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Deformable Ray-Casting Interaction Technique


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									Deformable Ray-Casting
 Interaction Technique

          YVR 2005 Pohang – 02/25/2005

          Ludovic Sternberger
          directed by Pr. D. Bechmann
Presentation Outline

   Introduction
    –   Research interests
    –   Previous works
    –   Pros and cons on virtual pointer techniques
    –   Hopped characteristics for the deformable ray-cast
   The deformable ray-casting metaphor
    –   Overview
    –   Selection
    –   Navigation
   Future works

   Research Interests
    –   Environment : Workbench, Data Gloves
    –   Goals
            simple metaphors, natural & intuitive interaction
             techniques, using gestures, speak recognition, …
            test them on real life applications (3D Geometric
             Constructions, Surgery Training)
            propose a good framework to easily develop 3D UI
    –   A first new metaphor : The Deformable Ray-Cast

   Existing Interaction Techniques
    –   Egocentric
            Virtual Hand (simple, Go-Go and extensions)
            Virtual Pointers (classical, raycasting, spotlight,
            Image-plane based (framing hands, head crusher, sticky
    –   Exocentric
            WIM
            Voodoo Dolls

   Pros and Cons on virtual pointers
    –   PROS
           Fast selections
           Very simple
    –   CONS
           Ambiguity problems when objects are close to each other
           Object of interest occluded by another
           Too small and too far objects

   Hopped characteristics for the deformable ray-cast
    –   Easy selection of occluded objects by going around
    –   Both single or multiple selection
    –   Precise ray-casting technique, both on near and far objects
    –   It reduces the need for disambiguation when two or more
        objects are close to each other
    –   It provides constraint navigation along any curve
    –   It provides planned navigation
    –   Selection and navigation can be achieved in the mean task
The deformable ray-cast

   Overview
    –   The ray is composed with pieces of curve
    –   Manipulation with 2 hands (natural and intuitive)
    –   2 hands = 1 vector
            Length = speed of the ray
            Direction = orientation of the ray
    –   2 gestures / 3 modes
            Moving backward
            Moving forward
            Dead zone
The deformable ray-cast

   Selection
    –   B-Spline with n control points regularly spaced out
    –   The user controls the last part of the curve
            Expand the set of objects to which the user can point
            Reduce the need of disambiguation on objects which
             are close to each other
            Reduce obstructed objects misselected
    –   The ray can pass through several objects
            Multiple selection
The deformable ray-cast

   Navigation
    –   Draw a 3D path for planned navigation
            Play
            Rewind
            …
    –   Provide an equivalent to the cinema’s traveling
        technique to move the camera
            Ex : view inside a body during a virtual surgery operation

   in 3D Geometric Constructions
    –   Selection based on 3D layers
    –   Planned navigation to provide a better
        understanding of 3D constructions
   in Medical Surgery
    –   Navigation inside blood vessels

   Improve the metaphor by adding more visual
    clues inside the scene : shadows, specific
    colors, sounds, …
   Add a second point of view (camera) at the
    end of the ray, displayed in miniature
   Use the deformable ray-cast for manipulation
    : constrained manipulation along the curve.

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