Multiuser Virtual Gaming with Assisted Feedback Mechanisms

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Multi-user Virtual Gaming with Assisted Feedback
Mechanisms
CAD/Graphics2001, August 22-24, Kunming
Hanqiu Sun1, K.M. Leung1, W.C. Wang2 and K.Y.
Sit1 1Department of Computer Science and
Engineering, The Chinese University of Hong
Kong 2Institute of Software, Academia Sinica,
Beijing

• Presenter Dr. Hanqiu Sun

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Outline

• 1.Introduction
• 2.Multi-user Virtual Ping-Pong System
• Client-Server framework
• Networked programming environment
• Multi-user virtual ping-pong server
• Multi-user virtual ping-pong client
• Assisted performance with feedback mechanisms
• 3.Conclusion

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1.Introduction

• 3D multiplayer games are popular
• No game developer use VRML
• Few systems evaluate feedback mechanisms on VRML
• This paper
• multiplayer virtual gaming on VRML and Java
• evaluate feedback mechanisms

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1.Introduction

• Have to utilize VRML control and Java language
• VRML does not have network capability
• Java enables network access
• Multi-user virtual ping-pong system
• coordinating user interactions
• dynamic gaming behavior
• real-time scene display
• multi-user gaming on Internet
• evaluating multi-sensory feedback mechanisms

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2.1 Client-Server framework
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2.1 Client-Server framework

• Ping-pong server
• creation and deletion of players
• send all events to all related clients
• manage game logic
• ensure game status consistency
• Ping-pong clients
• GUI for players to interact
• game scene managed by VRML
• control panel by Java - communicate through
  messages, create and join game

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2.1 Client-Server framework
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2.2 Networked Environment

• Build serve and client by Java 2 SDK
• most web browsers support Java version 1.1 only
• Java 2 new features RMI callback, Swing cannot
  be used
• Ping-Pong client
• Forte in constructing user interface
• access objects in VRML scene through External
  Authoring Interface (EAI)

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2.2 Networked Environment

• Ping-Pong server
• due to the universality of Java, further
  development is independent of OS
• Current system developed on
• broadband internet
• 100Mbit Ethernet

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2.3 Virtual Ping-Pong server

• Basic functions performed similar to typical
  network applications
• continuously listens to server socket
• when connection request received, create socket
  and a thread to handle incoming network
  connections
• The rest of server composed of
• ping-pong players manager
• ping-pong table manager
• ping-pong ball manager

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2.3 Virtual Ping-Pong server

• Ping-Pong players manager
• name, connection ID, table, bat ID
• holds all online players information
• as a critical section since multiple players may
  update at the same time
• connection ID indicates its role in game player
  or spectator
• handles 2 kinds of player remote and computer
  players

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2.3 Virtual Ping-Pong server

• For remote players,
• receive bat status (position, orientation) from
  them
• store and replicate the packets, then send to
  other players and spectators
• redirect messages between players
• For computer players,
• continuously traces the ball according to its
  bats position, the balls position and its speed

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2.3 Virtual Ping-Pong server

• Ping-Pong table manager
• keep track of the number and current status of
  opened Ping-pong games
• e.g. which players are on a table
• can support at most 20 games simultaneously

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2.3 Virtual Ping-Pong server

• Ping-Pong ball manager
• calculate the balls new position
• check if player hits the ball
• change ball direction after a hit
• evaluate game result
• stop the ball if it is out of table or it hits
  table more than once on the same side
• dispatch its position and game score to all
  players

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2.4 Virtual Ping-Pong client

• Bat rotation
• controlled by joystick
• After the ball is hit by a bat (collision),
• its speed is proportional to bat angle and the
  coming speed of the ball
• its direction depends on the rotated angle of the
  bat

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2.4 Virtual Ping-Pong client
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2.4 Virtual Ping-Pong client

• Update scoreboard
• interface to VRML browser for scene display
• communicate with server
• capture joystick information

