Transcription
NYSGI-C-79-001".C. 3 IHIP'fvei444 akfL4 p NewYorkwasSeaundera grantfromSea Grant,NationalAtmosphericUS tionofbyInstituteCommerce.ofandNOAA!,
FORWARD:An undertakingtime years,Harpertheirof thisinvolvesmany participants.support.assistedininclude:Varda Wilensky,thisDoug citingfieldoutThe logicalto organizetwo and a halfI wouldforinformationartisticpresentand the PortRicklikepart-to thankand MarkstudyDavestructuresfrom itsexistencewho havein a veryand conclusionsare my own.licenseisIfPete Jackson,to the manycreatedshorta newperiod.The data used isit. stimulatesprimarilyI apologizeround holes,FellemanSyracuse,fromat theand excisingthought and discussion,worthwhile.Johnandwhich have been developedbending square pegs intocontext.who haveCase Study,Burgess,at best a "secondary" source.occasionallyforHolzman.owes itsof whole clothand former!Bay VisibilityDumont, Mollyand academicsthe materialpro]ect reports,StudentsJud,In particular,thecoveringand John Warbach of the School of Landscape Architecturecontinuedoutsetmagnitude,Summer l979
ingA Working ModelIII.DataIV.Viewshed nProcessesMovingVI.OutputPlan Views and PerspectivesVII.ConclusionsAssemblyAppendix AReferences
agementVisual3 inLandArtistPhotoRenderi.ng23.Digitized24.DMA Landform25.Digitizing26,Terrain27.USGS Le gendElevationsTruncationTransmissionPoint LightSource umVisibilityFactors8.Solar9.Seasonal Light28.PerspectiveOpenWater29.LUNRAreaandPointNYS taryr Viewsi e lCrestOverlookf- r«mSec t i onsand
Roadside59.Similar39.Triangles60.Topographic 48.50.ZonesView Angles67.68.Water Based View AnglesPREVIEW Terrain51.Slope52.Relative53.54.DriverOverlay Analysis MappingIllustrativePlot70.HighspeedPrinter Tonal56.TimesLine. PlotterCones72.View ConeSeenContinuousMapRoad maViewshedsand49.WinterWeighted OverlappingViewsRoadway Distance47.SketchtyOverlapping Viewsheds65.66,ExtentVis ib illView Or ientat ion VectorsDistanceView LinesSite- SummerSequence64.ofVisibilityPanoramic Photographic63.PointsEf fectsSiteField62.VisibilityHighway FilmstripRoadway Vis ib i 1ity74VisualMapGrid Perspective withDiagonal EnhancementHiddenLine Section Perspectiveperpindicu]ar to Line-of-Sight,PREVIEW SurfaceFeaturePlotComputer Generated Structures
sibilityProject81,NY Sea GrantTestCompositeMontageCellVisibilityMap
Visionhasbeenplays a centralestimatedthatrolein man's ourItsensoryGNVERO'NHf NTAL ME'5 C,RYLAND EvEAN49fMf NTegPEc. F E as been a majorevolutiondeterminantof human settlements.dominant PWTL Y5l5and physicalfortifications,and recreationsitedevelopment.The comprehensivecriticalmanagementstages of resourceofenvironmentalanalysis,resourcesland planningencompassesand projectdesign.-amre LEZED LOCATEOtISAND f'f P FORK,&'H C,E C-FETEREAfZZZ9As cation,1,each hese include:activitythesescenicallocations,can be sment,and performancewhich,inhuman .VisibilityV 'HEBE'LIT%whichvisIand cognitionFigurel: VisibilityinEnvironmentalLand management,
of landscapes.ofthisGeographictionintuitiveIn theremotesitetodevelopmentwas mapping evolved.The recentN.E.P.A.!observa-maps andsophisticated,off-momentum givenconcerns,by the Nationalhas led to the widespreaduse oftechniques.ofcoastalaestheticThe authorbeingbothresearchconductedrange of theoreticalfoundthatused by designthe publishedinaestheticainforma-terrainbecame available,particularlyActreviewed.to map visibility,calVisibilityas accuratestudies,clarityanalysis.century,methods were isionsdirectmappingtheand designby means ofYork Sea Grant Program, a widelackthe primaryin ironmentalsitingapproach to resourcemethods of visibilityInof theNewand projecta varietyand resourcedocumentationforofprofessionalsa widespreadand methodologi-approaches.Many ofdid notreflectthesestudiesappearedthe significanceoftobe underfunded,the information,resourcesexpendedand some were
