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A Soft Hand Model for Physically-based Manipulation
of Virtual ObjectsJan Jacobs
Group Research Virtual Technologies
Volkswagen AG
Bernd Froehlich
Virtual Reality Systems Group
Bauhaus-Universitat Weimar
In Virtual Reality Conference (VR), 19 - 23 March, 2011 Singapore, IEEE, 2011.
Graduate Programs in Computer Sciencehttp://www.cs.utsa.edu
Outline
Background
Introduction
Related Work
System Design
Results and Discussion
Conclusions
Future Work
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Background
What is VR? Virtual Reality
Applications of VR Video Games Training Systems Simulator 3D/4D Movies, Games Auto Design
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Background
The integration of physical behavior has significantly increased the quality of games and virtual environments overall
The interaction with simulated objects also needs to occur on a physical basis.
The representation of a user in the virtual world needs to be physically modeled to achieve a realistic interaction between user and virtual objects.
The problem: the modeling of the finely articulated human hand to enable finger-based interaction.
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Introduction
A direct and robust finger-based manipulation relies on three major issues Stable grasping of objects Robust manipulation Controlled releasing of objects.
In general, there are two common ways to achieve these goals Grasping through heuristics Collision based physical simulations.
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Introduction
In 2005, Borst et al. [1] relies on a hand model constructed from rigid bodies.
Problems: It could not correctly consider friction
between fingers and virtual It required careful tuning of parameters for a
reasonably stable interaction.
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Introduction Real World Grasping
Increasing contact area with increasing contact force. Left: loose touch. Right: strong pressure between finger and a pane of glass.
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Introduction
Physics problem f = μN μ is the friction coefficient N is the pressure The friction doesn’t related to the contact area
VR Simulation No haptic system Mapping: the higher the pressure, the bigger the contact area
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Introduction
A soft body model for each finger phalanx was introduced to enable pressure-based deformation of the soft finger contact areas.
The system allows for very precise and robust finger-based grasping, manipulation and releasing of virtual objects in real-time.
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Related Work
This idea is originally from Duriez et al. in 2008 [2]. They addressed this problem by directly calculating friction at skin level. Complexity
The FastLSM algorithm by Rivers et al. [3].
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System Design
Software Architecture
Tracking
Hand Model
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System Design
Software Architecture Scenegraph System: OpenSG Physics Engine: bullet User Input
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System Design
Tracking An optical finger tracking system Seven evenly spread cameras for a 3m3 volume
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System Design
Hand Model A rigid body (grey) A soft body (green)
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Results and Discussion
Unconstrained interaction with a horse model. The fingerpads adapt to the geometries’ shape, enabling stable and robust interaction.
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Results and Discussion
Two handed interaction with non-constrained objects. Collision response between torus and stick is enabled through physics simulation.
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Results and Discussion
Interaction within an immersive display system. A user interacts with a constrained steering wheel using both hands, thus reproducing a real-world interaction.
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Conclusions
A new hand model is based on soft bodies coupled to a rigid body hand skeleton Precise and robust finger-based grasping, manipulation and
releasing Dynamic adaptation of the stiffness values The implicit friction model
The pressure-based increasing and decreasing of the contact area of the simulated finger phalanxes
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Future Work
A soft body for palm
Using different deformation algorithm depending on the situation
A skinned hand representation
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References
[1] C. W. Borst and A. P. Indugula. Realistic virtual grasping. In Virtual Reality Conference (VR), 2005 IEEE, pages 91–98, 320, 2005.
[2] C. Duriez, H. Courtecuisse, J. P. de la Plata Alcalde, and P.-J. Bensoussan. Contact skinning. In Eurographics 2008 (short paper), pages 313–320, New York, NY, USA, 2008.
[3] A. R. Rivers and D. L. James. FastLSM: Fast lattice shape matchingfor robust real-time deformation. ACM Transactions on Graphics (Proc. SIGGRAPH 2007), 26(3):82, July 2007.
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