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Transcript of Airborne LIDAR for Obstruction Mapping: Enabling Flight · PDF fileAirborne LIDAR for...

  • By Bill Gutelius

    Airborne LIDAR for Obstruction Mapping: Enabling Flight SafetyKey points

    AirborneLIDARisaneffectivetoolforcollectingairspaceobstructiondataatairfields,leadingtosaferairspacenavigation

    TheFAAhasrecentlyadoptedLIDARasakeytechnologytobeutilizedinthedetectionandmappingprocessofobstructionsaslaidoutin(draft)AC150/5300-17C

    Furtherdevelopmentsareintheworksandresearchcontinuestorefinetheefficienciesofoperationandtheaccuracyofdatacollected

    IntroductionAslaserscanninghasevolvedandmatured,ithasincreasinglybecomeanewandeventuallynecessarytoolinmanyindustries.Oneareathathasbenefittedfromtheapplicationoflaserscanningisaviationsafety.AirborneLIDAR(LightDetectionAndRanging)isusedtodetectandmapobstaclesthatintrudeintotheairspacethroughwhichaircraftfly(Figure 1).Ground-basedLIDAR(mobileandstaticscanningsys-tems)technologyalsohasrecentlybeenusedtomap/imagegroundobjectssuch

    astaxiwaysignage,lightingfixtures,weatherandcommunicationsstruc-tures,aidstonavigation(NAVAIDS)andothermanmadeandnaturalfeaturesonandimmediatelyadjacenttotheairport.Additionally,thereisgrowinguseofmobileandstaticscannerstoimageandmapairportinfrastructuresuchastheinteriorandexteriorofairportterminalsaswellasapron,baggage-handlingandotherancillarystructuralfeaturesfoundatanairfield.

    TheapplicationofairborneLIDARtoobstacledetectionandmappingprovides

    Figure 1 Scanning to detect and geo-reference terrain and surface obstructions, from NOAA Aeronautical Survey Program, SOW for Airport Surveying, 2010 and FAA NAS Implementation ANA Survey.

    Displayed with permission LiDAR Magazine Vol. 2 No. 1 Copyright 2012 Spatial Media www.lidarnews.com

    http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/nas/procedures/index.cfm?print=go

  • criticalinformationforflightsafetyastheFAAusestheinformationtomakedecisionsaboutflightproceduresatandaroundtheairfield.Inadditiontomappingobstructions,airborneLIDARutilizationprovidestheairportoperatorandtheFAAwithdetaileddataforinputtoairportlayoutplans(ALP)andgeographicinformationsystems(GIS).TheFAAsetsoutaguideforcontractorsandsponsorslookingtofulfilltherequirementsforthesesurveysanddatacollection:GuidetoAirportSurveys.

    FAA and LIDARSafetyofflightisanobviouslyparamountconcernoftheFAA(14CFRPart77,updatedJuly21,2010;Safe,EfficientUseandPreservationofNavigableAirspace).Oneaspectofensuringsafety(avoidanceofflightintofixedobjects)toalllandinganddepartingaircraftrequiresdeterminingthelocationofobstacles(sometimesreferredtoasobstructions)locatedintheairspacenavigatedbyaircraft.Specifically,thegeo-positionsoftheobstructionsareevaluatedagainstavirtualsurfacetodeterminewhethertheypenetratethe3DareaknownasanObstructionIdentificationSurface(OISalsosometimesreferredtoasanintrusionsurfacehttp://www.ngs.noaa.gov/AERO/OIS/ois.html).Figure 2,depictssuchanOIS,whichmayhaveasmuchasa40:1or70:1sloperelativetotherunwayandtypicallyincludestheairfieldandapproaches.

    TheOIsurfaceprovidesalimit(plusasafetymarginCFR77.19)towhereaircraftmayoperate.Theintegrationof

    thevarioussurfacescanbecomplexasseeninFigure 2.Obstructionsconsistofeverythingfromterrain,buildings,towers,poles,antennasandtreestoimpermanentstructuressuchasconstructioncranes.FlightproceduresarethendevelopedforaircrafttoavoidtheobstructionsusingFAAobstructionevaluationrequirements.TheFAAspendsmanyman-hoursdevelopingairportobstructioncharts(AOCs)andotherproductssuchaseALPsthatultimatelyallowpilotstoavoidtheseobstaclesandflywithconfidenceandcertaintytoandfromairfields.

