Truth in Motion: The Unprecedented Risks and Opportunities of Extended Reality Motion Data
Vivek Nair, Louis Rosenberg, James F. O'Brien, Dawn Song
IEEE S&P
Motion tracking “telemetry” data lies at the core of nearly all modern extended reality (XR) and metaverse experiences. While generally presumed innocuous, recent studies ... [more]
Berkeley Open Extended Reality Recordings 2023 (BOXRR-23): 4.7 Million Motion Capture Recordings from 105,000 XR Users
Vivek Nair, Wenbo Guo, Rui Wang, James F. O'Brien, Louis Rosenberg, Dawn Song
IEEE VR 2024
Extended reality (XR) devices such as the Meta Quest and Apple Vision Pro have seen a recent surge in attention, with motion tracking "telemetry" data lying at the core of nearly ... [more]
Unique Identification of 50,000+ Virtual Reality Users from Head and Hand Motion Data
Vivek Nair, Wenbo Guo, Justus Mattern, Rui Wang, James F. O'Brien, Louis Rosenberg, Dawn Song
USENIX Security 23
With the recent explosive growth of interest and investment in virtual reality (VR) and the “metaverse,” public attention has rightly shifted toward the unique security and ... [more]
Exploring the Unprecedented Privacy Risks of the Metaverse
Vivek Nair, Gonzalo Munilla Garrido, Dawn Song, James F. O'Brien
PoPETS 2023
Thirty study participants playtested an innocent-looking "escape room" game in virtual reality (VR). Behind the scenes, an adversarial program had accurately inferred over ... [more]
KBody: Balanced monocular whole-body estimation
Nikolaos Zioulis, James F. O'Brien
CVFAD 2023
KBody is a method for fitting a low-dimensional body model to an image. It follows a predict-and-optimize approach, relying on data-driven model estimates for the constraints ... [more]
KBody: Towards general, robust, and aligned monocular whole-body estimation
Nikolaos Zioulis, James F. O'Brien
RHOBIN 2023
KBody is a method for fitting a low-dimensional body model to an image. It follows a predict-and-optimize approach, relying on data-driven model estimates for the constraints ... [more]
Monocular Facial Performance Capture Via Deep Expression Matching
Stephen Bailey, Jérémy Riviere, Morten Mikkelsen, James F. O'Brien
SCA 2022
Facial performance capture is the process of automatically animating a digital face according to a captured performance of an actor. Recent developments in this area have ... [more]
This photograph has been altered: Testing the effectiveness of image forensic labeling on news image credibility
Cuihua Shen, Mona Kasra, James F. O'Brien
Misinformation Review
Despite the ubiquity of images and videos in online news environments, much of the existing research on misinformation and its correction is solely focused on textual misinformation ... [more]
Fast and Deep Facial Deformations
Stephen Bailey, Dalton Omens, Paul Dilorenzo, James F. O'Brien
SIGGRAPH 2020
Film-quality characters typically display highly complex and expressive facial deformation. The underlying rigs used to animate the deformations of a character’s face ... [more]
Fake images: The effects of source, intermediary, and digital media literacy on contextual assessment of imag credibility online
Cuihua Shen, Mona Kasra, Wenjing Pan, Grace A. Bassett, Yining Malloch, James F. O'Brien
New Media and Society
Fake or manipulated images propagated through the Web and social media have the capacity to deceive, emotionally distress, and influence public opinions and actions. Yet ... [more]
Fast and Deep Deformation Approximations
Stephen Bailey, Dave Otte, Paul Dilorenzo, James F. O'Brien
SIGGRAPH 2018
Character rigs are procedural systems that compute the shape of an animated character for a given pose. They can be highly complex and must account for bulges, wrinkles, and ... [more]
Approximate svBRDF Estimation From Mobile Phone Video
Rachel A. Albert, Dorian Yao Chan, Dan B Goldman, James F. O'Brien
EGSR 2018
We describe a new technique for obtaining a spatially varying BRDF (svBRDF) of a flat object using printed fiducial markers and a cell phone capable of continuous flash video ... [more]
Seeing Is Believing: How People Fail to Identify Fake Images on the Web
Mona Kasra, Cuihua Shen, James F. O'Brien
CHI 2018
The growing ease with which digital images can be convincingly manipulated and widely distributed on the Internet makes viewers increasingly susceptible to visual misinformation ... [more]
Simulation of Subseismic Joint and Fault Networks Using a Heuristic Mechanical Model
Paul Gillespie, Giulio Casini, Hayley Iben, James F. O'Brien
SSRD 2017
Flow simulations of fractured and faulted reservoirs require representation of subseismic structures about which subsurface data are limited. We describe a method for ... [more]
Seeing Is Believing: Do People Fail to Identify Fake Images on the Web?
