Collision and Proximity Queries

1. Collision and Proximity Queries Dinesh Manocha Department of Computer Science University of North Carolina dm@cs.unc.edu

2. Collision Proximity Queries • A procedure to compute the spatial relation between objects.

3. d Proximity Queries Geometric reasoning of spatial relationships among objects (in a dynamic environment) Collision Detection Contact Points & Normals d Closest Points & Separation Distance Penetration Depth

4. Problem Domain Specifications • Model Representations • polyhedra (convex vs. non-convex vs. soups) • CSG, implicits, parametrics, point-clouds • Type of Queries • discrete vs. continuous query • distance vs. penetration computation • estimated time to collision • Simulation Environments • pairwise vs. n-body • static vs. dynamic • rigid vs. deformable

5. Applications • Robot motion planning • Simulation of (dis-)assembly tasks • Tolerance verification • Simulation-based design • Ergonomics analysis • Haptic rendering • Physics-based modeling and simulation

6. History Studied over 4 decades in • Computational Geometry • Robotics & Automation • Simulated Environments • Computer Animation • Physically-based Modeling

7. Earlier work: 1970s and 1980s • Algorithms for 2D & 3D intersection computation • Collision checking and avoidance

8. 1990’s: considerable momentum • Distance computation between convex polytopes (Gilbert et al. 1998; Lin & Canny’91) • Bounding volume hierarchies (sphere-trees, OBBTrees, k-DOP trees, Shelltrees) • N-body collision checking (sweep-and-prune, grid-based methods) • Collision systems for rigid models (I-Collide, RAPID, V-Collide, SOLID, QuickCD, PQP,….)

9. 1990’s: considerable momentum • Distance computation between convex polytopes (Gilbert et al. 1998; Lin & Canny’91) • Bounding volume hierarchies (sphere-trees, OBBTrees, k-DOP trees, Shelltrees) • N-body collision checking (sweep-and-prune, grid-based methods) • Collision systems for rigid models (I-Collide, RAPID, V-Collide, SOLID, QuickCD, PQP,….)

10. 1990’s: considerable momentum • Collision and contact computations for Physics-based simulation (Baraff’92; Lin’93; Mirtich’95)

11. 1990’s: considerable momentum • Collision checking for virtual environments (Cohen et al.’95)

12. 1990’s: considerable momentum • Haptic rendering (Gregory et al.’98; H-Collide)

13. Last 10-12 years • Novel algorithms • Discrete vs. continuous collision detection • Penetration depth computation • Deformable models • Self-collisions and breaking objects • Utilize the parallelism in multi-core CPUs and many-core GPUs • Development of Physics engines

14. Focus of this Course • Recent research on collision and proximity queries • Implementation in Game Physics libraries

15. Recent Research • Continuous collision detection and penetration depth queries (Young Kim) • Algorithms for deformable, breaking and volume meshes (Sungeui Yoon) • Acceleration using GPU parallelism (Dinesh Manocha)

16. Game Physics Simulation • Bullet Physics Library (Erwin Coumans) • NVIDIA PHYSX (Richard Tonge)