    Currently,theFAAreliesonanAdvisoryCircularprocess(AC)regardingairportsandactivitiesaroundtheairport.Specifically,AC150/5300-17Bwhichaddressestheuseofremotesensingtechnologiesincollectingdatadescribingthephysicalattributesofanairfieldandrelated.TheseACsguidetheusersintheacceptablemethodsandstandardsinthedatacollectionprocesswhileemployingremotesensingtechnologies.

    Untilrecently,LIDARwasnotconsideredan(officially)acceptablemethodtocollectgeo-dataregardingobstructions.WhilemanycontractorswhoweretaskedwithprovidingobstructioninformationfortheFAAtoincorporateintoflightproceduresandaeronauticalchartsactuallyemployedLIDAR,theyhavenottypicallylabeleditasLIDAR-derived.Rather,thecontractoronlyneedstosubmitalistofobstructionsandtheassociatedgeo-coordinatesandfeatureattributes.

    In2011,followingmorethanadecadeofresearch(someofitinitiallysponsoredbyFAA)adraftversionofthereplacementAC(AC150/5300-17C)wasreleasedforreview.InthedraftAC,thereisnew,detailedlanguagespecificallyconcerningtheuseofLIDARasaremotesensingtoolforthecollectionofgeo-dataaboutairportobstructions.Inadditiontothehistoricaluseofaerialimagery,LIDARisnowdescribedasanothertechnol-ogywhichairportsurveycontractors

    Figure 2 ANA Surfaces at Frederick Airport, Maryland. Courtesy Dr. Chris Parrish, NOAA-NGS.

    Displayed with permission LiDAR Magazine Vol. 2 No. 1 Copyright 2012 Spatial Media www.lidarnews.com

    https://airports-gis.faa.gov/public/data/Airport_Survey_White_Paper.pdfhttp://www.ngs.noaa.gov/AERO/OIS/ois.htmlhttp://www.ngs.noaa.gov/AERO/OIS/ois.htmlhttp://www.faa.gov/airports/resources/advisory_circulars/http://www.faa.gov/documentLibrary/media/advisory_circular/150-5300-17B/150_5300_17b.pdfhttp://www.faa.gov/documentLibrary/media/Advisory_Circular/draft_150_5300_17c.pdfhttp://www.faa.gov/documentLibrary/media/Advisory_Circular/draft_150_5300_17c.pdf

  • mayutilize.Also,thedraftreleaseisintendedtoprovidethecontractorssubmittingtheobstructiondatawiththestandardsandrecommendedpracticesforusingremotesensingtechnologiesinthecollectionofairportdata.

    ThereplacementACgoesontodiscusssomeofthemajorchangestosectionscoveringtheusesandlimita-tionsoftechnologiesotherthanaerialimagery(includingsatelliteimagery).

    Advisorygroups,suchastheTransportationResearchBoard(TRB),AV070AirportsGISSubcommittee(DA0301)haveplayedasignificantroleinadvancingtheacceptanceofLIDAR

    asaremotesensingtoolforairportobstructionmappingandidentifica-tion.TheirworkwaswrappedupthissummerandfeedbacksubmittedtotheFAAforreview.

    Furthermore,GPSnavigationtechnologyhasenabledtighterandmorenumerousapproachproceduresatairports(GPSApproachMinima).Thismeansloweringtheclearanceminimaandatthesametimebroaden-ingtheareawhereapproachesandmaneuveringmaytakeplace.Therefore,agreaterareasurroundingtheairfieldmustbenowcheckedforobstructions.Also,astheFAAmovedfromtheolder405aeronauticalstandards(FAA405,

    Figure 3 Effect of forward tilting the laser scanner, courtesy of Dr. Chris Parrish, NOAA-NGS. 2003.

    rescindedin2006)tothenewerareanavigationapproach(ANA)standards(describedinAC150/5300-17BandAC150/5300-18B),agreaterareasurround-ingtheairfieldthanbeforemustnowbeconsideredforobstructionanalysisunderthenewerstandards.Thesefac-torsdirectlyleadtoagreateramountofsurveywork,likelymademoreefficientthroughtheuseofairborneLIDAR.

