CS 448Z: Physically Based Animation and Sound

Course Description

Intermediate level, emphasizing physically based simulation techniques for computer animation and synchronized sound synthesis. Topics vary from year to year, but include the simulation of acoustic waves, and integrated approaches to visual and auditory simulation of rigid bodies, deformable solids, collision detection and contact resolution, fracture, fluids and gases, and virtual characters. Students will read and discuss papers, and complete open-ended projects with show-and-tell presentations.

Logistics

Location: Gates B3, Tu/Th 4:30–5:50 PM
Prerequisites: None required. Recommended: prior exposure to computer graphics and/or scientific computing.
Textbook: None; lecture notes and research papers assigned as readings will be posted here.
Communication: Slack
LMS: Canvas
Units: 3 or 4 (cross-listed; coursework is identical)
Exams: None

Course Structure

The course is organized around four projects of increasing scope: three focused assignments (HW1–HW3) followed by a self-directed final project. Each assignment period concludes with a show-and-tell session where students present their work. Lectures run throughout the quarter, covering the physics and algorithms behind animation sound synthesis.

Projects

HW1: Hello Animation Sound

20%

Weeks 1–2 · Show-and-tell: Thu Apr 9

Create a physics-based animation and add synchronized sound by hand.

HW2: Practical Modal Sound

20%

Weeks 3–4 · Show-and-tell: Thu Apr 23

Modal vibration and sound synthesis.

HW3: Making Noise

20%

Weeks 5–6 · Show-and-tell: Thu May 7

Acceleration noise, combustion, aeroacoustics, fracture, and related methods.

Final Project

40%

Weeks 7–10 · Presentations: Tue Jun 2

Self-directed investigation on a student-selected topic related to physically based animation and sound.

Topics

Topics are chosen from the following (and vary by year):

Acoustic waves and radiation
Sound propagation and auralization
Listening and head-related transfer functions (HRTFs)
Rigid-body dynamics and contact modeling
Modal vibration analysis and synthesis
Acoustic transfer for modal vibrations
Acceleration noise for rigid-body impacts
Fracture simulation and sound
Reduced-order dynamics and thin shell sound
Elastic rod dynamics and sound
Liquid and bubble acoustics
Fire and combustion sound
Turbulence and aeroacoustic sound
Cloth simulation and sound
Time-domain wave-based sound synthesis
Inverse-Foley animation
Machine learning for sound generation
Integrated animation and sound systems
Selected topics (based on student interest)

Demos

Interactive demos are hosted on GitHub Pages.

Acoustic Point Sources — Monopole, dipole, and Green's function radiation in 2D
Plane Wave Scattering by a Cylinder — Plane wave diffraction around a rigid cylinder
Modal Sound Explorer — Strike strings, bars, membranes, and plates
Bubble Sound Bank — Shape drips, rain, streams, and waterfalls
Acoustic Bubble Simulator — Sound of an air bubble oscillating underwater

Schedule

Materials will be posted throughout the quarter. Dates and topics may shift.

