assignment 6: beyond rigid body dynamics€¦ · assignment 6: beyond rigid body dynamics topic...

ASSIGNMENT 6: BEYOND RIGID BODY DYNAMICSTopic Selected by 16th March | Demo DUE: 6th April, 2016 | Submission 6th April, 2016

10/03/2016CS7057: REALTIME PHYSICS (2015-16) - JOHN DINGLIANA PRESENTED BY MICHAEL MANZKE

2 ADVANCED PHYSICSPOSSIBLE TOPICS FOR REMAINING WEEKS

Deformable Objects

Cloth

Hair

Soft-bodies

Fluid

Fracture / Destruction

Character Physics

Cartoon Physics / Faux Physics

Controllable Dynamics


3 OVERVIEW

The overall goal of this final assignment is for you to independently work on an implementation-study based on a Real-time Physics paper in published in a major conference or journal.

Presentation/deliverables should be targetted towards the class

Your task is to discuss and explain the paper so that others will be implement it based on your notes and your demo

Marks will go for clarity of the presentation

It is not essential to implement the whole paper

This major project is worth 40% of the module


4 ASSIGNMENT DETAILS

Individual Meetings to discuss your choice of topic/paper: March 14nd

You must decide before March 16th

What topic (i.e. paper)? What you hope to achieve in your implementation (brief work plan);

dependencies, resources

Demo due: Wednesday 6th April ~5-7 mins + Q&A. Open to the class (any format you wish – may use ppt)

Submission: Wednesday 6th April A report in the form of tutorial notes up to 4 pages (times 12 pt or equivalent) OR

equivalently detailed slide set OR equivalently detailed online tutorial All above should be written by you and including references to any third party

papers, code or tutorials used Link to You-tube video of the implementation Submit via Blackboard http://mymodule.tcd.ie


5 INCEPTION MEETING: MONDAY 14ND MARCH

Individual Meetings in Lloyd 0.01 (my office)Before this you should: Provisionally decide on a paper and read it Understand why this paper is important, what aspects you plan to

implement and what aspects will be challenging, require detailed explanation

13:00 BARBARA

13:20 YUANQI

13:40 JEVGENIJS

14:00 NAVNEETH

14:20 PATRICK

14:40 ANEESH

15:00 MANUELA

15:20 DANIEL

15:40

16:00

16:20

16:40


6 ASSESSMENT

Approximate Marking Scheme:

Technical Marks 70% : Depth/complexity of technical implementation How informative is the tutorial? Any non-trivial info offered that will help

others implement the paper? How much info beyond existing tutorials is provided? Usefulness of demo/deliverables at conveying the technical

contribution (including Visualisation, i.e. making the variables apparent) Qualitative marks submission elements: 30% Demo: quality of demo + response to Q&A Report: quality of writing, references, format, structure Video: quality of video (aesthetic, engaging, meaningful)


7 RIGID BODY ENGINE EXTENSIONS

You may choose an in-depth implementation of a more advanced rigid body paper beyond what has been implemented so far. Could be one of:

Complete implementation of Lin-Canny[Cohen95] or V-Clip[Mirtich’98]

Complete BVH scheme for collision handling including generation, update, traversal and intersection testing e.g. [Gottschalk 96]

Complete implementation of Timewarp [Mirtich’00]

Complete inclusion of an LCP Solver for simultaneous impulse response or implementation of resting contact or constraints resting contacts [Baraff94]

Other topics in Rigid Bodies. Please see guidelines for selecting a paper and discuss with me.

[Baraff94] Baraff, D. Fast contact force computation for non-penetrating rigid bodies. In ACM Siggraph 1994.[Cohen95] Cohen, J.D., Lin, M.C., Manocha, D., and Ponamgi. M.K., I-collide: An interactive and exact collision detection system for large-scaled environments. In Symposium on Interactive 3D Graphics. 1995[Gottschalk 96] Gottschalk et al. OBBTree: a hierarchical structure for rapid interference detection. Siggraph1996[Hubbard96] Hubbard, P.M. Approximating Polyherawith Spheres, for Time-Critical Collision Detection. ACM Trans. on Graphics, 1996.[Mirtich 98] B. Mirtich: “V-Clip: Fast and Robust Polyhedral Collision Detection”. ACM Trans. Graph. 17(3): 177-208 (1998)[Mirtich 00] B. Mirtich. 2000. “Timewarp rigid body simulation”. In Proceedings of SIGGRAPH '00 (2000)


8 BEYOND RIGID BODIES

Choose a real-time physics paper in a major publication (see next slide), and implement a small demo based on it (N.B. You are not required to implement the whole paper). E.g. Position based dynamics: M. Mueller, B. Heidelberger, M. Hennix, and J.

