DAVALATH-THESIS

70 Pages·2011·1.29 MB·English

A RIGGING CONVENTION FOR ISOSURFACE-BASED CHARACTERS
AThesis
by
MEGHANATARAJDAVALATH
Submittedto theOfficeofGraduateStudiesof
TexasA&MUniversity
inpartial fulfillmentoftherequirementsforthedegreeof
MASTEROFSCIENCE
May2011
MajorSubject: Visualization
A RIGGING CONVENTION FOR ISOSURFACE-BASED CHARACTERS
AThesis
by
MEGHANATARAJDAVALATH
Submittedto theOfficeofGraduateStudiesof
TexasA&MUniversity
inpartial fulfillmentoftherequirementsforthedegreeof
MASTEROFSCIENCE
Approvedby:
ChairofCommittee, TimMcLaughlin
CommitteeMembers, Ergun Akleman
JohnKeyser
Terran Boylan
Head ofDepartment, TimMcLaughlin
May2011
MajorSubject: Visualization
iii
ABSTRACT
A RiggingConventionforIsosurface-Based Characters. (May 2011)
MeghaNataraj Davalath,B.S., TheUniversityofTexasat Austin
Chair ofAdvisoryCommittee: TimMcLaughlin
This thesis presents a prototype system for generating animation control systems for
isosurface-based characters that blurs the distinction between a skeletal rig and a particle
system. Managing articulation and deformation set-up can be challenging for amorphous
characters whose surface shape is defined at render time and can only be viewed as an
approximation during the process of defining an animation performance. This prototype
systemutilizesconventionalscriptedtechniquesfordefininganimationcontrolsystemsin-
tegratedwithagraphicaluserinterfacethatprovidesartdirectablecontroloversurfacecon-
tour,shapeandsilhouetteforisosurface-basedcharacters. Onceanimated,thesecharacters
can berendered usingRendermansRIBlobbyimplementationandprovidevisualfeedback
offluidmotiontests. Theprototypesystemfitsnaturallywithincommonpracticesindigital
character setupand providestheanimatorcontroloverisosurface-based characters.
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To MyFamily
v
ACKNOWLEDGMENTS
First, I would like to thank Tim McLaughlin, who has been an excellent thesis chair,
providingmewithconstantencouragementthroughoutthecourseofthisthesis. Iamgrate-
ful to Terran Boylan, from DreamWorks Animation,for riggingthecharacter that inspired
thisthesisandbeinganexceptionalmentorsincethebeginning. Heguidedmethroughthe
entire process and answered any questions I had. Huge thanks to Marilyn Friedman and
DreamWorks Animation for the cooperation and ability to allow me to work with Terran
through this priceless opportunity. I would also like to thank the rest of my committee,
Ergun Akleman and John Keyser, for teaching me the key components in understanding
themeaningofimplicitsurfaces and renderingmethods.
I am hugely indebted to Jose Guinea Montalvo, a fellow vizzer and good friend, who
has helped me from the very beginning in everything from finding the focus of my thesis
toexplainingconcepts aboutRenderman particulartomy implementation.
SpecialthankstomyVizcompanions: AdanPena, forbeingmyrigging/thesisbuddy,
Nathan Bajandas, for being the most patient and wonderful animator working with my
deadlines, and lastly JuliePool, for being the creativitybehind the character that was used
as an examplefor this system. Other vizzers includeDavid Drell, Bob Graf, Leticia Silva,
TonyPiedra, Seth Schwartz and the rest of theVizLab forprovidingmewith an enjoyable
memoryofmytimeat TexasA&MUniversity.
Mostimportantly,Iwouldliketothankmyparents,NatarajandShylajaDavalath,and
my sister, Ranjani Davalath, for the constant loveand support they have givenme through
theupsand downsoflifeand neverlettingmelosesightofmydreams.