    Role of NOAA-NGSTraditionallyithasbeentheresponsibil-ityofNOAANGSAeronauticalSurveyProgram(ASP)tofindandsurveytheseobstaclesandthentoprovidetheFAAwithgeo-informationregardingthelocationanddimensionsoftheobjects.Withsomanyairportstosurvey,NOAAhasassistedtheFAAinusingcontractorstoconductmanyofthesesurveys.Relyingontheirextensivecapabilitiesinprecisepositioningandremotesensing,NOAAhasdevelopedandprovidedguidelinesforconductingeverythingfromground-basedobstruc-tionmappingtoairbornedatacollectionwithaerialphotographyand(morerecently)airborneLIDARmapping.Arecentrevisiontothestatement-of-work(SOW)forcollectingdataforairportobstructionsnowincludesextensiveguidelinesontheuseofairborneLIDAR.(http://www.ngs.noaa.gov/RSD/AirportSOW.pdf).TheNGSteamcon-tinuestoprovidesupporttoFAAintheformofrecommendationsoncollectionspecificationsandproceduresaswellassupplyingaccuracyassessmentandQCofthedatasuppliedtoFAAbycontrac-tors.Thisnecessitatestheretentionof

    Displayed with permission LiDAR Magazine Vol. 2 No. 1 Copyright 2012 Spatial Media www.lidarnews.com

    https://www.faasafety.gov/files/gslac/library/documents/2006/Oct/9082/GPS%20Approach%20Minima%20JulAug06.pdfhttp://www.ngs.noaa.gov/RSD/AirportSOW.pdfhttp://www.ngs.noaa.gov/RSD/AirportSOW.pdf

  • in-houseairborneLIDARtechnologyexpertise,whichNOAApossessesandcontinuestoupgradeconstantly.NOAAalsoprovidescuttingedgeresearchtoFAA(forairborneLIDARsurvey)byexperimentingwithnewtechnology,softwareanddatacollectiontechniques.

    Researching Critical Aspects of Obstruction Mapping with LIDARPastandcurrentresearchelementsrelatingtoutilizingLIDARforverticalobstructionsinclude:

    1. Density(spot)analysis2. Sensorconfigurationandorienta-

    tiontests3. LIDARwaveformdeconvolution4. Radiometricintensityevaluation

    Dr.ChrisParrishofNOAA-NGShasbeenresearchingtheeffectivenessofairborneLIDARforOISdetectionandidentification.In2001attheUniversityofFlorida,heconductedsomeofthefirsttestsevaluatingtheimpactofspotspacingandspotdiameterondetectionrates,aswellassensororientation.Theseexperimentsledtointerestingconclusionsontherelationshipbetweenverticalandhorizontalpointdensityandsuccessratesofobjectdetection.Aboutthesametime,Dr.WaheedUddinattheUniversityofMississippibeganinvestigatingtheutilityofLIDARforairspacemanagement(AirportObstructionSpaceManagement).Additionally,Dr.UddinrecentlycompletedaresearchprojectfortheTRB(ACRP03-01LIDARDeploymentforAirportObstructionSurveys,NationalAcademyofSciences(NAS))thatfocusedonthedevelopmentofacost-effectivemethodologythatairports

    andtheirconsultantscanadopttoprocure,process,anduseLIDARdatainfurtheranceofcostreductionsandaccuracyenhancements.

    Byitsnature,anairborneLIDARsystemgeo-referencesthepointdata,soascertainingthegeo-locationoftheobjectswasrelativelystraightforward.Whatwaslessevidentintheinitialphaseoftheresearchwastheconfidenceindetectingtheuppermostextentofverticallyorientedobjects(suchasantennas).ThisisimportantinformationbecauseitistheelevationatwhichtheobstructionrisesabovetheO