An Intelligent User Interface with Motion Planning for 3D Navigation

1
An Intelligent User Interface with Motion
Planning for 3D Navigation

• Tsai-Yen Li and Hung-Kai Ting
• Computer Science Department, National Chengchi
  University
• Taipei, Taiwan
• Shih-Chung Jessy Kang

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3D Navigation

• Interactive 3D graphics is becoming popular on
  desktop personal computers.
• VRML browser WALK mode

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Difficulties in Current Technology

• Difficulties in 3D Navigation
• Using 2D mouse to navigate in 3D environment is a
  nightmare for novice users.
• Precise navigation control is difficult to
  achieve with low frame rates

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Traditional 3D User Interface
V
Vy

• How to navigate in 3D environment by 2D mouse?
• User drags a velocity vector v
• Decompose v into vx, vy
• Vx refers to rotational velocity
• Vy refers to linear velocity forward and backward
• Move view point (camera)

Vx
Vx
Vy
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Traditional 3D User Interface

• Potential Problem in the Mouse Control
• If there is potential collisiongt stop
• User may be stuck in certain location, and need
  to move backward first to escape

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Solutions

• Predict users intention
• Generate a roadmap automatically to help users
  avoid unnecessary maneuvers due to collisions
  with the environment

Integrate road map planner in 3D navigation
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Intelligent 3D User Interface

• Predict Users Intention
• No modification A1, A2
• Direct modification B1, B2
• Indirect modification C

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Intelligent 3D User Interface (cont.)

• Computing Smooth Maneuver Path
• Trivial path straight line path, A1
• Non-Trivial path no straight line, A2
• No path no actions

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Implementation

• Modify VRML browser based on Java3D SDK library
• The routine for processing mouse events
• The routine for updating next viewpoint
  configuration
• Randomized Roadmap Planner
• Pre-compute C-space obstacle with linear-time
  algorithm. (Lozano-Perez 1983)
• Store in 3D bitmap 128x128x128
• Divide C-space into 8x8x8512 regions and sample
  up to 4 free configurations in each region.
• Give up sampling in each region after 20 trials.
• Connect all pairs of nodes in the same or
  neighboring regions

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Experiment Setting

• Regular PC with a Celeron 300A processor
• WALK mode in VRML browsers
• 10 testers
• 6 CS major students
• 2 are familiar with VRML browser
• 2 do not use computer regularly.

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Experiment Setting

• 6 checking points in maze-like environment
• A bouncing ball helps user identify check point
• A 2D layout provides for testers

VRML browser
2D-layout map of the maze
Top View of Maze Environment
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Experiment Result
Planner-generated non-trivial paths
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Experiment Result
Comparison of navigation efficiency w/ and w/o
path planning

• Performance speed up about 73
• Save 1/3 navigation steps

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Experiment Analysis
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Conclusion

• A path planner with a randomized roadmap approach
  is used to assist a user in navigating through
  difficult areas where a user often get stuck with
  traditional user interfaces.
• The researchers believe that this intelligent
  user interface is effective because
• it can generate the geometric reasoning tasks
  while retaining the advantages of direct
  manipulation.

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Future Work

• Consider dynamic and unbounded workspace with
  incremental roadmap construction.
• Extend to
• Different tasks
• Different virtual scenes
• Different systems of various computing powers.

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Thank You