Mona Kasra, Cuihua Shen, James F. O'Brien
AoIR 2016
Images have historically been perceived as photographic proof of the depicted events. However, the growing ease with which digital images can be convincingly manipulated ... [more]
Repurposing Hand Animation for Interactive Applications
Stephen Bailey, Martin Watt, James F. O'Brien
SCA 2016
In this paper we describe a method for automatically animating interactive characters based on an existing corpus of key-framed hand-animation. The method learns separate ... [more]
Interactive Detailed Cutting of Thin Sheets
Pierre-Luc Manteaux, Wei-Lun Sun, Francois Faure, Marie-Paule Cani, James F. O'Brien
MIG 2015
In this paper we propose a method for the interactive detailed cutting of deformable thin sheets. Our method builds on the ability of frame-based simulation to solve for ... [more]
View-Dependent Adaptive Cloth Simulation with Buckling Compensation
Woojong Koh, Rahul Narain, James F. O'Brien
TVCG 2015
This paper describes a method for view-dependent cloth simulation using dynamically adaptive mesh refinement and coarsening. Given a prescribed camera motion, the method ... [more]
Optimal Presentation of Imagery with Focus Cues on Multi-Plane Displays
Rahul Narain, Rachel A. Albert, Abdullah Bulbul, Gregory J. Ward, Marty Banks, James F. O'Brien
SIGGRAPH 2015
We present a technique for displaying three-dimensional imagery of general scenes with nearly correct focus cues on multi-plane displays. These displays present an additive ... [more]
Resampling Adaptive Cloth Simulations onto Fixed-Topology Meshes
George Brown, Armin Samii, James F. O'Brien, Rahul Narain
SCA 2015 Poster
We describe a method for converting an adaptively remeshed simulation of cloth into an animated mesh with fixed topology. The topology of the mesh may be specified by the ... [more]
Exposing Photo Manipulation from Shading and Shadows
Eric Kee, James F. O'Brien, Hany Farid
TOG 2014
We describe a method for detecting physical inconsistencies in lighting from the shading and shadows in an image. This method imposes a multitude of shading- and shadow-based ... [more]
Adaptive Tearing and Cracking of Thin Sheets
Tobias Pfaff, Rahul Narain, Juan Miguel de Joya, James F. O'Brien
SIGGRAPH 2014
This paper presents a method for adaptive fracture propagation in thin sheets. A high-quality triangle mesh is dynamically restructured to adaptively maintain detail ... [more]
Self-Refining Games using Player Analytics
Matt Stanton, Ben Humberston, Brandon Kase, James F. O'Brien, Kayvon Fatahalian, Adrien Treuille
SIGGRAPH 2014
Data-driven simulation demands good training data drawn from a vast space of possible simulations. While fully sampling these large spaces is infeasible, we observe that ... [more]
View-Dependent Adaptive Cloth Simulation
Woojong Koh, Rahul Narain, James F. O'Brien
SCA 2014
This paper describes a method for view-dependent cloth simulation using dynamically adaptive mesh refinement and coarsening. Given a prescribed camera motion, the method ... [more]
Can 3D Shape be Estimated from Focus Cues Alone?