clearlyisolatedIn contrast,some excellentvisibilityvatefrom or "tackedanalysesTo developbllltyb.thisstate-of-the-artstudy.appliedto emerge from the publicand pri-are threefold:conceptualconstructof landscapevisi-mapping;To systematicallycomplexand visibilityimprovedresourceThe body of thisa workingvisibilitying methods forVisibilitystudyVI,whilemethods of datamapping throughthe use of selectedintegrationisof visibilityand pro]ectpresentedwhileforIV is focusedstationarypositions;outputs,plan viewssome briefparts.visibilityof data assemblySectioninformationSectionmodel.on line-of-sightV forand perspectives,areidentifiedIIcontainsSectionthe elementsand Sectionconclusionsintodesign.in sixof a comprehensivea discussionmodel;the culateexamples;To fosterSedtionreporta coherent,illustratedIIIare esectors.The purposesa.on" to a moreof theprocess-moving observers.are discussedinSectionin
EN UIROWEI1PALH0DEL5 GHTLlf/E pROEESSf3
x 'vstj!RUTE9, oA.[l Gemanatesphysicsextentthefrompeoples have conceived of sightas a physicalthe2.the primitive"look"Note:at the stackintotheis truelightpoints,InareentersAlthoughmodernthe eye from externalanalysisfrom the adjacenta scaleon the model'swhichFig.for understandingA visibilitythe geographicof a smoke stackenvironment,three-dimensionalThe model is placed in a darkplacedinprocessor "look"surfacedirectlyroom, and a tinyat the positionilluminatedmodel of a realmodel,from reaching"interposition".5OLJRCrepresentlightsource isof an observer.thelocusofland-The surallvisiblethe "viewshed".theL/88 Tfromenvironment.!Consider buildingscape.as shownapproach is idealof visibility.stackfaceshuman eye,has shown the reversesources!could ooINTRODUCTIONMany primitivewhichXl&pF'[1M R-thethe darkIfFigureconfigurationhidden!we thenofareas.projectthesurfacesThis edvertically2:VisualTransmissian.
to a horizontalmap".Thisplane, we have constructed a scale "potentialisshown in Fig.The infiniteto "linesissueinlinesinvestigatedanalysisisBE ACROreducemanageableof the realtheA majornumber ofsuchset.the differenceenvironment.betweenA moremapping is shown in Fig.4.Each ofbelow.and surfaceTheyalsoprovideThe rolehas been extensivelyfeaturestheare the primaryvisualcontentof landformsexploredelements of inter-whichisin the contextin previousN.Y.thebasisof scenicforevalua-Sea Grant workl977!.LandformsVisuallyselectivelyis used above to clarifydiscussedscenery analysis.Felleman,to the environment.LANDSCAPELandformstionstomodel of visibilityelementspost.tion.isand the complexitiescomprehensivein the above example are analogousto a representative,The word "potential"therayspassing from observervisibilitythe simulation3.number of lightof atures.distancefromFi qnr»observer,location!.and aspectInlargeorientationseal ,ruggedrelativeto solarlandscapes,positionlandformstendand observertoprovide3:PointLi qhtSovroeHodel
VCwsHFDHAPVlC44HPQTblb5pflfKCLAND fOlt 8SNtFACfPFATUREsLA80P sNHTV&VNomeFigure4:VisibilityYodel .- R5ITFfRSPCCTlVE
the majorityficationlinesof interpositionof the visibilityof scenicas the scalerecord.Viewshed"FeaturesRegionalsurfacemodel utilizesand lyfeatureslandformsproperly5!oBcalledajpO4zand builtthe ionthe visual4VIzobserver,limitedincludedecreases,see Figureisitshave developedused simpli-landform,The latterto clarifystudiesincreasesA frequentlyPlanningofzW0S zC4D Wzand Designp.N-19!.In addition,fieldresearchregardingscaleand distance,indicatesz vrthatthedistancesignificanceincreasesFigures 6a, 6b!thatlandof surfacefeature"from foreground,Litton,developmentdecreaseto midground,1968!.typeswillas sight-lineto backgroundseeA New England highway study revealedcouldbe identifiedata maximumof1 kmW4jG.5 km mean! Jacobs and Way, 1969!.Ina significantcurvatureheightJuly,and lightof !.LandformsorientedwaterSeeare generallystudy.leW0zanalysis,thecombinationare shown to reduceobjectsalso0QXSee FigurediscussionstaticwithinA majorearth7!inofearthzzthe apparent0XRIIIX IJWVRoy Mann Associates,Sectionthe timeIV-D!.frame of a projectmoving projectwn»1d he anFi gure5:Lands a pe Con finu Um,
Figure6a:DistanceZones.Fi gvreFigure7. Vi si bi !i tgFactorsOpen Water.6b:Di s tance ZonesPerspective.
