Abstract. This paper proposes a new user interface paradigm for motion capture based animation systems, providing intuitive and efficient ways to visualize the main motion capture concepts and operations. A prototype system was built, implementing the prop

2.1BasicInternalStructures

Thefundamentalstructureusedinthesystemiscomposedbytwoentities:anactorandmotions.

Theactoristreatedasaskeleton.Itstopologyisrepresentedbyagraphformedbyjointsandlinks.Itsgeometryisrepresentedbyasetofconnectedlimbs(Figure1).Thisdescriptionisadequatetobeusedinamotioncaptureani-mationsystem,sinceitre ectsthestructureofanarticulated gure.Fordataacquisition,markersareattachedatthejointsofaliveperformer(thereal

actor).Figure1:Topologicalandgeometricaldescriptionofanactorusedinthesystem.Attheprogramminglevel,theactorisrepresentedusingamodi edversionofZeltzer’sAPJ(AxisPositionJoint)structure[3],adaptedtoworkwithmotioncaptureddata.

Motionsarebestrepresentedascurvesintime(Figure

2).

Figure2:Examplesofjointmotioncurves.