Rachel A. Albert, Abdullah Bulbul, Rahul Narain, James F. O'Brien, Martin S. Banks
VSS 2014
Focus cues—blur and accommodation—have generally been regarded as very coarse, ordinal cues to depth. This assessment has been largely determined by the inability to display ... [more]
Correct blur and accommodation information is a reliable cue to depth ordering.
Marina Zannoli, Rachel A. Albert, Abdullah Bulbul, Rahul Narain, James F. O'Brien, Martin Banks
VSS 2014
Marshall et al. (1996) showed that blur could in principle also be used to determine depth ordering of two surfaces across an occlusion boundary from the correlation between ... [more]
The Perception of Surface Material from Disparity and Focus Cues
Martin Banks, Abdullah Bulbul, Rachel Albert, Rahul Narain, James F. O'Brien, Gregory Ward
VSS 2014
The visual properties of surfaces reveal many things including a floor's cleanliness and a car's age. These judgments of material are based on the spread of light reflected ... [more]
Fast Simulation of Mass-Spring Systems
Tiantian Liu, Adam Bargteil, James F. O'Brien, Ladislav Kavan
SIGGRAPH Asia 2013
We describe a scheme for time integration of mass-spring systems that makes use of a solver based on block coordinate descent. This scheme provides a fast solution for classical ... [more]
Exposing Photo Manipulation with Inconsistent Shadows
Eric Kee, James F. O'Brien, Hany Farid
TOG 2013
We describe a geometric technique to detect physically inconsistent arrangements of shadows in an image. This technique combines multiple constraints from cast and attached ... [more]
Folding and Crumpling Adaptive Sheets
Rahul Narain, Tobias Pfaff, James F. O'Brien
SIGGRAPH 2013
We present a technique for simulating plastic deformation in sheets of thin materials, such as crumpled paper, dented metal, and wrinkled cloth. Our simulation uses a framework ... [more]
Near-exhaustive Precomputation of Secondary Cloth Effects
Doyub Kim, Woojong Koh, Rahul Narain, Kayvon Fatahalian, Adrien Treuille, James F. O'Brien
SIGGRAPH 2013
The central argument against data-driven methods in computer graphics rests on the curse of dimensionality: it is intractable to precompute "everything" about a complex ... [more]
Simulating Liquids and Solid-Liquid Interactions with Lagrangian Meshes
Pascal Clausen, Martin Wicke, Jonathan Shewchuk, James F. O'Brien
TOG 2013
This paper describes a Lagrangian finite element method that simulates the behavior of liquids and solids in a unified framework. Local mesh improvement operations maintain ... [more]
Adaptive Anisotropic Remeshing for Cloth Simulation
Rahul Narain, Armin Samii, James F. O'Brien
SIGGRAPH Asia 2012
We present a technique for cloth simulation that dynamically refines and coarsens triangle meshes so that they automatically conform to the geometric and dynamic detail ... [more]
Updated Sparse Cholesky Factors for Corotational Elastodynamics
Florian Hecht, Yeon Jin Lee, Jonathan Shewchuk, James F. O'Brien
TOG 2012
We present warp-canceling corotation, a nonlinear finite element formulation for elastodynamic simulation that achieves fast performance by making only partial or ... [more]
Exposing Digital Forgeries in Ballistic Motion
Valentina Conotter, James F. O'Brien, Hany Farid
TIFS 2012
We describe a geometric technique to detect physically implausible trajectories of objects in video sequences. This technique explicitly models the three-dimensional ... [more]
Exposing Photo Manipulation with Inconsistent Reflections
James F. O'Brien, Hany Farid
TOG 2012
The advent of sophisticated photo editing software has made it increasingly easier to manipulate digital images. Often visual inspection cannot definitively distinguish ... [more]
Data-Driven Elastic Models for Cloth: Modeling and Measurement
Huamin Wang, Ravi Ramamoorthi, James F. O'Brien
SIGGRAPH 2011
