Deforming meshes that split and merge

Chris Wojtan, Nils Thürey, Markus Gross, Greg Turk

Research output: Contribution to journalConference articlepeer-review

107 Scopus citations


We present a method for accurately tracking the moving surface of deformable materials in a manner that gracefully handles topological changes. We employ a Lagrangian surface tracking method, and we use a triangle mesh for our surface representation so that fine features can be retained. We make topological changes to the mesh by first identifying merging or splitting events at a particular grid resolution, and then locally creating new pieces of the mesh in the affected cells using a standard isosurface creation method. We stitch the new, topologically simplified portion of the mesh to the rest of the mesh at the cell boundaries. Our method detects and treats topological events with an emphasis on the preservation of detailed features, while simultaneously simplifying those portions of the material that are not visible. Our surface tracker is not tied to a particular method for simulating deformable materials. In particular, we show results from two significantly different simulators: a Lagrangian FEM simulator with tetrahedral elements, and an Eulerian grid-based fluid simulator. Although our surface tracking method is generic, it is particularly well-suited for simulations that exhibit fine surface details and numerous topological events. Highlights of our results include merging of viscoplastic materials with complex geometry, a taffy-pulling animation with many fold and merge events, and stretching and slicing of stiff plastic material.

Original languageEnglish
Article number76
JournalACM Transactions on Graphics
Issue number3
StatePublished - 27 Jul 2009
Externally publishedYes
EventACM SIGGRAPH 2009, SIGGRAPH '09 - New Orleans, LA, United States
Duration: 3 Aug 20097 Aug 2009


  • Deformable meshes
  • Fluid simulation
  • Physically based animation
  • Topological control


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