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TABLE OFCONTENTS
CHAPTER Page
I INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II PRIOR WORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
A. Character Design . . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Reference Material . . . . . . . . . . . . . . . . . . . . . 4
2. Character Form . . . . . . . . . . . . . . . . . . . . . . . 6
3. Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
B. Motionand ControlSystem . . . . . . . . . . . . . . . . . . . 10
C. TypesofSurfaces . . . . . . . . . . . . . . . . . . . . . . . . . 11
1. ImplicitSurfaces . . . . . . . . . . . . . . . . . . . . . . 12
a. DefinitionofImplicitSurfaces . . . . . . . . . . . . . 12
b. A Brief History of Implicit Surfaces in Com-
puterGraphics . . . . . . . . . . . . . . . . . . . . . 13
c. PolygonizationofImplicitSurfaces . . . . . . . . . . 18
D. CaseStudies . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Case Study: TheAbyss(1989) . . . . . . . . . . . . . . . 19
2. Case Study: Flubber(1997) . . . . . . . . . . . . . . . . . 22
3. Case Study: Monstersvs. Aliens(2009) . . . . . . . . . . 23
III METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . 25
A. Animationand Performance Requirements . . . . . . . . . . . 25
B. ToolsandProcesses . . . . . . . . . . . . . . . . . . . . . . . 26
C. Isosurfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
D. Isosurface-Based Characters . . . . . . . . . . . . . . . . . . . 28
1. Converting an ExistingCharacter into an Isosurface-
based Character . . . . . . . . . . . . . . . . . . . . . . . 28
2. Creating an Isosurface-based Character . . . . . . . . . . . 29
a. DissectingaCharacter . . . . . . . . . . . . . . . . . 29
b. Character Form . . . . . . . . . . . . . . . . . . . . 31
c. Motion . . . . . . . . . . . . . . . . . . . . . . . . . 31
IV IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . 35
A. Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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CHAPTER Page
B. Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
C. Isosurfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1. IsosurfacePrimitives . . . . . . . . . . . . . . . . . . . . 36
2. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3. RIB Format . . . . . . . . . . . . . . . . . . . . . . . . . 38
4. BlobbyAttributes . . . . . . . . . . . . . . . . . . . . . . 39
D. Rendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1. ViewportRepresentation . . . . . . . . . . . . . . . . . . 40
2. Generating RIB File . . . . . . . . . . . . . . . . . . . . . 41
3. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . 42
E. Scripting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
1. Graphical UserInterface . . . . . . . . . . . . . . . . . . 42
2. ModularRiggingSystem . . . . . . . . . . . . . . . . . . 43
3. Languages . . . . . . . . . . . . . . . . . . . . . . . . . . 46
V CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
B. Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
C. Isosurface-Based Character Prototype . . . . . . . . . . . . . . 49
D. Bubbles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
VI FUTURE WORK . . . . . . . . . . . . . . . . . . . . . . . . . . 53
A. Facial Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 53
B. MotionBlur . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
C. Viewport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
D. Ray Tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
E. DensityFunction . . . . . . . . . . . . . . . . . . . . . . . . . 55
F. Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
VITA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
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LIST OFFIGURES
FIGURE Page
1 Left: Artwork and character poses from different angles drawn by
JuliePool. Right: A samplestoryboard drawnby JuliePool. . . . . . . . 5
2 Winged characterrig and model . . . . . . . . . . . . . . . . . . . . . . 7
3 Surface types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Blobby andRadius values . . . . . . . . . . . . . . . . . . . . . . . . . 14
5 Superquadricellipsoids . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Polygonalsurface ofhumanfist . . . . . . . . . . . . . . . . . . . . . . 17
7 Screenshots from TheAbyss . . . . . . . . . . . . . . . . . . . . . . . 20
8 Behind theScenes screenshotsfrom TheAbyss . . . . . . . . . . . . . . 21
9 Behind theScenes screenshotsfrom TheAbyss . . . . . . . . . . . . . . 21
10 Screenshots from Monstersvs. Aliens . . . . . . . . . . . . . . . . . . . 23
11 Isosurface Primitives, left to right: two spheres, two ellipsoids, nine
segmentchains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
12 Left to Right: Original Norman mesh, rigid body stand-in viewport
representation,final high-resolutionisosurfacerender . . . . . . . . . . . 28
13 Left: Reference material used to develop design of character, Right:
Artwork oftheorthogonalposeofcharacter by JuliePool . . . . . . . . . 30
14 Top: Character sheet provides insights into range-of-motion for the
character, Bottom: Character walkcycle. Drawnby JuliePool . . . . . . 32
15 Left toRight: ModularRiggingtab,Isosurfaces tab, Attributestab . . . . 43
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FIGURE Page
16 Top: Ellipsoidal primitives. Middle: Segment Blob Chain. Bottom:
AttachingisosurfacefunctionalitytotheNormanrig . . . . . . . . . . . 48
17 Screenshots oftransientlimbscominginand outofthebodyinorder
labeled 1-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
18 A few screenshots showing the different callisthenic motions for the
blobbycharacter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
19 Screenshots ofvariousphasesofthewalkcycle . . . . . . . . . . . . . . 51
20 Screenshots ofsystemworkingwithaparticlesystem . . . . . . . . . . . 52
1
CHAPTER I
INTRODUCTION
The movie Monstersvs. Aliens, by DreamWorks Animation in 2009, defined a need for a
hero blobby character that had personality. Visually, B.O.B. was perfect; the shading was
beautifully done despite being very difficult to generate UV coordinates on isosurfaces.
For being procedurally shaded, the colors and effects added to the surface worked well
in every shot. The bubbling effect on the inside also provided a nice touch of detail that
blended in with the overall look of the character and added personality. B.O.B. was the
main inspiration for this thesis topic . It required solving the problem of combining an
unconventional surface with rigging. This character was done for a single purpose for the
movie but after realizing there are many other instances such a convention could be used,
itwasdecidedthatasystemthatallowedanyriggertoproduceanamorphousrigwouldbe
beneficial.
Due to the development of more powerful and faster computer systems, the use of
animatedamorphousvolumetricshapeshasgraduallycomeintouseinmanysectorsofthe
visualization industry, including: cinema, entertainment, games and information analysis.
In movies, characters and effects have required amorphous volumes (smoke monsters, fire
entities, water snakes), but most of these were achieved with single-use solutions to be on
screen for only a short time. Currently there are no published methods within the frame-
work of standard production practices for defining motion control systems and providing
animationcontroloverisosurfaceshapes. Thegoal ofthisresearch isto providea conven-
tionfortheriggertodevelopanappropriatemotionandcontrolsystemfortheanimatoron
whichtoanimateanisosurface-basedcharacterportrayinggelatinousoramorphousmove-
ment. This is an area of computer graphics currently existing purely in the effects world;
thereforethere isaneed forcharacter drivenkinematics.