Cloth often has complicated nonlinear, anisotropic elastic behavior due to its woven pattern and fiber properties. However, most current cloth simulation techniques simply ... [more]
Perceptually Based Tone Mapping for Low-Light Conditions
Adam Kirk, James F. O'Brien
SIGGRAPH 2011
In this paper we present a perceptually based algorithm for modeling the color shift that occurs for human viewers in low-light scenes. Known as the Purkinje effect, this ... [more]
Bringing Clothing into Desired Configurations with Limited Perception
Marco Cusumano-Towner, Arjun Singh, Stephen Miller, James F. O'Brien, Pieter Abbeel
ICRA 2011
We consider the problem of autonomously bringing an article of clothing into a desired configuration using a general-purpose two-armed robot. We propose a hidden Markov ... [more]
Modeling and Perception of Deformable One-Dimensional Objects
Shervin Javdani, Sameep Tandon, Jie Tang, James F. O'Brien, Pieter Abbeel
ICRA 2011
Recent advances in the modeling of deformable one-dimensional objects (DOOs) such as surgical suture, rope, and hair show significant promise for improving the simulation ... [more]
Multi-Resolution Isotropic Strain Limiting
Huamin Wang, James F. O'Brien, Ravi Ramamoorthi
SIGGRAPH Asia 2010
In this paper we describe a fast strain-limiting method that allows stiff, incompliant materials to be simulated efficiently. Unlike prior approaches, which act on springs ... [more]
Example-Based Wrinkle Synthesis for Clothing Animation
Huamin Wang, Florian Hecht, Ravi Ramamoorthi, James F. O'Brien
SIGGRAPH 2010
This paper describes a method for animating the appearance of clothing, such as pants or a shirt, that fits closely to a figure's body. Compared to flowing cloth, such as loose ... [more]
Dynamic Local Remeshing for Elastoplastic Simulation
Martin Wicke, Daniel Ritchie, Bryan Klingner, Sebastian Burke, Jonathan Shewchuk, James F. O'Brien
SIGGRAPH 2010
We propose a finite element simulation method that addresses the full range of material behavior, from purely elastic to highly plastic, for physical domains that are substantially ... [more]
Simulation of Needle Insertion and Tissue Deformation for Modeling Prostate Brachytherapy
Nuttapong Chentanez, Ron Alterovitz, Daniel Ritchie, Lita Cho, Kris Hauser, Ken Goldberg, Jonathan Shewchuk, James F. O'Brien
ABS 2010
Realistic modeling of needle insertion during brachytherapy can be used for training and in automated planning to reduce errors between intended and actual placement ... [more]
Using Blur to Affect Perceived Distance and Size
Robert (Robin) Held, Emily Cooper, James F. O'Brien, Marty Banks
TOG 2010
We present a probabilistic model of how viewers may use defocus blur in conjunction with other pictorial cues to estimate the absolute distances to objects in a scene. Our ... [more]
Generating Surface Crack Patterns
Hayley Iben, James F. O'Brien
Graphical Models
We present a method for generating surface crack patterns that appear in materials such as mud, ceramic glaze, and glass. To model these phenomena, we build upon existing physically ... [more]
Interactive Simulation of Surgical Needle Insertion and Steering
Nuttapong Chentanez, Ron Alterovitz, Daniel Ritchie, Lita Cho, Kris Hauser, Ken Goldberg, Jonathan Shewchuk, James F. O'Brien
SIGGRAPH 2009
We present algorithms for simulating and visualizing the insertion and steering of needles through deformable tissues for surgical training and planning. Needle insertion ... [more]
Real-Time Deformation and Fracture in a Game Environment
Eric G. Parker, James F. O'Brien
SCA 2009
This paper describes a simulation system that has been developed to model the deformation and fracture of solid objects in a real-time gaming context. Based around a corotational ... [more]
Refolding Planar Polygons
Hayley Iben, James F. O'Brien, Erik Demaine
DCG
This paper describes an algorithm for generating a guaranteed intersection-free interpolation sequence between any pair of compatible polygons. Our algorithm builds ... [more]