example of the exceptiondimensiontheishighlyseasonalment ofinstatement.theanalysissurfaceshort termofand landwouldfeatureHowever, the temporaltreatmentof vegetationvisualexpecteda pro]ect'srelevantattributesA comprehensiveto developmentchanges.a representativewhichstage,areand itsastreat-relevantduringlong-termusefullife. AtmosherevariableelementAtmosphereInand precipitationfeaturecharacteristicsvisibilitycan allvisibility.studies.modifyThisIsare a coattuuouslyLightingthe potentialimportantconditions,topographicto bothviewshed%pcclouds::0,:--.,'J's meOCand surfaceand scenicanalyses.A dramaticand nsAppleyardsun angle,is illustratedAesthetica frequentof Boston from ma!or highways in dayillustratesconditionsaspect,analysis6 Lynch,and observerin Figuresfieldfactoran e tremeresearchmodifyingexample1964!.positionofThe significancein viewing8 and 9 U.S.Foresthas shown thatcoastalon sitevisibilityc 'hc& vinovariableofsurfaceService,1972,haze and fogFelleman,1979!.Figure8:SolarPosition.
periodperiodSPRINGWINTEliFALLSUE! ghtVariationsMeanShadowLengthsFigure9:SeasonalLi ghtCandi CionsGeneral
C.OBSERVERAs notedearlier,a majorstudy is to effectivelyselectto be investigated.of theiror a combinationassociatedwithwhichgeneratethe fnew viewersa visibilityset of lines-ofmay be highlytheInaddition,analysisshouldFigurel0 depictsbecauseof the scene,Frequency of occurrenceobservers.sightsignificantthe unique contentand from the projects.is typicallyforincludeprojectsviewsof"views of the road"road".from activitypatternsand majorvehicularfunctionalcriteriascenic concern1974,viewsof occurrence,of theseina p.lg!.such as residentialroutes.The U.S.for analyzingrecreation,a Hudson RiverForestobservers:residential,In an analysispower ber, view duration,other!of proposed rvice,tower alternativesand weightedforresidential,Figureauto,rail,and boatzoneJonesand Jones, 1975! . Inof observersviewerswas factoredwithinby .thepotentiala transmission"An attentionviewshedlineanalysis,influencestudy,the numberwhich!addresses10:Vie "Of"Road.and"From"
how many ofthe potentialof the landscape."Carruth,be used as a design].970,viewersprinciplebe preoccupiedet al.,1977, p.32!.in providingwIthotherAttentionsequentialaspectsmay alsovarietyPragnell,p.38! .Uniue ScenesprotectionareaforfeatureResourceand sceneryof unique snd sensitiveexample,itmightfor potential,in the future.significantlandscapebe importantHxamples of visuallytops and eatures,Power Commissionparallelorientation,givento objectscombinedearlieststatedof a hillsilhouettedwithprotecta viewviewerspotentialthatwiththewildernessofa uniqueyears or nes,structuresnotl970!.to providevisualSee FigurecrossshouldPower Commission,degreezones.hill-points,of way shoulduse of skylinesthe sky.include:relatedand thatthe highagainstdealview Influenceenclosed alleys,is based on our perceptualstantoftenIn a remotelandscapeto the line-of-sight,not be placed at the crestThis logicto identifythemustcase viewsheds are mapped fromsignificantone oftosensitiveIn ionsthewillcontrastll!.con-
