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108Chapter6viewbecausethedisplayishead-mounted31TheHoloLenshasanuntetheredandwirelessdesigndisplayshologramswithaframerateof60Hzandweighs580g32 TheHolographicRemotingPlayerapplicationinUnitywasusedtostreamvirtualobjectstotheHoloLensThepositionandorientationofhologramswereexpressedinadifferentreferencesystemtheHoloLensreferenceframeLinkingtheHoloLenstothetrackingsystem TheIGSsystemandtheHoloLensbothusedtheirownreferenceframeInordertovisualizeaplannedpositionofatracked object as ahologram theplanningneeded tobe expressedin thereferenceframeoftheHoloLensAtransformationbetweentheIGSreferenceframeandtheHoloLensreference frame(HoloLensT IGS) wasnecessary ThepositionandorientationoftheHoloLensneededtobetrackedbytheIGSsystem(intheIGSreferenceframe)Amountwithreflectivemarkerswas3Dprintedandattachedwithauniquefittothesideof theHoloLens(Figure1) Thepositionandorientationof thismount weretrackedbytheIGSsystem(MountTIGS)SincethetrackerwasattachedtothesideoftheHoloLensasecondtransformationwasrequiredtocorrecttheoffsetbetweenpositionofthemountandtheHoloLensreferenceframe(
HoloLensTMount)ThisstatictransformationwasdeterminedduringacalibrationprocessThecompletetransformation(HoloLensTIGS)wascalculatedusingthefollowingformulaHoloLensTIGS=HoloLensTMountMountTIGSThistransformationmadeitpossibletovisualizeobjectsfromthevirtualplanningashologramsin3DspaceontheHoloLensACCURACYSTUDYTwoexperimentsweredesignedtoevaluatetheaccuracyoftheARIGSsystematight-fitexperimenttoevaluatethenavigationerrorandaloose-fitexperimenttoevaluatethetotalerroroftheARIGSsystem(navigationerror+usererror+ARvisualizationerror)TheARvisualizationerrorcouldnotbemeasureddirectlysinceitwasimpossibletoperformphysicalmeasurementsonvirtualhologramsThiserrorwasdeductedfromtheresultsoftheexperiments TheexperimentsaredescribedindetailbelowTight-FitExperimentThenavigationerrorisahardwareerror,whichoriginatesfrommeasuringthepositionofthereflectivemarkersandthecalculationof