Making Big Things Look Small: Blur combined with other depth cues affects perceived size and distance
Robert (Robin) Held, Emily Cooper, James F. O'Brien, Marty Banks
VSS 2008
Blur is commonly considered a weak distance cue, but photographic techniques that manipulate blur cause significant and compelling changes in the perceived distance ... [more]
Liquid Simulation on Lattice-Based Tetrahedral Meshes
Nuttapong Chentanez, Bryan Feldman, François Labelle, James F. O'Brien, Jonathan Shewchuk
SCA 2007
This paper describes a simulation method for animating the behavior of incompressible liquids with complex free surfaces. The region occupied by the liquid is discretized ... [more]
A Method for Cartoon-Style Rendering of Liquid Animations
Ashley M. Eden, Adam Bargteil, Tolga Goktekin, Sara Beth Eisinger, James F. O'Brien
GI 2007
In this paper we present a visually compelling and informative cartoon rendering style for liquid animations. Our style is inspired by animations such as Futurama, The Little ... [more]
A semi-Lagrangian contouring method for fluid simulation
Adam Bargteil, Tolga Goktekin, James F. O'Brien, John A. Strain
ACM Trans. Graphics
In this paper we present a semi-Lagrangian surface tracking method for use with fluid simulations. Our method maintains an explicit polygonal mesh that defines the surface ... [more]
Optimization of HDR brachytherapy dose distributions using linear programming with penalty costs
Ron Alterovitz, Etienne Lessard, Jean Pouliot, I-Chow Joe Hsu, James F. O'Brien, Ken Goldberg
J. Medical Physics
Prostate cancer is increasingly treated with high-dose-rate (HDR) brachytherapy, a type of radiotherapy in which a radioactive source is guided through catheters temporarily ... [more]
A Texture Synthesis Method for Liquid Animations
Adam Bargteil, Funshing Sin, Jonathan E. Michaels, Tolga Goktekin, James F. O'Brien
SCA 2006
In this paper we present a method for synthesizing textures on animated liquid surfaces generated by a physically based fluid simulation system. Rather than advecting ... [more]
Generating Surface Crack Patterns
Hayley Iben, James F. O'Brien
SCA 2006
We present a method for generating surface crack patterns that appear in materials such as mud, ceramic glaze, and glass. To model these phenomena, we build upon existing physically ... [more]
Simultaneous Coupling of Fluids and Deformable Bodies
Nuttapong Chentanez, Tolga Goktekin, Bryan Feldman, James F. O'Brien
SCA 2006
This paper presents a method for simulating the two-way interaction between fluids and deformable solids. The fluids are simulated using an incompressible Eulerian formulation ... [more]
Fluid Animation with Dynamic Meshes
Bryan Klingner, Bryan Feldman, Nuttapong Chentanez, James F. O'Brien
SIGGRAPH 2006
This paper presents a method for animating fluid with unstructured tetrahedral meshes that change at each time step. Meshes that conform well to changing boundaries and ... [more]
A Texture Synthesis Method for Liquid Animations
Adam Bargteil, Funshing Sin, Jonathan Michaels, James F. O'Brien
SIGGRAPH 2006 Tech Sketch
In this sketch we present a method for synthesizing textures on animated liquid surfaces generated by a physically based fluid simulation system. Rather than advecting ... [more]
Simultaneous Coupling of Fluids and Deformable Bodies
Nuttapong Chentanez, Tolga Goktekin, Bryan Feldman, James F. O'Brien
SIGGRAPH 2006 Tech Sketch
We describe a method for simultaneous two-way coupling of fluid and deformable bodies. The interaction between a fluid and deformable body can create complex and interesting ... [more]
Refolding Planar Polygons
Hayley Iben, James F. O'Brien, Erik Demaine
SoCG 2006
This paper describes an algorithm for generating a guaranteed-intersection-free interpolation sequence between any pair of compatible polygons. Our algorithm builds ... [more]
Computational Studies of Human Motion: Tracking and Motion Synthesis
