A Hands-On Introduction to
Discrete Differential Operators on Polygon Meshes

Introduction

Photo of Sven D.
                Wagner

Sven D. Wagner

TU Dortmund

Photo of Astrid
                Bunge

Astrid Bunge

AutoForm Engineering

Photo of Mario
                Botsch

Mario Botsch

TU Dortmund

🚀 by Decker

Material is available online

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Material is available online

Problem Setting

Solve PDEs on discrete surface meshes and volume meshes

images/vw.pngSurface mesh images/bunny-tets.pngVolume mesh

Problem Setting

Solve PDEs on discrete surface meshes and volume meshes

We focus on surface meshes

images/vw.pngSurface mesh images/bunny-tets.pngVolume mesh

Differential Operators

  • Gradient (direction of steepest ascent) \[ \small \grad f(u,v) \;=\; \vector{ \pdiff{f}{u} \\ \pdiff{f}{v} } \]
  • Divergence (magnitude of source or sink) \[ \small \func{div}\of{\vec{f}(u,v)} \;=\; \func{div} \vector{f_1(u,v) \\ f_2(u,v)} \;=\; \pdiff{f_1}{u} + \pdiff{f_2}{v} \]
  • Laplace (difference to average of local neighborhood) \[ \small \laplace f(u,v) \;=\; \func{div} \grad f \;=\; \frac{\partial^2 f}{\partial u^2} + \frac{\partial^2 f}{\partial v^2} \]

Diffusion Equation: \(\dot f = \lambda \laplace f\)

Laplace Equation: \(-\laplace f = 0\)

Discrete Laplacian has various applications

  • Mean Curvature
  • Smoothing & Fairing
  • Parameterization
  • Deformation
  • Geodesics Distances
  • …

Simplicial Meshes → Polygon Meshes

images/vw.pngSurface Meshes: Triangles Polygons images/bunny-tets.pngVolume Meshes: Tetrahedra Polyhedra

Artist-Made Polygon Meshes

Outline

  • Part 1: Triangle Meshes (09:00–10:30)
    • Introduction
    • Laplacian on Triangle Meshes
    • Coding: Parameterization
    • Robust Laplacians on Triangle Meshes
    • Coding: Parameterization
  • Part 2: Polygon Meshes (10:45–12:15)
    • Laplacian on Polygon Meshes
    • Coding: Smoothing
    • Robust Polygon Laplacian
    • Coding: Geodesics in Heat
    • Other Polygon Laplacians

Please ask question at any time!