A Procedure for Automatically Estimating Model Parameters in Optical Motion Capture

Model-basedoptical motion capturesystemsrequireknowledgeof the position of the markersrelative to the underlyingskeleton,the lengthsof the skeleton’ s limbs, and which limb eachmarker is attachedto. Thesemodelparametersaretypically assumed andenteredinto thesystemmanually, althoughtechniquesexist for calculatingsomeof them,suchasthepositionof themarkersrelative to theskeleton’ s joints. We presenta fully automaticprocedurefor determiningthesemodelparameters.It tracksthe2Dpositionsof themarkersonthecameras’ imageplanesanddetermineswhich markerslie on eachlimb beforecalculatingthepositionof theunderlyingskeleton.The only assumptionis thattheskeletonconsistsof rigid limbsconnectedwith ball joints. Theproposedsystemis demonstratedonanumberof realdataexamplesandis shown to calculategoodestimatesof themodelparametersin each.