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Title: Layered Avatar Behavior Model and Script Language for the Object Interaction


1
Layered Avatar Behavior Model and Script Language
for the Object Interaction
  • Jae-Kyung Kim
  • 2007-08-10
  • ki187cm_at_gmail.com

2
Contents
  • Part I Ph.D Degree Dissertation
  • Introduction
  • Related Works
  • Research Goals
  • Layered Avatar Behavior Model and Script Language
  • Avatar-Object Interaction Model
  • Layered Script Language Approach
  • Empirical Evaluations
  • Conclusion
  • Part II Current Research Interests
  • Avatar Augmented Annotation Interface for
    e-Learning

3
Introduction
  • Recent studies on human character(Avatar)
    animation are mostly focused on realistic motion
    representation
  • ex) Facial Animation, synchronization between
    lips movement and speech text, hair animation, so
    on.
  • Creating human character motion by motion capture
    technique
  • Very useful for creating human motion, and
    low-level animation
  • Many researches about avatar motion control
    mainly care about realistic motion
  • Our main goal is to provide simple user interface
    by controlling avatar motion at high-level
    concept

4
Related Works(1/2)
  • Low-level Animation
  • Classic and basic control technique
  • Rotate move every parts of avatar body
  • Depending on animators skill, any desired motion
    can be created in detail manner
  • However, it is very hard work for unskilled user
    to control and create avatar motion
  • 3DS Max, Maya, Motion capture

5
Related Works(2/2)
  • Avatar Script Languages
  • Represents avatar body and facial motion in
    language format (eg. XML)
  • Control synchronization and intensity of
    behaviors through parameters
  • Most scripts use pre-defined general behaviors
  • Difficulty in creating script due to complicated
    parameters and synchronization
  • Some scripts stick to specific format for an
    engine, possibly causing low compatibility
  • AML, CML, XSTEP, TVML, etc.

6
Research Goals Motivation
  • Create animation scenario script with less effort
    and time in a specific application domain
  • Pre-defined general behavior cant support all
    application domains
  • More abstract representation is required for
    authoring script
  • Explicitly separate user interface and animation
    engine for extensibility and compatibility
  • Existing scripts support user interface and
    animation engine level at the same time
  • Standard format and structure is needed

7
Layered Avatar Behavior Model and Script
User
  • Overall structure

Context Menu Interface (Display)
Domain Interface Layer
Avatar-Object Interaction Model
Recording
1st Translator (Task-to-High)
Task-Level Behavior Script
Translating
Motion Sequence Layer
High-level Motion Script
Translating
Application Layer
2nd Translator (High-to-Primitive)
Primitive Motion Script
Primitive Motion Script
Geometric Information
Avatar Low-level Animation Data
Object Low-level Animation Data
Avatar Low-level Animation Data
Object Low-level Animation Data
Application
Application
8
Avatar-Object Interaction Model(1/2)
  • Basic Object Structure
  • Proposed model has multiple objects below the
    ObjectList element
  • An object is composed of three elements
  • Context object state, access privilege,
    controlpoint and domain type
  • ExecutableBehaviors all executable behaviors
    for user interface menu
  • MotionList motion sequence to complete a
    behavior

ObjectList
Object
Executable Behaviors
Context
MotionList
Basic XML DTD sturcture
9
Avatar-Object Interaction Model(2/2)
Avatar-Object Interaction Model
Selectable Behaviors
Context
User
Behaviors Selection
State
ControlPoint
Select a Behavior
AcessGroup
Domain
Task Planning
Behaviors List
Executable Behaviors
Generating Motions
MotionList

Motion List
10
Context Element(1/5)
  • State Element
  • Describes internal object states by pair of
    variable and value attributes
  • Variable has affective motion and current state
    methods
  • Affective motion defines post-state value, and
    corresponding motion which changes the state
  • Current state function is defined in XSLT script
    that processes state element to make boolean
    result output of current state value
  • Behavior menu and motion sequence are decided
    according to changes of state variables value

11
Context Element(2/5)
Variable DoorState
  • IF
  • (1) Event Motion Affective Motion
  • (2) State Function TRUE
  • THEN
  • (1) Make up of Variable list which satisfy
    conditions
  • (2) Set each variable Value to Post_State
  • (3) Output boolean result by State Function

Affective Motion
Event Motion
Post State closed
Motion Name close
close
Value closed
Result State
State Functions IsClosed
True
V
V
V
Interaction
State Changes
V
V
Door Object
12
Context Element(3/5)
  • ControlPoint Element
  • Spatial reference points around a object where
    avatar stands and interact with it
  • Depending on the behaviors and object states, a
    object may have various points
  • A point is consisted of position, direction and
    contact elements
  • The elements has coarse references to represent
    spatial location at high-level
  • Human readable
  • Independent from physical geometric object models
  • Used for behavior sub-tasking and motion
    sequencing

