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dc.contributor.authorFederolf, Peter
dc.date.accessioned2013-11-08T11:49:06Z
dc.date.available2013-11-08T11:49:06Z
dc.date.issued2013-10-30
dc.identifierSeksjon for fysisk prestasjonsevne / Department of Physical Performances
dc.identifier.citationPLoS ONE. 2013, 8, e78689no_NO
dc.identifier.urihttp://hdl.handle.net/11250/171002
dc.description© 2013 Peter Andreas Federolf. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.no_NO
dc.description.abstractMarker-based human motion analysis is an important tool in clinical research and in many practical applications. Missing marker information caused by occlusions or a marker falling off is a common problem impairing data quality. The current paper proposes a conceptually new gap filling algorithm and presents results from a proof-of-principle analysis. The underlying idea of the proposed algorithm was that a multitude of internal and external constraints govern human motion and lead to a highly subject-specific movement pattern in which all motion variables are intercorrelated in a specific way. Two principal component analyses were used to determine how the coordinates of a marker with gaps correlated with the coordinates of the other, gap-free markers. Missing marker data could then be reconstructed through a series of coordinate transformations. The proposed algorithm was tested by reconstructing artificially created gaps in a 20-step walking trial and in an 18-s one-leg balance trial. The measurement accuracy’s dependence on the marker position, the length of the gap, and other parameters were evaluated. Even if only 2 steps of walking or 1.8 s of postural sway (10% of the whole marker data) were provided as input in the current study, the reconstructed marker trajectory differed on average no more than 11 mm from the originally measured trajectory. The reconstructed result improved further, on average, to distances below 5 mm if the marker trajectory was available more than 50% of the trial. The results of this proof-of-principle analysis supported the assumption that missing marker information can be reconstructed from the intercorrelations between marker coordinates, provided that sufficient data with complete marker information is available. Estimating missing information cannot be avoided entirely in many situations in human motion analysis. For some of these situations, the proposed reconstruction method may provide a better solution than what is currently available.no_NO
dc.language.isoengno_NO
dc.publisherPLOSno_NO
dc.subjectalgorithmsno_NO
dc.subjectsignal to noise rationo_NO
dc.subjectkneesno_NO
dc.subjectvector spacesno_NO
dc.subjectknee jointsno_NO
dc.subjectwalkingno_NO
dc.subjecthuman movementno_NO
dc.subjectinterpolationno_NO
dc.titleA novel approach to solve the “Missing marker problem” in marker-based motion analysis that exploits the segment coordination patterns in multi-limb motion datano_NO
dc.typeJournal articleno_NO
dc.typePeer reviewedno_NO
dc.subject.nsiVDP::Mathematics and natural science: 400::Basic biosciences: 470no_NO
dc.subject.nsiVDP::Agriculture and fishery disciplines: 900::Agriculture disciplines: 910no_NO
dc.source.journalPLoS ONEno_NO
dc.identifier.doi10.1371/journal.pone.0078689


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