Ratcliff. Journal of Visual. Communications & Image Representations. 18, 2, 2007

Interactive Manipulation of Rigid Body Simulations: J. Popovic, S. M. Seitz, M. Erdmann, Z. Popovic, and A. Witkin. In SIGGRAPH 2000

Stable Fluids : Jos Stam. In SIGGRAPH 99. 1999 (More Recent Ref: GDC 03 talk by Stam)

Dynamic Simulation of Splashing Fluids, James O’Brien & Jessica Hodgins, Computer Animation ’95

Plausible Motion Simulation for Computer Graphics Animation, R. Barzel, J. Hughes and D. Wood. In EG Workshop on Computer Animation and Simulation, 1996

Real-time Deformation and Fracture in a Game Environment,. Parker, E., and Obrien, J.F. In Eurographics symposium on computer animation

You may find and use additional references related to these papers that help you to implement them


9 MAJOR PUBLICATIONS

You may select your own paper (suggestions in the following slides are merely to save you time) –

discuss with me to make sure it is feasible/appropriate: March 14th

and you MUST confirm a paper BEFORE 16th March

If selecting a paper, it should be published in a journal of conference in the following list:

Full physics paper from one of the following Annual Conferences: Siggraph, Siggraph Asia, Eurographics

Full physics paper from the following Workshops: Symposium on Interactive 3D Graphics and Games (I3D), Symposium on Computer Animation

(SCA, previously called Eurographics Workshop on Computer Animation and Simulation) Article from one of the following major journals (must be related to real-time physics): ACM Transactions on Graphics (TOG), Computer Graphics Forum (CGF), IEEE Computer

Graphics and Applications (CG&A), IEEE Transactions on Visualisation and Computer Graphics (TVCG)

Many older seminal papers are slightly easier, picking a paper older than 20 years old may score slightly less marks as a result. Picking a paper not from the above publications will also cost marks but you may use other papers to help implement your demo.


10 SOURCE OF PUBLICATIONS

Official Pages for top Journals (Accessible from within TCD):

ACM TOG, Siggraph, Siggraph Asia, I3D, SCA are available at: http://portal.acm.org

Eurographics and CGF papers are available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1467-8659

IEEE CG&A : http://www.computer.org/portal/web/csdl/magazines/cga

IEEE TVCG: http://www.computer.org/csdl/trans/tg/2014/index.html(Click on “IEEE Explore Subscribers”)

See this page for off-campus access http://www.tcd.ie/Library/using-library/off-campus.php


DETAILED SUGGESTIONS


12 DEFORMABLE OBJECTS

Many types

Solids (Soft objects) e.g. Cloth, Hair, rubber Fluids: gases and liquids Phenomena: Fracture, plasticicty,

elasticityMany solutions:

Particles, FEM, BEM, FFD More granularity required in modelsProblems:

Lack of rigid assumptions: more on-the-fly computation More complex equations of motion

[Miuller05] M. Müller, B. Heidelberger, M. Teschner, M. Gross, Meshless Deformations Based on Shape Matching, SIGGRAPH'05

Soft Bodies:


13 CLOTH SIMULATION

Amongst simplest deformable bodies (2D continuum). Can be simulated as matrix of springs (particle system)

Various challenges

Accurate collision detection: Thin object + Self Collisions

Sufficient resolution

Stability

Volume preservation

Havok cloth video © Havok

[Baraff98] Baraff and Witkin. Large steps in cloth simulation. SIGGRAPH 1998


14 FLUIDSDifficult in 3D

Lack of rest-state

Continuum model

Complex equations of motion: Navier stokes

Main approaches:

Particle based (SPH): lagrangian

Volume based (MAC): Eulerian

Dimension reduction: 2D / Shallow water equations

Muller et al. Particle-based fluid simulation for interactive applications. Siggraph 2003

Jos Stam. Stable Fluids. Siggraph 1999.