13
Context Element(4/5)
  • Position
  • Relative 5 basic and 4 composed positions for
    each objects
  • Standard axis is z for front on zy-plane
  • Direction
  • Object relative 4 basic and composed directions
    to determine avatars orientation
  • Rotation axis is y and zero degree for forward
    direction
  • Contact
  • designate a specific part of the object when the
    avatar makes contact with the object
  • The corners of the bounding box of 3D objects and
    the center point of the surface

Element Reference Values
Position Front, Behind, Left, Right, Center
Position LeftFront, RightFront, LeftBehind, RightBehind
Direction Backward, Forward, Left, Right
Direction LeftForward, Rightforward, LeftBackward, Rightbackward
Contact Front, Behind, Left, Right, Top, Bottom, Center
Contact LeftFrontCenter, LeftFrontTop, LeftFrontBottom, RightFrontCenter .
14
Context Element(5/5)
  • Access Group Element
  • Object behavior can be accessed by several user
    types
  • Each user type has different purpose and usage
  • Each group has different access to behavior
    interface
  • DomainType Element
  • Not only internal state of object, but also
    external domain state can effect behavior
    interaction.
  • The same object can behave as a different
    semantic object
  • e.g. A car object in traffic simulation domain
    and assembly training domain
  • DomainType element defines name of domain for
    checking current domain type.

15
Layered Script Language
User
  • Overall structure

Context Menu Interface (Display)
Domain Interface Layer
Avatar-Object Interaction Model
Recording
1st Translator (Task-to-High)
Task-Level Behavior Script
Translating
Motion Sequence Layer
High-level Motion Script
Translating
Application Layer
2nd Translator (High-to-Primitive)
Primitive Motion Script
Primitive Motion Script
Geometric Information
Avatar Low-level Animation Data
Object Low-level Animation Data
Avatar Low-level Animation Data
Object Low-level Animation Data
Application
Application
16
Task-level Behavior Script(1/2)
  • Task-level Behavior Script
  • Presents object and avatar behaviors using XML
    DTD
  • Records and saves user action in temporal
    sequence
  • Extensible representation for behavior set
  • Objects in a domain makeup the usable behavior
    set
  • Cf) existing script which has pre-defined
    behavior DTD
  • Independent from rendering environments
  • Doesnt present appearance of avatar model,
    positional information of virtual objects, so on.

17
Task-level Behavior Script(2/2)
  • Definition of Task-level Avatar-Object Behavior
    Script
  • Template-based Avatar-Object Behavior
    Representation
  • Domain behavior set is flexibly defined by object
    instances
  • Task-level Behavior (Object, Executable-Behavior
    , Narration)

18
High-level Motion Script(1/2)
  • High-level Motion Script
  • Bridges between task-level script and primitive
    motion script
  • Independent from both interface domain and
    application domain
  • Parameterized motion support
  • Synchronization, speed, target, repeat,
    intensity, decay, etc
  • Abstract values rather than physical

19
High-level Motion Script(2/2)
  • Structure of high-level script DTD

20
Primitive Motion Script
  • Primitive motion
  • Supported by rendering engine or motion library
  • Represented in physical parameter values
  • ex) Geometric values such as coordinates of
    avatar and objects, radian value of avatar
    direction, etc
  • Parameters are transmitted to animation engine to
    play animation scenario on screen

21
Script Translators(1/4)
  • Task-level Behavior Script Translator
  • Translates task-level behavior script into
    high-level motion script
  • Consisted of motion sequences to perform
    task-level behaviors
  • Motion planning by task planner and generate the
    sequences
  • ex) ltget targetbox/gt
  • 1. lthighLevelMotion namewalk gt
  • 2. lthighLevelMotion namebend_bodygt
  • 3. lthighLevelMotion namegrabgt
  • Uses logical application domain knowledge
  • According to formal translation model, script of
    each domains is converted to a high-level motion
    script

22
Script Translators(2/4)
  • Formal Task Translation Model
  • Identification of target
  • find location of target object(Lo)
  • Locomotive motion (Ml)
  • identification of present avatar location (La)
  • spatial distance between La and Lo
  • generate Lm, if La ? Lo
  • Manipulative motion (Mm)
  • generate Mm for Lo
  • Verbal information (Vi)
  • generate verbal speech for avatar behavior if
    available
  • Speed and intensity parameters
  • parameterize Mm and Ml for speed, intensity and
    duration

23
Script Translators(3/4)
  • Procedure modules

Ex) Generated high-level motion lthighLevelMotion
name"wave" type"gesture"gt ltspatialParamgt
ltdirection type"object"gt
ltobjectNamegtstudentslt/objectNamegt
lt/directiongt lt/spatialParamgt
lttemporalParamgt ltspeedgtnormallt/speedgt
ltrepeatgtdefaultlt/repeatgt ltdurationgtdefaultlt/
durationgt lt/temporalParamgt ltdegreeParamgt
ltintensitygtnormallt/intensitygt
ltdecaygtdefaultlt/decaygt ltprioritygtnormallt/pri
oritygt lt/degreeParamgt ltverbalParamgt
ltspeechgtLet's do it next time!lt/speechgt
lt/verbalParamgt lt/highLevelMotiongt
24
Script Translators(4/4)
  • High-level Motion Script Translator
  • Major module Object geometric information
    analyzer
  • Calculates location, size, and direction of
    virtual objects
  • Current status of avatar position and posture
  • Translates abstract parameters of high-level
    script to physical values