Date	Topic	Materials
Tue Mar 31	Introduction	Slides (PDF)
Thu Apr 2	Acoustic Waves and Radiation	Slides (PDF) References M. S. Howe. (2002). Theory of Vortex Sound. Cambridge Texts in Applied Mathematics (No. 33). Cambridge University Press. Chapter 1. Bridson, Fedkiw, and Muller-Fischer. 2006. Fluid Simulation: SIGGRAPH 2006 Course Notes. See Appendix A for vector calculus primer.
Tue Apr 7	Acoustic Waves and Radiation (cont.)
Thu Apr 9	HW1 Show-and-Tell
Thu Apr 9	Modal Vibration Analysis & Sound Synthesis	Slides (PDF) References A. A. Shabana. Theory of Vibration, Volume II: Discrete and Continuous Systems. Springer-Verlag, 1990. van den Doel and Pai. The Sounds of Physical Shapes. Presence, 7(4), 1998. O'Brien, Shen, and Gatchalian. Synthesizing Sounds from Rigid-Body Simulations. SCA 2002. Zheng and James. Toward High-Quality Modal Contact Sound. ACM Trans. Graph. (SIGGRAPH 2011). James et al. Physically Based Sound for Computer Animation and Virtual Environments, SIGGRAPH 2016 Course. Changxi Zheng. Modal Vibration Course Notes (PDF), SIGGRAPH 2016.
Tue Apr 14	Acceleration Noise for Rigid-Body Impacts	Forthcoming References Chadwick, Zheng, and James. Precomputed Acceleration Noise for Improved Rigid-Body Sound. ACM Trans. Graph. (SIGGRAPH 2012). (PDF — Table 1 typo fixed) Chadwick, Zheng, and James. Faster Acceleration Noise for Multibody Animations using Precomputed Soundbanks. SCA 2012.
Thu Apr 16	Collision Detection	Forthcoming
Thu Apr 23	HW2 Show-and-Tell
Tue Apr 28	Fire Sound	Forthcoming References Chadwick and James. Animating Fire with Sound. ACM Trans. Graph. (SIGGRAPH 2011).
Thu Apr 30	Liquid Sound	Forthcoming References Zheng and James. Harmonic Fluids. ACM Trans. Graph. (SIGGRAPH 2009). Langlois, Zheng, and James. Toward Animating Water with Complex Acoustic Bubbles. ACM Trans. Graph. (SIGGRAPH 2016).
Tue May 5	Aerodynamic Sound	Forthcoming References Dobashi, Yamamoto, and Nishita. Real-Time Rendering of Aerodynamic Sound Using Sound Textures Based on CFD. ACM Trans. Graph., 22(3), 2003. Howe. Theory of Vortex Sound. Cambridge University Press, 2002.
Thu May 7	HW3 Show-and-Tell
Tue May 12	Fracture Sound	Forthcoming References Zheng and James. Rigid-Body Fracture Sound with Precomputed Soundbanks. ACM Trans. Graph. (SIGGRAPH 2010).
Thu May 14	Thin Shells	Forthcoming References Chadwick, An, and James. Harmonic Shells: A Practical Nonlinear Sound Model for Near-Rigid Thin Shells. ACM Trans. Graph. (SIGGRAPH Asia 2009).
Tue May 19	Elastic Rods	Forthcoming References Schweickart, James, and Marschner. Animating Elastic Rods with Sound. ACM Trans. Graph. (SIGGRAPH 2017).
Thu May 21	Time-Domain Wave-Based Synthesis	Forthcoming References Wang, Qu, Langlois, and James. Toward Wave-based Sound Synthesis for Computer Animation. ACM Trans. Graph. (SIGGRAPH 2018).
Tue May 26	Inverse-Foley Animation & Control	Forthcoming References Langlois and James. Inverse-Foley Animation: Synchronizing Rigid-Body Motions to Sound. ACM Trans. Graph. (SIGGRAPH 2014).
Thu May 28	Selected Topics / Project Updates	Forthcoming
Tue Jun 2	Final Project Presentations

Grading

Component	Weight
HW1: Hello Animation Sound	20%
HW2: Practical Modal Sound	20%
HW3: Making Noise	20%
Final Project	40%

The course is cross-listed as 3 and 4 units; coursework is identical regardless of unit count. Show-and-tell participation is part of each project grade.

AI, Tools, and Collaboration Policy

You are encouraged to use AI and other tools freely, including for literature searches, research, API questions, code generation (e.g., Claude Code), and writing assistance. You are also welcome to use third-party animation tools, software libraries, and assets.

All third-party resources must be acknowledged. Just as you would cite a software library in a project README, any use of AI-assisted code or writing, third-party assets, or substantive help from collaborators should be credited in your project documentation. Failure to acknowledge these contributions is a form of plagiarism and may result in not receiving credit for the course.

Cite all AI-generated material and/or explain how you have drawn on AI-generated material in your work.

Your evaluation is holistic, based on your effort, creative exploration, participation in discussions, presentations of your work, and overall contributions to the course—not on whether you wrote every line of code by hand.

Be thoughtful about data and privacy. Review and follow the guidelines provided in Stanford IT's resource on Responsible AI at Stanford. When using a third-party, non-Stanford-approved AI tool such as a personal ChatGPT account, make sure to check the fine print terms before signing up. Avoid inputting information that should not be made public. This includes personal or confidential information of your own or that others share with you, as well as proprietary or copyrighted materials.

Be prepared to fact-check and critically evaluate all AI-generated information. Generative AI tools can provide false information (called “hallucinations”), perpetuate biases and/or stereotypes, or draw on copyrighted information without proper attribution, and such problematic information is often presented very convincingly. The materials these tools generate do not necessarily meet the standards of this course.

This policy operates within the broader framework of Stanford policies on generative AI use and academic integrity. If any conflict arises between this description and university-level policy, the university policy takes precedence.

Previous Offerings

Spring 2021