15 FRACTURE/DESTRUCTION

Accurate fracture requires FEM/continuum model

Complex and expensive computations

Most current real-time applications pre-process destruction effects

[Muller01] Muller et al. Real-time simulation of deformation and fracture of stiff materials. EurographicsWorkshop on Simulation and Computer Animation, 2001


16 CARTOON PHYSICS/FAUX PHYSICS

Stylised Animation

Simulate Disney Style Effects e.g. squash and Stretch

Enhance appeal, grab attention, provide cues

OPALACH, A., AND MADDOCK, S. 1994. Disney effects using implicit surfaces. In Proceedings of the Fifth Eurographics Workshop on Animation and Simulation, Eurographics.FALOUTSOS, P., VAN DE PANNE, M., TERZOPOLOUS,

D., Dynamic Free-Form Deformationsfor Animation Synthesis. IEEE TVCG Vol3(3) 1997.


17 DIRECTABLE DYNAMICS

Popvic Z., et al. Interactive manipulation of Rigid Body Simulations. Siggraph 2000.

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Stephen Chenney and D.A.Forsyth, "Sampling Plausible Solutions to Multi-Body Constraint Problems". SIGGRAPH 2000.

[Barzel96] Barzel, R., Hughes, J., Wood, D.N., Plausible Motion Simulation for

Computer Graphics Animation. In Eurographics Workshop on Computer

Animations and Simulation, 1996


18 CHARACTER PHYSICS

Various different scales:

Skin, hair, limb, face

Articulated object simulations (rag-doll)

Dynamics based characters

Blending motion capture and dynamics

Crowd dynamics

Lee, Y., Terzopolous, D., Waters, K., Realistic Modeling for Facial Animation. Siggraph 95

Ho, E., Komura, T., Tai, C-L., Spatial Relationship Preserving Character Motion Adaptation. Siggraph 2010

Adrien Treuille, Seth Cooper, and Zoran Popović. 2006. Continuum crowds. In ACM SIGGRAPH 2006.


19 HAIR SIMULATION

Individual strands: 1D continuum can be modelled with mass-springs. But several challenges in practice:

Typically many thousands of strands: Intercollisions + sticking/clustering

Self collisions, Inelastic behaviour

[Selle08] Selle, Andrew. Lentine, Michael. Fedkiw, Ronald. “A Mass Spring Model for Hair Simulation”. ACM Transactions on Graphics SIGGRAPH. 2008


20 OTHER REFERENCES

The following are some interesting practical references that aren’t from the top sources required for this assignment. But provide additional notes for implementing some of the listed seminal papers.

[Muller08] Real-time Physics Siggraph 2008 course notes in particular the section by Muller covers useful material related to soft objects, fluids and destruction.

http://www.matthiasmueller.info/realtimephysics/index.html


21

This assignment is worth 5% and you are expected to spend approx. 6-10 hours on this assignment. It will be in the form of an essay based on lectures and related readings from the second half of the semester – N.B. you write this in your own time (and there is no exam). Submission date: 14th April.

You are expected to answer two questions from a list that will be provided later in term. You are expected to write at least one page (~500 words) for each.

SAMPLE QUESTION: Rigid Bodies(a) Discuss at least four different types of bounding volume hierarchies used in collision detection. Discuss the advantages and disadvantages of each technique. Cite any relevant sources.(b) Explain what is meant by time critical collision detection in physically based animation and cite at least one example of a publication that employs this technique.

ASSIGNMENT 7 (PREVIEW)

(NOTE: THE ABOVE IS A SAMPLE QUESTION: you are not allowed to choose this option. Actual questions will be on upcoming topics from the final 5 weeks of term).


assignment 6: beyond rigid body dynamics€¦ · assignment 6: beyond rigid body dynamics topic...

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