Robust iso-surface tracking for interactive character skinning

We present a novel approach to interactive character skinning, which is robust to extreme character movements, handles skin contacts and produces the effect of skin elasticity (sliding). Our approach builds on the idea of implicit skinning in which the character is approximated by a 3D scalar field and mesh-vertices are appropriately re-projected. Instead of being bound by an initial skinning solution used to initialize the shape at each time step, we use the skin mesh to directly track iso-surfaces of the field over time. Technical problems are two-fold: firstly, all contact surfaces generated between skin parts should be captured as iso-surfaces of the implicit field; secondly, the tracking method should capture elastic skin effects when the joints bend, and as the character returns to its rest shape, so the skin must follow. Our solutions include: new composition operators enabling blending effects and local self-contact between implicit surfaces, as well as a tangential relaxation scheme derived from the as-rigid-as possible energy to solve the tracking problem.

[1]  Michael Gleicher,et al.  Building efficient, accurate character skins from examples , 2003, ACM Trans. Graph..

[2]  Olga Sorkine-Hornung,et al.  Context‐Aware Skeletal Shape Deformation , 2007, Comput. Graph. Forum.

[3]  Olga Sorkine-Hornung,et al.  Locally Injective Mappings , 2013 .

[4]  Jirí Zára,et al.  Spherical blend skinning: a real-time deformation of articulated models , 2005, I3D '05.

[5]  John Hart,et al.  ACM Transactions on Graphics , 2004, SIGGRAPH 2004.

[6]  Ronald Fedkiw,et al.  Robust quasistatic finite elements and flesh simulation , 2005, SCA '05.

[7]  Olga Sorkine-Hornung,et al.  Smooth Shape‐Aware Functions with Controlled Extrema , 2012, Comput. Graph. Forum.

[8]  Brian Wyvill,et al.  Implicit Decals: Interactive Editing of Repetitive Patterns on Surfaces , 2014, Comput. Graph. Forum.

[9]  Ilya Baran,et al.  Automatic rigging and animation of 3D characters , 2007, SIGGRAPH 2007.

[10]  Marc Alexa,et al.  As-rigid-as-possible surface modeling , 2007, Symposium on Geometry Processing.

[11]  Loïc Barthe,et al.  Adequate inner bound for geometric modeling with compact field functions , 2013, Comput. Graph..

[12]  Brian Wyvill,et al.  Implicit skinning , 2013, ACM Trans. Graph..

[13]  George Papagiannakis,et al.  Modeling of bodies and clothes for virtual environments , 2004, 2004 International Conference on Cyberworlds.

[14]  Paul S. Heckbert,et al.  Using particles to sample and control implicit surfaces , 1994, SIGGRAPH.

[15]  Brian Wyvill,et al.  A Gradient-Based Implicit Blend , 2012 .

[16]  Marie-Paule Cani,et al.  Anatomy transfer , 2013, ACM Trans. Graph..

[17]  Hans-Christian Rodrian,et al.  Dynamic Triangulation of Animated Skeleton-Based Implicit Surfaces , 1996 .

[18]  Antoine Bouthors,et al.  Twinned meshes for dynamic triangulation of implicit surfaces , 2007, GI '07.

[19]  JungHyun Han,et al.  Bulging‐free dual quaternion skinning , 2014, Comput. Animat. Virtual Worlds.

[20]  Jan Bender,et al.  Efficient GPU Data Structures and Methods to Solve Sparse Linear Systems in Dynamics Applications , 2013, Comput. Graph. Forum.

[21]  Ryan Schmidt,et al.  On the velocity of an implicit surface , 2011, TOGS.

[22]  Milan Sonka,et al.  Image Processing, Analysis and Machine Vision , 1993, Springer US.

[23]  Marie-Paule Cani,et al.  An implicit formulation for precise contact modeling between flexible solids , 1993, SIGGRAPH.

[24]  John P. Lewis,et al.  Pose Space Deformation: A Unified Approach to Shape Interpolation and Skeleton-Driven Deformation , 2000, SIGGRAPH.

[25]  Olivier Dionne,et al.  Geodesic Binding for Degenerate Character Geometry Using Sparse Voxelization , 2014, IEEE Transactions on Visualization and Computer Graphics.

[26]  Mark Meyer,et al.  Discrete Differential-Geometry Operators for Triangulated 2-Manifolds , 2002, VisMath.

[27]  Alexei Sourin,et al.  Function representation in geometric modeling: concepts, implementation and applications , 1995, The Visual Computer.

[28]  Brian Wyvill,et al.  Extending the CSG Tree. Warping, Blending and Boolean Operations in an Implicit Surface Modeling System , 1999, Comput. Graph. Forum.

[29]  Theodore Kim,et al.  Simulating articulated subspace self-contact , 2014, ACM Trans. Graph..

[30]  Olga Sorkine-Hornung,et al.  Elasticity-inspired deformers for character articulation , 2012, ACM Trans. Graph..

[31]  Eftychios Sifakis,et al.  Efficient elasticity for character skinning with contact and collisions , 2011, ACM Trans. Graph..

[32]  CaniMarie-Paule,et al.  Robust iso-surface tracking for interactive character skinning , 2014 .

[33]  Olga Sorkine-Hornung,et al.  Bounded biharmonic weights for real-time deformation , 2011, Commun. ACM.

[34]  Jirí Zára,et al.  Geometric skinning with approximate dual quaternion blending , 2008, TOGS.

[35]  Jerry L. Prince,et al.  Snakes, shapes, and gradient vector flow , 1998, IEEE Trans. Image Process..

[36]  Eugene Fiume,et al.  Anatomically-based models for physical and geometric reconstruction of humans and other animals , 2001 .

[37]  Brian Wyvill,et al.  Implicit Blending Revisited , 2010, Comput. Graph. Forum.

[38]  Kai Hormann,et al.  Mean value coordinates for arbitrary planar polygons , 2006, TOGS.

[39]  A. Ricci,et al.  A Constructive Geometry for Computer Graphics , 1973, Computer/law journal.