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Explore the world of fracture modeling in computer graphics with this comprehensive survey covering physically-based and non-physically based methods, background on aging and weathering processes, simulation of cracks and fractures, and future work in the field.
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Fracture Modeling in ComputerGraphics A survey MIIACS Lien Muguercia Torres Advisors Dr. Gustavo A. Patow Dr. Carles Bosch
Why fracture? This thesis
Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work
Aging and weathering processes [Merillou08]
Aging and weathering processes • Specific aging model • Simulation • Global aging models • Aging as particles [Chen05] • Example based texture synthesis [Gu96; Matusik03]
Cracks and fractures in nature • Cracks: long and tiny • Fractures: desattachments • Mechanic classifications
Cracks and fractures in nature • Materials parameters • Stress • Strain • Yield strength • Fracture • Trans-granular • Inter-granular
Simulation fracture • Common steps over time • Compute internal forces • Determinate location and orientation • Modify the model
Physical models • Mass-spring system • Fast implementation/runtime • Poor visual results • FEM • Simulation precision • Computational cost • Mesh-less methods • Avoid mesh reconstruction • Bounding conditions
Time integration • Compute the state by extrapolating the previous one • Solving the implicit methods • by linearization • Compute the state at the end of the time step
Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work
Mass-spring models • Rigid bodies • Bodies as hybrid between rigid and deformable [Terzopoulos88; Norton91] • Model behavior of solid objects
Mass-spring models • Rigid bodies • Bodies as hybrid between rigid and deformable [Terzopoulos88; Norton91] • Model behavior of solid objects • Voxels • Connected with strong link values [Mazarak99] • Scaled/displaced in any directions [Martins01] • Has unique material properties
Mass-spring models • Tetrahedral elements • Each element equivalent six springs [Smith00] • Elements with same size cause undesirable artifacts [Hirota00] and lead with size adapted [Aoki04]
Finite element methods • Classic • Brittle/Ductile fracture animation [O’Brien99; O’Brien00; O’Brien02] • Simulation determinates cracks initiation and propagation analyzing stress value • High computation time
Finite element methods • Classic • Fluid dynamics model based using O’Brien approach [Yngue00] • An approach using heuristical stress [Iben09] • Replace as few tetrahedral as possible [Wicke10]
Finite element methods • Hybrid • Alternate rigid body and continuous model at the point of impact [Muller01; Molino04]
Finite element methods • Hybrid • Alternate rigid body and continuous model at the point of impact [Muller01; Molino04] • Bi-layered materials • Cracking induced by the material growth/shrinkage [Federl02] • Delaunay triangulation for mesh construction
Meshless methods • Based on particles/point-based representation • Compute spatial derivatives of displacement • Synthetize crack surfaces as triangle meshes [Muller04; Pauly05; Steinemann06]
Other methods • Crack propagation based on multi-layer Cellular Automata [Gobron01] • Crack propagation by systematic stress release of unstable cells
Physically-based methods • Which to choose? • Mass-spring, simple and fast / quality • FEM, accurate simulation / computational cost • Mesh-less, avoid mesh treatment / bounding restrictions • General problems • Computational time vs. quality
Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work
Image-based methods • Information extracted from images • Textured height field pattern [Wang03] • Reproducing input lines from images [Mould05] • Mapping and Bump mapping with real images [Hsien06] →
Procedural methods • Open, flexible and parameterizablesolution • Parallel strips to simulate bark generation [Lefebvre02] • Tools to control the patter by observation [Martinet04] • Mathematic algorithm to cracks in wax painting [Wyvill04]
Procedural methods • Connected voxel method as basis [Taubman04; Valette07] • Combining with mathematical equations for explosion or predefined crack path
Non-physically based methods • Advantages: • Intuitive • User control • Use criterion based… • In patterns extracted from images information • On the observation • Some simplified rules
Non-physically based methods • Problems • Visual quality could be improved • Suitable for interactivity application e.g. video games
Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work
Conclusions • Simulating fracture → a challenging task • Modeling the process: • Plausability → do physical simplifications • Accurate simulation → physical approach • Does not exist one ideal model for all kinds of applications
Problems • Quality simulation results small fragments/dust • Computation time required real-time to min/hours • Limited user control over animations Trade-off between then
Methods validation • Physically-based methods • Compare with experiments on real surfaces • Perception [Valette05; Ramanarayanan07] • Non-physically based methods • From a scientific point of view [Lu07] [Federl02]
Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work
Future work • Reproduce a specific pattern simulation • Example based techniques restricted to given pattern • An open problem • Combination of simulation + synthesis[Bosch11] • Extend → cracks and fractures No trivial
Challenge • Parameters extraction → images/geometry/other • Observation/Statistics • Find simulation parameters of a specific fracture state of the art study • Based on an existing simulation model
Inverse model process caracteristics • Urban environment Building materials Indirected causes Resistents No elastic
Our inverse model process • Not accurate model • Real time solution • Simulation image-guided → promess process