Procedural Skeletons: Kinematic Extensions to CGA-Shape Grammars Martin Ilčík, Stephan Fiedler Werner Purgathofer, Michael Wimmer Institute of Computer Graphics and Algorithms Vienna University of Technology

Preview Procedural modeling Grammars Articulated objects Martin Ilčík 2

Procedural modeling ↑ Abstraction ↓ Design costs ↓ Artistic skills ↑ Reusability ↑ Domain knowledge ↓ Local control ↑ Formal theory ↓ Reconstruction Martin Ilčík 3 CityEngine, Pascal Müller

Nature vs. Urbanism Elements Survival Jagged Long evolution Regular Short term Planarity Batch changes Martin Ilčík 4 Rome Rebuild, Pascal Müller

Split grammars Sets of shapes instead of symbols Large amount of rules and attributes Attribute propagation Rule selection Image based reconstruction Symmetries Visual editing [Wonka et al. 2003] Martin Ilčík 5 image by Peter Wonka

CGA grammars Scope to oriented bounding boxes transformation rules splits and repetition absolute and relative scaling component splits Sequential Occlusion Snapping [Müller et al. 2006] [Lipp et al. 2008] Martin Ilčík 6 image by Markus Lipp

Procedural modeling of cities Martin Ilčík 7 CityEngine, Pascal Müller

Poses and Expressions Pose Expression Semantics Relations Functionality Martin Ilčík 8

Poses and Expressions Pose Expression Semantics Relations Functionality Martin Ilčík 9

Poses and Expressions Pose Expression Semantics Relations Functionality Martin Ilčík 10

Poses and Expressions Pose Expression Semantics Relations Functionality Martin Ilčík 11

Poses and Expressions Pose Expression Semantics Relations Functionality Martin Ilčík 12

Excavator Example - Basis Martin Ilčík 13

Excavator Example - Basis Martin Ilčík 14

Excavator Example - Basis Martin Ilčík 15

Excavator Example - Basis Martin Ilčík 16

Excavator Example - Motor Martin Ilčík 17

Excavator Example - Cabin Martin Ilčík 18

Excavator Example - Cabin Martin Ilčík 19

Excavator Example - Chassis Martin Ilčík 20

Excavator Example - Wheels Martin Ilčík 21

Excavator Example - Arm Martin Ilčík 22

Excavator Example - Arm Martin Ilčík 23

Excavator Example - Arm Martin Ilčík 24

Excavator Example - Shovel Martin Ilčík 25

Excavators Martin Ilčík 26

Excavators Martin Ilčík 27

Excavators Martin Ilčík 28

Excavators Martin Ilčík 29

Excavators Martin Ilčík 30

Excavators Martin Ilčík 31

Pose description Kinematic Shapes Rigid bodies Bones Parent link Children links Martin Ilčík 32

Pose description Kinematic Shapes Rigid bodies Bones Parent link Children links Joint Martin Ilčík 33

Pose description Kinematic Shapes Rigid bodies Bones Parent link Children links Joint Default pose Martin Ilčík 34

Pose description Kinematic Shapes Rigid bodies Bones Parent link Children links Joint Default pose Limited transformations Martin Ilčík 35

Pose description Kinematic Shapes Rigid bodies Bones Parent link Children links Joint Default pose Limited transformations Current transformation Martin Ilčík 36

Pose description Kinematic Shapes Rigid bodies Bones – Automatic Parent link Children links Joint Default pose Limited transformations Current transformation Martin Ilčík 37

Pose description Kinematic Shapes Rigid bodies Bones – Automatic Parent link Children links Joint – Kinematic Rules Default pose Limited transformations Current transformation Martin Ilčík 38

Starting configuration Martin Ilčík 39

Sequential split Martin Ilčík 40

Parallel split Martin Ilčík 41

Component split Martin Ilčík 42

Properties Kinematic independence Martin Ilčík 43

Grammar Example BuildingRoot → Subdiv(“Y”, 3.5){Basement|Floor} Floors → Repeat(“Y”, 3a){Floor} Martin Ilčík 44

Grammar Example BuildingRoot → Subdiv(“Y”, 3.5){Basement|Floor} Floors → Repeat(“Y”, 3a){Floor} Floor → Comp(“sidefaces”){FloorFacade} FloorFacade → Repeat(“Y”, 1.5a){WindowPane} Martin Ilčík 45

Grammar Example BuildingRoot → Subdiv(“Y”, 3.5){Basement|Floor} Floors → Repeat(“Y”, 3a){Floor} Floor → KinematicRotation(RotLimits,CurrentRot) Comp(“sidefaces”){FloorFacade} FloorFacade → Repeat(“Y”, 1.5a){WindowPane} Martin Ilčík 46

Grammar Example Martin Ilčík 47

Conclusions Poses enrich semantics Rule based Simple extension to CGA Integration Interactivity Rigging for free Post-processing Martin Ilčík 48

Future Work Connectivity preservation Mass and stability Deformations Animation IK Martin Ilčík 49

Acknowledgements Johannes Kühetreiber, Frederico Dusberger Daniel Scherzer, Markus Lipp Reviewers FIT-IT Visual Computing Initiative GameWorld Project THANK YOU FOR YOUR ATTENTION Martin Ilčík 50