Using Collaborative Interactive Using Collaborative Interactive Objects and Animation to Objects and Animation to

Enable Dynamic Interactions in Enable Dynamic Interactions in Collaborative Virtual Collaborative Virtual

EnvironmentsEnvironments

Pieter Jorissen* Maarten Wijnants, Wim

Lamotte

OverviewOverview

Interactions in CVEs Interactive Objects approach Avatars in CVEs Creating more flexible avatar interaction User input Network setup Network traffic Results Future Work

Collaborative Virtual Collaborative Virtual Environments (CVEs)Environments (CVEs)

Immersive 3D World Multiple participants (distributed) Users can interact through an avatar

Navigate Interact with objects/other users

Avatar represents the user and their interactions Position/orientation (3D model) Interactions (animations) (other: personality, emotion,…)

Interactions in CVEsInteractions in CVEs

Traditional Navigation Direct interaction techniques for actor -

object interactions Advanced behavior = case specific Hard-coded in application

Result: Not very flexible Not runtime extensible Little reusability

Interactions in CVEsInteractions in CVEs

GoalGoal

Make CVE worlds more interactive

Generalize CVE interactions Make interactions independant of the application Allow new objects to be introduced at any time Make no distinction between different kinds of

object interactions (avatars, objects, AI agents) Allow every object/avatar to interact with every

other object/avatar in the world

Single scheme for all CVE interactions

Keep netwerk traffic as low as possible

Our Approach Our Approach

Put interaction info and behaviors in the object description

Describe behaviors in parameterized scripts

Put only the general interaction scheme in the application (script handling, communication)

Interaction layer communicates with the objects

Objects can communicate with other objectsthrough links and messages

Our ApproachOur Approach

Interactive Object Interactive Object DescriptionDescription

Object Properties Parts, transformations, models, id,

constraints,… Interaction Properties

Commands, triggers, interaction zones Object Behaviors

Scripts Trigger – script coupling

XML Easy to read, easy to understand

Interaction LayerInteraction Layer

Interactive WorldsInteractive Worlds

Advantage Objects/parts are easy to modify (runtime) Objects/parts are easy to reuse New objects can be introduced at any time Interaction information could be used for

planning Information can be used for network

optimizations Disadvantage

More work in the modeling stage Less programming (more scripting) High reusability of object description

Avatars in CVEs Avatars in CVEs Evolution:

Avatar is the users means of interaction

Proper avatar animation increases feeling of immersion

Avatar Animation in CVEsAvatar Animation in CVEs

Skeletal animation + Keyframed actions

Advantages Low memory use Computationally inexpensive

Disadvantages Lack of flexibility (fixed set of animations)

More flexibility => Use inverse kinematics Very flexible Computationally more expensive

Adding IK to the CVE Adding IK to the CVE avataravatar

“Arm” movement (grasping, pointing, pushing,...)

Store IK info separate from animated model IK joint chain End effector Joint constraints Joint reach (bounding box)

Not human avatar specific !!! Direct control

User InputUser Input Direct 3D input Keyboard

Slow Unintuitive Difficult context switch No reference

Microscribe-3D Easy context switch Intuitive => fast No force feedback

Network setupNetwork setup

Network TrafficNetwork Traffic

Startup: get world from server TCP Updates: UDP + multicast

Keep it as low as possible!!! Use interactive object information (at server)

Object/part constraints determine possible moves Animation

Send only high level description (animID, start, stop) Animation synchronization not perfect, but

unnecessary Inverse Kinematics

Send only position of end effector Calculate joints locally (no perfect synch for all joints)

ResultsResults

Collaborative World 1

Hand interaction 1

Hand Interaction 2

Future WorkFuture Work

Adding AI agents

Large scale testing

Coupling to physical simulation engine

Head tracking + Stereo vision

Add force feedback

Usability study

QUESTIONS ?QUESTIONS ?