CS326 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

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

CS326 3 Difficulties in Current Technology Difficulties in 3D Navigation: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

CS326 4 Traditional 3D User Interface How to navigate in 3D environment by 2D mouse?How to navigate in 3D environment by 2D mouse? 1.User drags a velocity vector v 2.Decompose v into v x, v y 3.V x refers to rotational velocity 4.V y refers to linear velocity forward and backward 5.Move view point (camera) V VxVx VxVx VyVy VyVy

CS326 5 Traditional 3D User Interface Potential Problem in the Mouse ControlPotential Problem in the Mouse Control 1.If there is potential collision=> stop 2.User may be stuck in certain location, and need to move backward first to escape

CS326 6 Solutions 1.Predict users’ intention 2.Generate a roadmap automatically to help users avoid unnecessary maneuvers due to collisions with the environment Integrate road map planner in 3D navigation

CS326 7 Intelligent 3D User Interface Predict Users’ IntentionPredict Users’ Intention A.No modification: A1, A2 B.Direct modification: B1, B2 C.Indirect modification: C

CS326 8 Intelligent 3D User Interface (cont.) Computing Smooth Maneuver PathComputing Smooth Maneuver Path A.Trivial path: straight line path, A1 B.Non-Trivial path: no straight line, A2 C.No path: no actions

CS326 9 Implementation Modify VRML browserModify VRML browser based on Java3D SDK library mouse events 1.The routine for processing mouse events viewpoint configuration 2.The routine for updating next viewpoint configuration Randomized Roadmap PlannerRandomized Roadmap Planner 1.Pre-compute C-space obstacle with linear-time algorithm. (Lozano-Perez 1983) 2.Store in 3D bitmap 128x128x128 3.Divide C-space into 8x8x8=512 regions and sample up to 4 free configurations in each region. 4.Give up sampling in each region after 20 trials. 5.Connect all pairs of nodes in the same or neighboring regions

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

CS checking points in maze-like environment A bouncing ball helps user identify check point A 2D layout provides for testers Experiment Setting 2D-layout map of the maze VRML browser Top View of Maze Environment

CS Experiment Result Planner-generated non-trivial paths

CS Experiment Result Comparison of navigation efficiency w/ and w/o path planning Performance speed up about 73% Save 1/3 navigation steps

CS Experiment Analysis

CS 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.

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

CS Thank You