Procedural Skeletons:Kinematic Extensions to CGA-Shape

Grammars

Martin Ilčík, Stephan FiedlerWerner Purgathofer, Michael Wimmer

Institute of Computer Graphics and Algorithms

Vienna University of Technology

Preview

Procedural modelingGrammarsArticulated objects

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Procedural modeling

↑ Abstraction↓ Design costs↓ Artistic skills↑ Reusability

↑ Domain knowledge↓ Local control↑ Formal theory↓ Reconstruction

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CityEngine, Pascal Müller

Nature vs. Urbanism

ElementsSurvivalJaggedLong evolution

RegularShort termPlanarityBatch changes

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Rome Rebuild, Pascal Müller

Split grammars

Sets of shapes instead of symbolsLarge amount of rules and attributesAttribute propagationRule selectionImage based reconstruction

SymmetriesVisual editing

[Wonka et al. 2003]

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CGA grammars

Scope to oriented bounding boxestransformation rulessplits and repetitionabsolute and relative scalingcomponent splits

SequentialOcclusionSnapping[Müller et al. 2006][Lipp et al. 2008]

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Procedural modeling of cities

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CityEngine, Pascal Müller

Poses and Expressions

PoseExpressionSemanticsRelationsFunctionality

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Poses and Expressions

PoseExpressionSemanticsRelationsFunctionality

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Poses and Expressions

PoseExpressionSemanticsRelationsFunctionality

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Poses and Expressions

PoseExpressionSemanticsRelationsFunctionality

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Poses and Expressions

PoseExpressionSemanticsRelationsFunctionality

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Excavator Example - Basis

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Excavator Example - Basis

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Excavator Example - Basis

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Excavator Example - Basis

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Excavator Example - Motor

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Excavator Example - Cabin

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Excavator Example - Cabin

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Excavator Example - Chassis

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Excavator Example - Wheels

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Excavator Example - Arm

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Excavator Example - Arm

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Excavator Example - Arm

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Excavator Example - Shovel

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Excavators

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Excavators

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Excavators

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Excavators

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Excavators

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Excavators

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Pose description

Kinematic ShapesRigid bodiesBones

Parent linkChildren links

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Pose description

Kinematic ShapesRigid bodiesBones

Parent linkChildren links

Joint

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Pose description

Kinematic ShapesRigid bodiesBones

Parent linkChildren links

JointDefault pose

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Pose description

Kinematic ShapesRigid bodiesBones

Parent linkChildren links

JointDefault poseLimited transformations

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Pose description

Kinematic ShapesRigid bodiesBones

Parent linkChildren links

JointDefault poseLimited transformationsCurrent transformation

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Pose description

Kinematic ShapesRigid bodiesBones – Automatic

Parent linkChildren links

JointDefault poseLimited transformationsCurrent transformation

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Pose description

Kinematic ShapesRigid bodiesBones – Automatic

Parent linkChildren links

Joint – Kinematic RulesDefault poseLimited transformationsCurrent transformation

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Starting configuration

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Sequential split

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Parallel split

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Component split

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Properties

Kinematic independence

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Grammar ExampleBuildingRoot →

Subdiv(“Y”, 3.5){Basement|Floor}

Floors → Repeat(“Y”, 3a){Floor}

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Grammar ExampleBuildingRoot →

Subdiv(“Y”, 3.5){Basement|Floor}

Floors → Repeat(“Y”, 3a){Floor}

Floor → Comp(“sidefaces”){FloorFacade}

FloorFacade → Repeat(“Y”, 1.5a){WindowPane}

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Grammar ExampleBuildingRoot →

Subdiv(“Y”, 3.5){Basement|Floor}

Floors → Repeat(“Y”, 3a){Floor}

Floor → KinematicRotation(RotLimits,CurrentRot)Comp(“sidefaces”){FloorFacade}

FloorFacade → Repeat(“Y”, 1.5a){WindowPane}

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Grammar Example

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Conclusions

Poses enrich semanticsRule based

Simple extension to CGAIntegrationInteractivity

Rigging for freePost-processing

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Future Work

Connectivity preservationMass and stabilityDeformationsAnimationIK

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Acknowledgements

Johannes Kühetreiber, Frederico DusbergerDaniel Scherzer, Markus LippReviewers

FIT-IT Visual Computing InitiativeGameWorld Project

THANK YOU FOR YOUR ATTENTION

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