There is a generalgreatlyenhances the scenic qualityfeaturesoftenviews.featuresstudy,Litton,the adjacentuplandslopeswatersurfaceseeThe extended,waterunobstructedclassificationthe landscape unit,et al.,1974! . Thewhich are visuallyofsettinglatterrelatedinto12! .theValleyCommission had a flexiblewater-surfacehas been used in studiesviewshed.Fx9ure12:WaterinfluenceZone.Thisof the Potomac and Lake Tahoe,in federaland state,scenicalLypositivewildand sceniclegislation.EnclosurePotentialforis anotheropen viewswithinconcept in the classificationsee Figure 13!.Ross County,Ohioan enclosedlandscapevalleyof Nassachusett'sattribute.was a centralscenic highwaysThis concept has aIso been incorporatedof the Hudson Valleysee Figuresee FigureScenic turnouts,allof waterIn addition,a hierarchialN.Y. Hudson Riverand has been incorporatedriverforwas proposed:unitthe presenceof a view.opportunitiesand waterscapecludestheprovideIn a comprehensivewater-relatedunit,consensus thateni!anced E!y location14a!14b!recreationat pointsin ils,inand residentialthe terrainandsitesarewE!erc broad vistasF!. gumj.3!F,n . josureWas "ae.E! Use t ts
FigureFigurel4m: F,'no!osure145:RossCountyOhio.Hud on Pal.ley.f4
arevideavailable.Inruggedmaximum views;maximum viewswhiletendSee Figurepositionpositionrelativetomorewherepeaksand ridgelinesoftenlogicallymatureforms,steepand crowns.sidelandslopesend atSee MilitaryCrest,pro-thebaseSection15.!andviewerinto occurof the rounded terracesIV.!terrain,MotionViewshedand motion.andviewcontentThree prototypicalarefunctionsofviewe positionsFigurefied:SeethesuperiorFigure16!A matrixaidinthein The relationshipsextensivelysafety.studiedUnlikethe stationaryThe conceptimpactbeenl5.VistaPoints.identi-and inferiorbelow!.analysiszones ion and visibilitypositionhave beenof ground and airwhich is typicallytraffic0 5flgf P NOSÃhLpre-viewshed, medium and high speed motionthe normalofscene have.from the perspectiveshas been shown to limitdriver.theand distanceof viewersumed to have a 360o potentialthep.7!scenic1974,ofintermediate!,of viewer postionsselection17compositonviewcone of urel6:o55e5YfaSUPERI'Viewerposi tio s.
ObservercontainernaturalEnvironmentvehicle,and builta loca&.zeditbuildingis analyticallywhichMany impact"defoliate"visibilityIn addition,lineconditionroadsideinstudieshedge whicharenow incorporateorientationI ftDDtfSROa/fn4Acakale40as d Vleugnint DiatributiOn:NaturalDraft Cooling Toner Alternative O 2 FinalVieuscapes Required!.and scaleand macrolandscapes.map may correctlyexample,midgroundthe map may not have any indicationof a singleeffectivelyfrom the route.or filtersviewssky-Niddleground1/2-5 nilesbackground 5 lineationThesemethodsmay be generallyand lForeground0-1/2 Milesa foresta hillsideblocksdefineForObserverInferiorDistanceof data needs may be veryFi pure17;Vi elarer/Di StanceDi strD.S hfdfdesignmay not be visuallyas wellZ b 31g sbblxaNusbobjects.are oftenas windowinc5 tewhiledetailthesesurfaceview "f iltering"the accuracymass on a topographicLandscapebothand the immediateconceptuallyBecause thesesolid,includesany,and immediatemay be studiedmay occur.ifto differentiateplantings,forMacrocontainersopaque or continuouslydifferentAlthoughtheusefulBoth observerand rior
approachesare the traditionalincludethe use of stechniquestoexpandviews".Modern adaptationsand balloons,thescopeas welland contentas aps by means of crosssections,and the use ofterrainmodels utilizingorsources.pointlightductionvectorsa numerical Recordinmat whichThex,y,z!locusis compatibledata needs.Limitsperspectivescontent,the resourcerespectively.whichItisbetween moving and stationaryopticsdescribedutilizeinmust be recordedanalysis,computerstoin s for-planning,planthe viewshedor designinthe land-view maps andlimitsin processingand viewdatato articulateso that subsequent interpre-For example,views,intro-observer positionsMore nterpretation,modelmay be recordedof view limitfounded.photoof the macro landscape.of-sightof markers.are preparedare properlywas brieflyof lineswithboth the type and qualitytationsperiscopeapproximationof topographicairfrom the selectedof visibilityscape by the placementstereoNumerical simulationsto "pass" line-of-sightinterceptverticalThe lattersee Figure 3!.interpretationrecordingthe presenceshoulddifferentiateor ahsence of seasonal