David Forsyth, Okan Arikan, Leslie Ikemoto, James F. O'Brien, Deva Ramanan
Foundations and Trends
We review methods for kinematic tracking of the human body in video. The review is part of a projected book that is intended to cross-fertilize ideas about motion representation ... [more]
Animating Gases with Hybrid Meshes
Bryan Feldman, James F. O'Brien, Bryan Klingner
SIGGRAPH 2005
This paper presents a method for animating gases on unstructured tetrahedral meshes to efficiently model the interaction of the fluids with irregularly shaped obstacles ... [more]
Fast and Detailed Approximate Global Illumination by Irradiance Decomposition
Okan Arikan, David A. Forsyth, James F. O'Brien
SIGGRAPH 2005
In this paper we present an approximate method for accelerated computation of the final gathering step in a global illumination algorithm. Our method operates by decomposing ... [more]
Fluids in Deforming Meshes
Bryan Feldman, James F. O'Brien, Bryan Klingner, Tolga Goktekin
SCA 2005
This paper describes a simple modification to an Eulerian fluid simulation that permits the underlying mesh to deform independent of the simulated fluid's motion. The modification ... [more]
Pushing People Around
Okan Arikan, David Forsyth, James F. O'Brien
SCA 2005
We present an algorithm for animating characters being pushed by an external source such as a user or a game environment. We start with a collection of motions of a real person ... [more]
A semi-Lagrangian contouring method for fluid simulation
Adam Bargteil, Tolga Goktekin, James F. O'Brien, John A. Strain
SIGGRAPH 2005 Tech Sketch
In this sketch we present a semi-Lagrangian surface tracking method for use with fluid simulations. Our method main- tains an explicit polygonal mesh that defines the surface ... [more]
Skeletal Parameter Estimation from Optical Motion Capture Data
Adam Kirk, James F. O'Brien, David Forsyth
CVPR 2005
In this paper we present an algorithm for automatically estimating a subject’s skeletal structure from optical mo- tion capture data. Our algorithm consists of a series ... [more]
A Method for Animating Viscoelastic Fluids
Tolga Goktekin, Adam Bargteil, James F. O'Brien
SIGGRAPH 2004
This paper describes a technique for animating the behavior of viscoelastic fluids, such as mucus, liquid soap, pudding, toothpaste, or clay, that exhibit a combination of both ... [more]
Skeletal Parameter Estimation from Optical Motion Capture Data
Adam Kirk, James F. O'Brien, David Forsyth
SIGGRAPH 2004 Tech Sketch
In this sketch we present an algorithm for automatically estimating a subject's skeletal structure from optical motion capture data without using any a priori skeletal ... [more]
Refolding Planar Polygons
Hayley Iben, James F. O'Brien, Erik Demaine
SIGGRAPH 2004 Tech Sketch
This sketch describes a guaranteed technique for generating intersection-free interpolation sequences between arbitrary, non-intersecting, planar polygons. The computational ... [more]
Interpolating and Approximating Implicit Surfaces from Polygon Soup
Chen Shen, James F. O'Brien, Jonathan Shewchuk
SIGGRAPH 2004
This paper describes a method for building interpolating or approximating implicit surfaces from polygonal data. The user can choose to generate a surface that exactly ... [more]
Radiance Caching and Local Geometry Correction
Okan Arikan, David A. Forsyth, James F. O'Brien
SIGGRAPH 2004 Tech Sketch
We present a final gather algorithm which splits the irradiance integral into two components. One component captures the incident radiance due to distant surfaces. This ... [more]
Spectral Surface Reconstruction from Noisy Point Clouds
Ravi Kolluri, Jonathan Shewchuk, James F. O'Brien
SGP 2004
We introduce a noise-resistant algorithm for reconstructing a watertight surface from point cloud data. It forms a Delaunay tetrahedralization, then uses a variant of ... [more]
