A soft hand model for physically based manipulation of virtual objects
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A Soft Hand Model for Physically-based Manipulation of Virtual Objects. Jan 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.

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A soft hand model for physically based manipulation of virtual objects
A Soft Hand Model for Physically-based Manipulation of Virtual Objects

Jan 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.


Outline
Outline Virtual Objects

  • Background

  • Introduction

  • Related Work

  • System Design

  • Results and Discussion

  • Conclusions

  • Future Work


Background
Background Virtual Objects

  • What is VR?

    • Virtual Reality

  • Applications of VR

    • Video Games

    • Training Systems

    • Simulator

    • 3D/4D Movies, Games

    • Auto Design


Background1
Background Virtual Objects

  • 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.


Introduction
Introduction Virtual Objects

  • 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.


Introduction1
Introduction Virtual Objects

  • 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.


Introduction2
Introduction Virtual Objects

  • Real World Grasping

Increasing contact area with increasing contact force.

Left: loose touch.

Right: strong pressure between finger and a pane of glass.


Introduction3
Introduction Virtual Objects

  • 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


Introduction4
Introduction Virtual Objects

  • 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.


Related work
Related Work Virtual Objects

  • 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].


System design
System Design Virtual Objects

  • Software Architecture

  • Tracking

  • Hand Model


System design1
System Design Virtual Objects

  • Software Architecture

    • Scenegraph System: OpenSG

    • Physics Engine: bullet

    • User Input


System design2
System Design Virtual Objects

  • Tracking

    • An optical finger tracking system

    • Seven evenly spread cameras for a 3m3 volume


System design3
System Design Virtual Objects

  • Hand Model

    • A rigid body (grey)

    • A soft body (green)


Results and discussion
Results and Discussion Virtual Objects

  • Unconstrained interaction with a horse model. The fingerpads adapt to the geometries’ shape, enabling stable and robust interaction.


Results and discussion1
Results and Discussion Virtual Objects

  • Two handed interaction with non-constrained objects. Collision response between torus and stick is enabled through physics simulation.


Results and discussion2
Results and Discussion Virtual Objects

  • Interaction within an immersive display system. A user interacts with a constrained steering wheel using both hands, thus reproducing a real-world interaction.


Conclusions
Conclusions Virtual Objects

  • 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


Future work
Future Work Virtual Objects

  • A soft body for palm

  • Using different deformation algorithm depending on the situation

  • A skinned hand representation


References
References Virtual Objects

  • [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.


Thank you
Thank you! Virtual Objects

  • Questions?


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