ion.such as filtering!,"soft","ambiguous" ! ofThe latteris illustratedComputerized resourceof visibility.typically ,of "weightedthe area of view,distance,slope/aspect,see visible,are highlyinputsnot visible!scores" whichin-and number and typesAlthough mapped visibilitycomputer formatscenes due to the ease of reader18.requirematricesto the interpreter,Associates,in Figuregeographicof observersor tapes.studiesthe viewshed limitThese can range from a singleto sophisticatedcorporateand the geographicis typicallyusefulin illustratinglegibilitysee Figureis usefultabulatedcardsthe content19!ofRoy Harmb,M5 p EQT'lVE'Figure19'Plan/Perspective.Limit
ENYIROAHENTIL 800EL
A.INTRODUCTIONThe macro landscaperequiredata.the onofi.e.,informationproject.is highlyusefulbePRINARY DATA Dataofterrainthe data isof. the visibilityaud surfaceof-sightcompatiblemodelcharacteris also significant.from otherin discussingdataIn thisThiscomponentsto clarifyforin form andprocess to be utilized.gatheredenvironment.willcomponentsstage of study design is importantthatconsistencyanalysisto the actualdefinitionsto thisthe subsequent lineexternalthe sharingresourceand synthesisconsistency,withand observerInincludesoftbeitsrelationshipmonograph the followingfunctionalused:collectedinthe field.Examplesincludephotographs,sketches, map notes, videotapes, and position marking such as flagsandstakes.
SECONDARYDATA Information,axXresslstudy.airfor the vtsualAn example ofphotos; whileas the U.S.G.S.visual7Q minuteInventoryARAAThisforgeographicet al.,pointmap made fromtopographicmaps suchwouldnot expresslybe soilsurveys,Land Use and Natural.processedsecondaryhas been manipulatedforExamples are thegridtopographicmaps,fromof terpretedcellsand tertiaryinclusioncellin digitalcentroidand heightfrom airdata.elevaandphotos and storedin the EDAP studyLandscapes1973!.PENTENARYDATA NumericallyslopeinformationExamplesanalyses.Q diversitydata seed of theL.U.N.R.!.informationtionsis a forestwould includeand New York'sAcomputermapped, which has been processedor for a directthe formerstudies.designations,study,the latterTERTIARY DATA Mappedfortypicallyhybridquarternaryand aspect maps generated1975!,elevationsand gridcellSampson,from gridelevationsdata.cellExamples includeelevationsdevelopedTravi.s,f rom "random"1978! .20
ndscapeand Observerbe addressedfromand e.H.LANDFORMThree dimensionalfactorinviews1.largephysiographyand mediumof backgroundlandscapesand midgroundthe s!. Pr marPrimarygroundlevelterraindata may includephotographywere the edsupplementedofscaleis usuallyterrainFigure19!and verticalaerialmeans of recordingAn example ispositionorobjectthe need to manuallyby notesfeaturestopographicas experiencedsee Figure21!Litton,photography.landfeaturesshown in Figurelocation!portraycan be highlysurveys,1973,Litton,features,in highlightingand photographedp.21! .sketches,Fieldsketcheson maps by ex-photographydetaileduseful20field1973,p.3!.has largelyfieldsketchesthe characterin the fieldseeFiqure20:DetailedFieldSketch.
