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计算机与信息学院本科毕业设计（论文）-11-外文资料翻译—原文部分FundamentalsofHumanAnimation(FromPeterRatner.3DHumanModelingandAnimation[M].America:Wiley,2003:243~249)Ifyouarereadingthispart,thenyouhavemostlikelyfinishedbuildingyourhumancharacter,createdtexturesforit,setupitsskeleton,mademorphtargetsforfacialexpressions,andarrangedlightsaroundthemodel.Youhavethenarrivedatperhapsthemostexcitingpartof3-Ddesign,whichisanimatingacharacter.Uptonowtheworkhasbeensomewhatcreative,sometimestedious,andoftendifficult.Itisverygratifyingwhenallyourpreviouseffortsstarttopayoffasyouenlivenyourcharacter.Whenanimating,thereisacreativeflowthatincreasesgraduallyovertime.Youarenowatthephasewhereyoubecomeboththeactorandthedirectorofamovieorplay.Althoughanimationappearstobeamorespontaneousact,itisneverthelessjustaschallenging,ifnotmoreso,thanallthepreviousstepsthatleduptoit.Youranimationswilllookpitifulifyoudonotunderstandsomebasicfundamentalsandprinciples.Thefollowingpointersaremeanttogiveyousomedirection.Feelfreetoexperimentwiththem.Bendandbreaktheruleswheneveryouthinkitwillimprovetheanimation.SOMEANIMATIONPOINTERS1.Tryisolatingparts.Sometimesthisisreferredtoasanimatinginstages.Ratherthantryingtomoveeverypartofabodyatthesametime,concentrateonspecificareas.Onlyonesectionofthebodyismovedforthedurationoftheanimation.Thenreturningtothebeginningofthetimeline,anothersectionisanimated.Bysuccessivelyreturningtothebeginningandanimatingadifferentparteachtime,theentireprocessislessconfusing.2.Putinsomelagtime.Differentpartsofthebodyshouldnotstartandstopatthesametime.Whenanarmswings,thelowerarmshouldfollowafewframesafterthat.Thehandswingsafterthelowerarm.Itislikeachainreactionthatworksitswaythroughtheentirelengthofthelimb.3.Nothingevercomestoatotalstop.Inlife,onlymachinesappeartocometoadeadstop.Muscles,tendons,force,andgravityallaffectthemovementofahuman.Youcanprovethistoyourself.Trypunchingtheairwithafullextension.Noticethatyourfisthasabounceattheend.Ifapartcomestoastopsuchasamotionhold,keyframeitonceandthenagainafterthreetoeightormorekeyframes.Yourmotiongraphwillthenhaveacurvebetweenthetwoidenticalkeyframes.Thiswillmakethepartappeartobounceratherthancometoadeadstop.4.Addfacialexpressionsandfingermovements.Yourdigitalhumanshouldexhibitsignsoflifebyblinkingandbreathing.Ablinkwillnormallyoccurevery60seconds.Atypicalblinkmightbeasfollows:Frame60:Botheyesareopen.Frame61:Therighteyecloseshalfway.Frame62:Therighteyeclosesallthewayandthelefteyecloseshalfway.Frame63:Therighteyeopenshalfwayandthelefteyeclosesalltheway.Frame64:Therighteyeopensallthewayandlefteyeopenshalfway.Frame65:Thelefteyeopensalltheway.计算机与信息学院本科毕业设计（论文）-12-Closingtheeyesatslightlydifferenttimesmakestheblinklessmechanical.Changingfacialexpressionscouldbejustusingeyemovementstoindicatethoughtsrunningthroughyourmodel'shead.Thehandswillappearstiffifyoudonotaddfingermovements.Toomanystudentsaretoolazytotakethetimetoaddfacialandhandmovements.Ifyoumaketheextraeffortforthesedetailsyouwillfindthatyouranimationsbecomemuchmoreinteresting.5.Whatisnotseenbythecameraisunimportant.Ifanarmgoesthroughalegbutisnotseeninthecameraview,thendonotbothertofixit.Ifyouwantahandtoappearclosetothebodyandthecameraviewmakesitseemtobecloseeventhoughitisnot,thenwhymoveitanycloser?Thisalsoappliestosets.Thereisnoneedtobuildanentirehouseifalltheactiontakesplaceinthelivingroom.Considerpaintingbackdropsratherthanmodelingeverypartofascene.6.Useaminimumamountofkeyframes.Toomanykeyframescanmakethecharacterappeartomoveinspasticmotions.Sharp,cartoonlikemovementsarecreatedwithcloselyspacedkeyframes.Floatyorsoft,languidmotionsaretheresultofwidelyspacedkeyframes.Ananimationwilloftenbeamixtureofboth.Trytolookforwaysthatwillabbreviatethemotions.Youcanretaintheessentialelementsofananimationwhilereducingtheamountofkeyframesnecessarytocreateagesture.7.Anchorapartofthebody.Unlessyourcharacterisintheair,itshouldhavesomepartofitselflockedtotheground.Thiscouldbeafoot,ahand,orboth.Whicheverportionisonthegroundshouldbeheldinthesamespotforanumberofframes.Thispreventsunwantedslidingmotions.Whenthemodelshiftsitsweight,thefootthattouchesdownbecomeslockedinplace.Thisisespeciallytruewithwalkingmotions.Thereareanumberofwaystolockpartsofamodeltotheground.Onemethodistouseinversekinematics.Thegoalobject,whichcouldbeanull,automaticallylocksafootorhandtothebottomsurface.Anothermethodistomanuallykeyframethepartthatneedstobemotionlessinthesamespot.Thecharacteroritslimbswillhavetobemovedandrotated,sothatfootorhandstaysinthesameplace.Ifyouareusingforwardkinematics,thenthiscouldmeankeyframingpracticallyeveryframeuntilitistimetounlockthatfootorhand.8.Acharactershouldexhibitweight.Oneofthemostchallengingtasksin3-Danimationistohaveadigitalactorappeartohaveweightandmass.Youcanuseseveraltechniquestoachievethis.Squashandstretch,orweightandrecoil,oneofthe12principlesofanimationdiscussedinChapter12,isanexcellentwaytogiveyourcharacterweight.Byaddingalittlebouncetoyourhuman,heorshewillappeartorespondtotheforceofgravity.Forexample,ifyourcharacterjumpsupandlands,liftthebodyupalittleafterit