25
System Implementation(1/2)
  • Creating a scenario script

26
System Implementation(2/2)
  • Running a scenario script in different
    environments
  • Different physical properties of virtual objects
  • Applying same task-level script to other
    applications

OpenGL Application
2D Web Application(MSAgent)
27
Empirical Evaluation(1/3)
  • 23 Users were asked to do the 20 tasks
    pre-defined in video material and text handouts
  • Features
  • Time to finish each test
  • Ratio of achieved tasks
  • Groups and Systems
  • G1 Novice users(12)
  • G2 Expert users(11)
  • S1 Proposed method
  • S2 Proposed method w/o context element
  • S3 Alice system(comparatively lower behavior
    representation)
  • Analysis
  • One-way ANOVA (analysis of variance)

28
Empirical Evaluation(2/3)
  • Results

Group 1 (Novice)
Group 2 (Expert)
29
Empirical Evaluation(3/3)
  • Lesson Learned
  • Using abstract task-level behavior, both a novice
    and expert user achieved high accuracy and fast
    scripting performance.
  • Expert users made the better result in Alice
    system than novice users
  • Expert users showed a tradeoff in Alice system
  • Those of who spent much time made almost same
    task achievement ratio to the proposed system
  • However, the proposed system could save much time
  • Both group answered that context behavior menu
    helped in creating scenario
  • Novice user prefers abstract behavior, while some
    expert user tends to prefer primitive motion for
    detail manipulation

30
Conclusion
  • Conclusion
  • The proposed method consisted of 3 layered script
    languages and object interaction model
  • Avatar-object task-level behavior, abstracts from
    low-level concept to make script easier
  • By separating interface and application, the
    script can be reused in various environments
  • Novice user can create scenario with less effort
    and prefer the proposed method

31
Current Research Interests Avatar Augmented
Annotation Interface for e-Learning
  • Introduction
  • E-Learning, web-based teaching (WBT), and
    distance learning
  • learn in their own spaces and times
  • Interactions between students and teachers
    provide more educational effect
  • Without interactions, students become bored with
    online coursework
  • Interaction techniques
  • Video and animation clips
  • Animated Pedagogical Agent
  • Annotations(Digital Ink)

32
Current Interests Avatar Augmented Annotation
Interface for e-Learning
  • Animated Pedagogical Agent
  • The main advantage of classroom instruction over
    distance education
  • Persona Effect
  • Gestures performed in live instruction
  • Many systems have been studied
  • CTA, MASH, Wizlow, PPP, Steve, and etc
  • Creating these avatar-augmented presentations
  • Usually laborious and time consuming
  • Easy and intuitive authoring interface technique
    is needed

33
Current Interests Avatar Augmented Annotation
Interface for e-Learning
  • Annotation (digital inking)
  • an important feature of a digital lecture or
    presentation system
  • Annotation or Digital inking can capture the
    knowledge between student and teacher and easily
    share and reuse material
  • AnnotatED, OATS, Xlibris, Intelligent Pen, etc

34
Current Research Interests Avatar Augmented
Annotation Interface for e-Learning
  • Avatar augmented annotation
  • Enhances learning effects by integrating these
    two functionalities avatar and annotation
  • To author animated lecture contents
  • To mark up the presentation using freehand
    annotations
  • Reduce costs of controlling avatar animation
  • Author and user created narrative scenarios

Avatar Animation Scenario
End-User
Freehand Annotation Interface
Integrating Framework
Author/User
35
Current Research Interests Avatar Augmented
Annotation Interface for e-Learning
  • Overall structure of the proposed system

Scenario Script
Animated Content
Annotation Model
Free-Hand Gesture
Animation Model
Motion Library
Users Interface
Menu
Context Model
Original Web Document
36
Current Research Interests Avatar Augmented
Annotation Interface for e-Learning
  • Main components
  • Annotation model
  • Recognize free-hand annotation types
  • Menu-based annotation types
  • Context model
  • Structure information of web documents
  • Annotated position in Xlink/Xpath
  • HTML/XML tag information of annotated area
  • Animation model
  • Animation list
  • Animation decision rules
  • Assign animation to annotation, according to each
    annotation types defined in annotation and
    context models

37
Current Research Interests Avatar Augmented
Annotation Interface for e-Learning
  • Summary
  • Still at the early proposal stage
  • Working on defining the models and implementing
    interfaces
  • Continue it as an individual research during
    post-doc period
  • Considering co-work with other related systems
  • Applying pen-based interface to OATS or AnnotatED
  • Agent interface for semantic navigation or
    recommendation system
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