An Energy-Driven Approach to Linkage Unfolding
Jason Cantarella, Erik Demaine, Hayley Iben, James F. O'Brien
SoCG 2004
We present a new algorithm for unfolding planar polygonal linkages without self-intersection based on following the gradient flow of a "repulsive" energy function. This ... [more]
Motion Synthesis from Anotations
Okan Arikan, David Forsyth, James F. O'Brien
SIGGRAPH 2003
This paper describes a framework that allows a user to synthesize human motion while retaining control of its qualitative properties. The user paints a timeline with annotations ... [more]
Animating Suspended Particle Explosions
Bryan Feldman, James F. O'Brien, Okan Arikan
SIGGRAPH 2003
This paper describes a method for animating suspended particle explosions. Rather than modeling the numerically troublesome, and largely invisible blast wave, the method ... [more]
Spectral Watertight Surface Reconstruction
Ravi Kolluri, Jonathan Shewchuk, James F. O'Brien
SIGGRAPH 2003 Tech Sketch
We use spectral partitioning to reconstruct a watertight surface from point cloud data. This method is particularly effective for noisy and undersampled point sets with ... [more]
Interactive Deformation Using Modal Analysis with Constraints
Kris Hauser, Chen Shen, James F. O'Brien
Graphics Interface 2003
Modal analysis provides a powerful tool for efficiently simulating the behavior of deformable objects. This paper shows how manipulation, collision, and other constraints ... [more]
An Energy-Driven Approach to Linkage Unfolding
Jason Cantarella, Erik Demaine, Hayley Iben, James F. O'Brien
DIMACS 2002
In this paper, we introduce a new energy-driven approach for straightening polygonal arcs and convexifying polygonal cycles without self-intersection based on following ... [more]
Modelling with Implicit Surfaces that Interpolate
Greg Turk, James F. O'Brien
TOG
We introduce new techniques for modelling with interpolating implicit surfaces. This form of implicit surface was first used for problems of surface reconstruction and ... [more]
Graphical Modeling and Animation of Ductile Fracture
James F. O'Brien, Adam Bargteil, Jessica Hodgins
SIGGRAPH 2002
In this paper, we describe a method for realistically animating ductile fracture in common solid materials such as plastics and metals. The effects that characterize ductile ... [more]
Synthesizing sounds from rigid-body simulations
James F. O'Brien, Chen Shen, Christine Gatchalian
SCA 2002
This paper describes a real-time technique for generating realistic and compelling sounds that correspond to the motions of rigid objects. By numerically precomputing ... [more]
Modal Analysis for Real-Time Viscoelastic Deformation
Chen Shen, Kris Hauser, Christine Gatchalian, James F. O'Brien
SIGGRAPH 2002 Tech Sketch
This technical sketch describes how a standard analysis technique known as modal decomposition can be used for real-time model- ing of viscoelastic deformation. While ... [more]
Modeling the Accumulation of Wind-Driven Snow
Bryan Feldman, James F. O'Brien
SIGGRAPH 2002 Tech Sketch
This technical sketch presents a method for modeling the appearance of snow drifts formed by the accumulation of wind-blown snow near buildings and other obstacles. Our ... [more]
Synthesizing Sounds from Physically Based Motion
James F. O'Brien, Perry R. Cook, Georg Essl
SIGGRAPH 2001
The goal of this work is to develop techniques for approximating sounds that are generated by the motions of solid objects. Our methods builds on previous work in the field ... [more]
Image Based Rendering and Illumination Using Spherical Mosaics
Chen Shen, Heung-Yeung Shum, James F. O'Brien
SIGGRAPH 2001 Tech Sketch
The work described here extends the concentric mosaic representation developed by Shum and He to spherical mosaics that allow the viewer greater freedom of movement. Additionally ... [more]
Implicit Surfaces that Interpolate
Greg Turk, GHuong Quynh Dinh, James F. O'Brien, Gary Yngve