OSIGHTTIAZIINUICLAREMONTQNMl,4tiiIELDTH3 MI.Figure2I:PhotoPlan STANCESARENOTI.E.NOSCALE' Distance diagTTTnTReferenceSketch
eeSectionaerialphotographyprofilesRegulatoryisand skylines,Commission,1973; Aerospacea ngs1977!seeand computer1977; Penzien,1978,photographssuchinstereopairsas landslides,canbe usedreservoirtoupdateconstructionmining. Seeondarterrainsurfacetopographicinformation.of identicalsurfaceAnalystsphotographyand interpretation.Insome studyavailable.graphy.shouldlocationslines1" 20',yearsOne of50'todetailedmany advancesthe laceofinmajorthethe "orthophotosourceon the groundto nationaldatesthe vicinitythepointsare plottedbe sensitivemaps forwithconnectingelevation!moreanalystsFor example the New York Statehas developedrecentmaps provideContoursstandards.InGroundisscenic impacts using artistchangesThe U.S.G.S.ofofphotographyIV!.topographicand surface2.NuclearCalhoon,Verticalmajoranalysisand after"U.S.location!technique.directtion of .maps may beof ",the plotting
ProjectedView of 565-FootTowersFigur'e22;AristFhoCu R .i dc.ri tt r.
ofpertinentterraincorrectedairitsnationwide3. TertiarWhereand culturalphoto mosaic.informationThe U. S.G. S. ison a distortionintroducingthesemaps inmap rficialdefinesoilgeologyvisuallysurveymaps arerelevantreadilyIandforms.maps appeartobe ithsiderablethe adventresearchdata banks ofcartesianAtinterestterraincoordinatessectionor cellpresent,of digitalinformation.withonlyNapping as been devotedsee SectionIV!to the heseelevatIonsincludeforcon-of digitizeda matrixeach gridofinter-see Figure 23! .widelyavailableterraintapes which are a d of the U.S.maps.Ground cellsFigureare 200'squareNationalThe suitabilityfunctionofthe scaleCartographicof thisInformationinformation.of the projectarea,forvisualCenter!.analysesis aand the degree of resolution23:DigitizedElovations.
required.Inan innovativeused to establishthe D.M.A.and 100',320'scenicthe "scenicinformationboundary"the studyThis"V" shaped f 400'reliefofthewereSincehorizontallyconservativeby a trapezoidthe N.Y.tapesto map 400 acre unitsapproach was consideredIn contrast,D.M.A.the Upper Missouri.was designedis approximatedDyke, 1977, p.7!.study,has a maximum deviationvertically,square!.riveras asee FigureAC24!VanSea Grant Port Bay Case StudyI:250,000maps withinternallyrepresentcost,maps, edatacoastalareasdecisionsto inputa gridprocessService,and software,forSincegrids,ofconvertingcompatible1978! .manysubsequentmost analysesmust be made regardingquarternary!program from non-gridto a computerForesthardwareroutines.with a softwareiscomputertoterrainand whethera gridofnow rialcards,or DHA ImndformTruncation.
hicand areascurrentlypolygons!,availableforand eitherorsuperimposingmanuallya gridrecording,centroid!elevations.data can be developedin variouson thedataor electronically Pentenarpointseitherin associatedwithintopoints,oftoand output,entailspointusefulmodel base ininformationisanalysis,can be grouped2S depictsitand a numericalcoordinatesalongeach lineargridAn analyticallydimensionalrandom or othe contours,withCorp.,approximatecontourscan beone z elevationp.5-1!.representingitrun to createsubsequent transformation1977,means of"Random"can be digitizedprogramSampson, 1978, p.91! . Lineara numericalways.witha finitea threenumberof27
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facets,each withinternallyapproachis widelycomputergraphicformanalysisutilization.see Figurecan be made by ies!,par t IV!made forcornercurvatureterraininterpositionto1973,A computer-derivedsurfaceofthe projectdistanceautomobile. Inslope,andlandaspect,numericaldata bankofareasoutlinewithThiseach areafacetWagar,1977!.FEATURESThe ics.designNewman, Sproull,a growingand associatingsurfaceused in industrialshadingand tures,studyareaAs the scalepositionsincrease,vegetation,shouldbe carefullyof aceFi uvrefeaturesl.in definingmacro landscapelimitsof visibi1itydiminishes. Pr1marFieldmeans deand f ieldphotographycomprehensivesurfacemay be encounteredtocontrast,a topographicverticalthe most significantinbaseairare generallycovertranscribingan inef f rticularlydata source.Note,stereohowever,pairs!thatl leldcliecks26. TerrainFacets.
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a pro]ect's short term implementation stage, and its long-term useful life. Atmos here Atmosphere characteristics are a coattuuously variable element In visibility studies. Lighting
