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

3DEulerangleextraction2,pre- lteringandhierarchicalanglegenerationareprovidedinthismodule.

ProcessingModule

Theprocessingmodulecomprisesthesetoftoolsformotionanalysis,manip-ulationandreuse.Threebasicmotionoperationtypesarede ned: ltering;concatenation;andblending.Theirobjectiveistoprovidee cientwaystomodifytheoriginalcaptureddata.Withthesetools,theuserisabletogeneratenewclassesofmotions,inheritingthealivenessandcomplexitytypicalofnaturalmotion.

Filteringoperationscanbeappliedtothejointcurvesofamotion,toreducenoiseorevenmodifyspeci ccomponentsofthemovement.In[9],Williamsusedamultiresolution lteringapproachtodecomposethemotioninfrequencybands,thusallowingmodi cationsinahigherlevelofabstraction.

Withconcatenationoperations,longeranimationscanbeproducedbycombiningseveralmotionsinsequence.Smoothtransitionsbetweenthecombinedmotionscanbeproducedusingalgorithmsbasedonblendingofmotionparameters[4].Spacetimeconstraints[12]canalsobeusedtogenerateseamlessanddynamicallyplausibletransitions,withexcellentresults.

Blendingoperationsarenormallyusedtocombinespecialcharacteristicsofdif-ferentmotions.Inthiscase,theexistenceoftoolsformotionsynchronizationandreparametrizationisveryimportanttohelpintheblendingprocess,ensuringacoherentresult.

OutputModule

Themainobjectiveofthismoduleistoprovidewaystostorethecompositioncreatedbytheuser,thusmaintainingandexpandingtheexistingmotionlibrary.Auniversaldataformatwasde ned,embodyingthemaincharacteristicsofmostmotiondataformatsavailablenowadays.Consequently,thesystemcanbeusedasarobustconversortomotioncapturedataformats.

UserInterface

Theuserinterfaceusedinthesystemisbasedonavisualrepresentationofmotioncapturebasicconcepts,suchasmotionsandoperations.

Webelievethatitisalsointerestingtosupplyanon-graphicalusercommunica-tion,usingaexpressionlanguagethatrepresentsalltheactionsthatwouldbedoneusingthegraphicaldescriptionprovidedintheuserinterface.

2Inthecaseofdatawithpositionalinformationonly.