Sculpting multi-dimensional nested structures

1. Sculpting multi-dimensional nested structures - Lucian Stanculescu a,b Raphaëlle Chaine a Marie-Paule Cani b,c Karan Singh d a LIRIS, University of Lyon b LJK, University of Grenoble c Inria, Grenoble d University of Toronto

2. Introduction • Design goals • Multi-dimensional nested structure • Sculpting system • Conclusion Contents

3. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • Goal: create, maintain, edit features during sculpting 1. Introduction

4. Related work: • Spatial deformations • Features have to be maintained externally • [Sederberg ’86, Wires, Singh ’98, von Funck ’06] • Professional sculpting applications emulate sharp features • [ZBrush, 3D Coat] 1. Introduction

5. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • Related work: • Object-aware deformations • Implicit – problems maintaining features • [Ferley 01] • Variational– topologically invariant features • [iWires, Gal 09] • Part-based modelers • complementary to free-form sculpting • [Meshmixer, Schmidt ’10] • Curve-network based modelers • shape from features • [FiberMesh, Nealen ’07] 1. Introduction

6. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • GOALS: • Concurrent deformation of objects and features. • Maintain or change topology of both. 1. Introduction 6

7. 2. Design goals. Pseudo-physical behavior

8. How to handle features in a discrete world? • Embed features in a discrete cell complex. • How it evolves under deformation? • Convergent updating scheme w. basic operations on cells. • DEFINITION • Multi-dimensional nested structure = • cell complex partitioning n-D space into n-D cells, bounded by (n-1)-D cells and so on to lower dimensions, with some boundaries marked as features. 3. Multi-dimensional nested structure

9. No features • Large deformations > cell complex update • Improve fidelity of the shape • Handle self-intersections - insertions 3. MDNS. General atomic operations on cells

10. 3. MDNS. Feature handling in updating scheme

11. Hierarchical processing • Bottom-up step:restore geometric quality • Top-down step: handle self-intersections 3. Multi-dimensional nested structure

12. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • Simplification: • Quasi-uniform mesh with features • [Freestyle ’11] • Operations (with features): • Edge split : cell division • Edge collapse : cell collapse • Edge flip : cell fusion + cell division • Vertex insertion : cell divisions + cell fusion • Edge flip : stability & quality • Vertex insertion : intersection 4. Sculpting system

13. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • Represent and deform shapes with nested features • Preserve or change properties of the deformed shape • Sculpting application adapted to creative workflow 5. Conclusion

14. Features on objects: • regions – appearance and function • curve networks – boundaries, creases • points – corners • Future work: • Sliders • Features glide on support • Non-orientable structures • Base structure for other methods • Features control the shape of support 5. Conclusion