app.box.com/textureshadingHanna,J.1988.UpsandDownsofShadedRelief,Courier:NewsmagazineoftheNationalParkService,(11),23. Imhof, E. 1982. Cartographic Relief Presentation. Edited by H. J. Steward. Berlin: de Gruyter, 172. Leonowicz,A.,Jenny,B.,andHurni,L.2010.TerrainSculptor:GeneralizingTerrainModelsforReliefShading,CartographicPerspectives,(67),51–60. Patterson. T. 2002. Getting Real: Reflecting on the New Look of National Park Service Maps, Cartographic Perspectives, (43), 43-56.

Patterson, T. and Kelso, N. 2004. Hal Shelton Revisited: Designing and Producing Natural-Color Maps with Satellite Land Cover Data, Cartographic Perspectives, (47), 28-55. Patterson,T.andJenny,B.2010.ShadedReliefArchive[accessedDecember6,2014].http://www.shadedreliefarchive.com/nps-reliefs.html