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

Thedefaulteasy-in/easy-outblendingparameterscanbemodi edbydouble-clickinginthedesiredblendingintervaloftheConcatenation

Window.

Figure14:Blendingintervals(detailfromConcatenationWindow).

Blending

Blendingisthelasttypeofmotionoperationde nedintheprimarysetoftheprototypesystem.

AsintheConcatenationWindow,allmotionsselectedbytheuserareplacedinacanvas,providingaglobalviewoftheoperation.Forblending,however,newobjectswereintroducedtoassistinthespeci cation.

Thesenewobjectsarethetime-markers,andtheirpurposeistosynchronizekeypointsinthecombinedmotions.Forexample,whencombiningtwodi erenttypesofwalkmovements,itisdesirablethatthefeetreachthegroundatthesameinstantinbothmotions,otherwisestrangeresultscanbeproduced.

Figure15showsasnapshotofablendingoperationbetweenthreedi erentmotions.Thetime-markers(detailfromFigure15)wereusedtoestablishacorrespondencebetweenthekeystepsinthecombinedmotions.

Thissynchronizationprocesswillreparametrizethemotionsaccordingtothepositionofthetime-markers,matchingtheiroccurrenceintime.Todothat,algorithmsbasedontimewarpingareused.Agoodexamplecanbefoundin[9].

3.4Higher-LevelInterfaceObjects

Tocompletetheinterfacedescription,wepresentotherobjectsthatareimpor-tanttocreateapowerfulanimationenvironment.