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2.5 Feedback Mechanisms

• Most previous investigation targets static scenes
• Little work done on dynamic environment like this
• 3 major feedback mechanisms can be adopted
• visual feedback
• audio feedback
• force/tactile feedback

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2.5 Feedback Mechanisms

• Within the context of Ping-pong system
• Visual and audio feedback are tested for gaming
  performance
• they are directly supported by VRML standard

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2.5 Feedback Mechanisms

• Visual Feedback
• includes following factors
• field of view
• graphics refresh rate
• convergence angle
• image spatial resolution
• depth perception
• color discrimination
• lighting level

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2.5 Feedback Mechanisms

• Visual Feedback (contd)
• 3 factors are considered
• Color discrimination
• ball is green in color
• a cold color to make the ball size appear smaller
• make the game more difficult to play

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2.5 Feedback Mechanisms

• Visual Feedback (contd)
• Lighting Level
• light up the environment by directional light
• shows less specular effect
• Depth perception
• project ball shadow on the table
• a red cross centered at the ball as a 3D cue
• can be switched on/off

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2.5 Feedback Mechanisms

• Audio Feedback
• Passive audio feedback
• reinforce the realism of simulation
• arise user awareness of a change in scene
• sound of winning and losing point in game
• clapping hand and exclamation sound when the
  player wins or loses a point

They are passive because the boards have present
enough game informatione
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2.5 Feedback Mechanisms

• Audio Feedback (contd)
• Active audio feedback
• sound generated by some equipment
• a ping sound when a player strikes the ball by
  a bat (equipment)
• another ping sound when the ball hits the table

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2.5 Feedback Mechanisms

• Audio Feedback (contd)
• Enhanced audio feedback
• sound that is dynamically changed according to
  the virtual world context
• an interval beep sound produced virtually from
  the ball
• player can distinguish how far and position
  (left/right) of the ball
• useful in depth perception

Also can be switched on/off
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2.5 Feedback Mechanisms

• Experiments
• to investigate the usefulness of visual and audio
  feedbacks in players performance in the game
• 20 undergraduate students invited
• each one plays the simplified version of the game
  in a particular setting

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2.5 Feedback Mechanisms

• Experiments (contd)
• participants are randomly divided into 4 group,
  corresponds to 4 game settings
• Neutral test no additional visual or audio
  feedback provided
• Visual test only visual feedback
• Audio test only audio feedback
• Integrated test both feedbacks are provided

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2.5 Feedback Mechanisms

• Experiments (contd)
• Evaluation index participants hit rate
• the number of times a user successfully hits the
  ball over the number of times a user has a chance
  to hit the ball

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2.5 Feedback Mechanisms
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2.5 Feedback Mechanisms
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2.5 Feedback Mechanisms
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2.5 Feedback Mechanisms
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2.5 Feedback Mechanisms
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2.5 Feedback Mechanisms

• Facts observed from results
• users perform better with the aid of audio
  feedback
• active and enhanced feedback determine and
  predict ball position, concentrate more on the
  game
• passive feedback make users more willing to win
  the game

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2.5 Feedback Mechanisms

• Additional visual feedback introduces negative
  feedback on performance
• give more information on ball position but
  increase scene complexity at the same time
• users have to process a more complex scene in a
  short time
• fail to predict the moving ball position before
  it arrives

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3.Conclusion

• Developed a multi-player virtual gaming system
  using standard VRML and Java
• supports the virtual construction of multi-user
  Ping-pong game
• dynamic behavior of gaming
• incorporation of feedback mechanism in assisting
  task performance

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3.Conclusion

• Conducted sets of experiments
• measure the effectiveness of visual and auditory
  feedback mechanisms in interactive task
  performance
• additional audio feedback introduces improvement
  in game playing
• additional visual feedback incurs negative effect
• important guidance for designing effective
  web-based VR gaming systems