Haptics and Virtual Reality M. Zareinejad 1 Lecture 9: Implicit surface Deformable Object
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
11
Haptics and Virtual Reality
M. Zareinejad
Lecture 9:
Implicit surface Deformable Object
Implicit surface
2
Implicit surface and gradient map
3
Implicit surface
4
5
6
7
Constrained by a Plane
8
Surface Tracking
9
Surface Tracking
10
Surface Tracking
11
12
Haptic interaction with deformable objects:◦ Overview.
◦ Mesh-based simulation of deformation: The Mass-Spring method. The ChainMail method. Continuum mechanics methods:
The Finite Element Method (FEM). The Boundary Element Method (BEM).
The Cellular Neural Network (CNN) method.
Outline
13
Deformable Object
14
Haptic interaction with deformable objects
15
Haptic interaction with deformable objects
16
Haptic interaction with deformable objects
Goals:◦ Speed.
30Hz for visual feedback. 500-1000 Hz for haptic feedback.
◦ Stability.◦ Physical accuracy.
critical for medical applications: surgical training, planning and outcome prediction.
Challenges:◦ Governing physical laws.◦ Material coupling, e.g., elastic tissue & fluid.◦ Inhomogeneities & anisotropies.◦ Non-linear deformations.◦ Geometry changes, e.g., cutting, suturing.
Haptic simulation of deformable objects
17
Soft Tissue properties
Relationship between stress and strain
Possible Models:
Linear elasticityNonlinear elasticityViscoelasticity
18
ViscoelasticityCreep and creep recovery Stress Relaxation
Kelvin Maxwell Zener
19
Mesh-based techniques:◦ Connectivity among object nodes.◦ Difficult to handle:
large deformations (fluid flow). connectivity changes (cuts, fractures).
◦ Example: Finite Element Method (FEM) models.
Meshless techniques:◦ No connectivity among object nodes.◦ Easy to handle:
fluid flows. cuts, fractures, etc.
◦ Example: Smoothed Particle Hydrodynamics (SPH) models, Method of Finite Spheres (Kim, De, Srinivasan ‘03).
Mesh vs. meshless simulation of deformation
20
Surface models of deformation:◦ Object represented by points on its boundary G.◦ Not good for incompressibility, bending.
Volumetric models of deformation:◦ Object represented by all points in W.
Mesh-based simulation of deformation
21
Object = mass nodes connected by a network of linear springs.
Force on node Pi:
Advantages:◦ Easy to implement.◦ Consistent with the data structures used for graphic rendering.◦ Suitable for static or dynamic simulations.
Mass-spring models of deformation
ji
jiijji
iNjiji PP
PPlPPkF 0
)(
22
Triangular mesh T2 mesh
Spring-mass-type meshes
23
24
Mass-spring models of deformation
Related Documents
![Introduction - clnchina.com.cnicon.clnchina.com.cn/pdf/Cisco_Unified_Communications...Dial Plan IP User & Device Provisioning Services IP Endpoints IP M M M M M M M M PSTN 9.911 9.[2-9]xxxxxx](https://static.cupdf.com/doc/110x72/5ae05e5f7f8b9ad66b8e0ce4/introduction-plan-ip-user-device-provisioning-services-ip-endpoints-ip-m-m-m-m.jpg)