Shape Modeling International 2001
Implicit surfaces are often created by summing a collection of radial basis functions. Recently, researchers have begun to create implicit surfaces that exactly interpolate ... [more]
Animating Fracture
James F. O'Brien, Jessica Hodgins
CACM
We have developed a simulation technique that uses non-linear finite element analysis and elastic fracture mechanics to compute physically plausible motion for three-dimensional ... [more]
Combining Active and Passive Simulations for Secondary Motion
James F. O'Brien, Victor Zordan, Jessica Hodgins
CG&A
Objects that move in response to the actions of a main character often make an important contribution to the visual richness of an animated scene. We use the term "secondary ... [more]
Animating Explosions
Gary D. Yngve, James F. O'Brien, Jessica K. Hodgins
SIGGRAPH 2000
In this paper, we introduce techniques for animating explosions and their effects. The primary effect of an explosion is a disturbance that causes a shock wave to propagate ... [more]
Automatic Joint Parameter Estimation from Magnetic Motion Capture Data
James F. O'Brien, Robert Bodenheimer, Gabriel Brostow, Jessica Hodgins
GI 2000
This paper describes a technique for using magnetic motion capture data to determine the joint parameters of an articulated hierarchy. This technique makes it possible ... [more]
Graphical Modeling and Animation of Brittle Fracture
James F. O'Brien, Jessica Hodgins
SIGRAPH 1999
In this paper, we augment existing techniques for simulating flexible objects to include models for crack initiation and propagation in three-dimensional volumes. By ... [more]
Shape Transformation Using Variational Implicit Functions
James F. O'Brien, Greg Turk
SIGGRAPH 1999
Traditionally, shape transformation using implicit functions is performed in two distinct steps: 1) creating two implicit functions, and 2) interpolating between these ... [more]
Animating Sand, Mud, and Snow
Robert Sumner, James F. O'Brien, Jessica Hodgins
CGF
Computer animations often lack the subtle environmental changes that should occur due to the actions of the characters. Squealing car tires usually leave no skid marks ... [more]
Perception of Human Motion with Different Geometric Models
Jessica Hodgins, James F. O'Brien, Jack Tumblin
TVCG 1998
Human figures have been animated using a variety of geometric models including stick figures, polygonal models, and NURBS-based models with muscles, flexible skin, or clothing ... [more]
Animating Sand, Mud, and Snow
Robert Sumner, James F. O'Brien, Jessica Hodgins
GI 98
Computer animations often lack the subtle environmental changes that should occur due to the actions of the char- acters. Squealing car tires usually leave no skid marks ... [more]
Combining Active and Passive Simulations for Secondary Motion
James F. O'Brien, Victor Zordan, Jessica Hodgins
SIGGRAPH 1997 Tech Sketch
The secondary motion of passive objects in the scene is essential for appealing and natural-looking animated characters, but because of the difficulty of controlling ... [more]
Do Geometric Models Affect Judgments of Human Motion?
Jessica Hodgins, James F. O'Brien, Jack Tumblin
GI 97
Human figures have been animated using a wide variety of geometric models including stick figures, polygonal models, and NURBS-based models with muscles, flexible skin ... [more]
Animating Human Athletics
Jessica Hodgins, Wayne Wooten, David Brogan, James F. O'Brien
SIGGRAPH 1995
This paper describes algorithms for the animation of men and women performing three dynamic athletic behaviors: running, bicycling, and vaulting. We animate these behaviors ... [more]
Dynamic Simulation of Splashing Fluids
James F. O'Brien, Jessica Hodgins
Computer Animation 95
In this paper we describe a method for modeling the dynamic behavior of splashing fluids. The model simulates the behavior of a fluid when objects impact or float on its surface ... [more]