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- Mathieu Desbrun, Mark Meyer, Peter Schröder, Alan H. Barr
- SIGGRAPH
- 1999

In this paper, we develop methods to rapidly remove rough features from irregularly triangulated data intended to portray a smooth surface. The main task is to remove undesirable noise and uneven edges while retaining desirable geometric features. The problem arises mainly when creating high-fidelity computer graphics objects using imperfectly-measured data… (More)

This paper proposes a unified and consistent set of flexible tools to approximate important geometric attributes, including normal vectors and curvatures on arbitrary triangle meshes. We present a consistent derivation of these first and second order differential properties using averaging Voronoi cells and the mixed Finite-Element/Finite-Volume method, and… (More)

- Alan H. Barr
- SIGGRAPH
- 1984

New hierarchical solid modeling operations are developed, which simulate twisting, bending, tapering, or similar transformations of geometric objects. The chief result is that the normal vector of an arbitrarily deformed smooth surface can be calculated directly from the surface normal vector of the undeformed surface and a transformation matrix.… (More)

- Demetri Terzopoulos, John C. Platt, Alan H. Barr, Kurt W. Fleischer
- SIGGRAPH
- 1987

The theory of elasticity describes deformable materials such as rubber, cloth, paper, and flexible metals. We employ elasticity theory to construct differential equations that model the behavior of non-rigid curves, surfaces, and solids as a function of time. Elastically deformable models are active: they respond in a natural way to applied forces,… (More)

- Mathieu Desbrun, Peter Schröder, Alan H. Barr
- Graphics Interface
- 1999

In this paper, we propose a stable and efficient algorithm for animating mass-spring systems. An integration scheme derived from implicit integration allows us to obtain interactive realistic animation of any mass-spring network. We alleviate the need to solve a linear system through the use of a predictor-corrector approach: We first compute a rapid… (More)

- Gilles Debunne, Mathieu Desbrun, Marie-Paule Cani, Alan H. Barr
- SIGGRAPH
- 2001

This paper presents a robust, adaptive method for animating dynamic visco-elastic deformable objects that provides a guaranteed frame rate. Our approach uses a novel automatic <i>space and time adaptive</i> level of detail technique, in combination with a large-displacement (Green) strain tensor formulation. The body is partitioned in a non-nested… (More)

- Ronen Barzel, Alan H. Barr
- SIGGRAPH
- 1988

We present "dynamic constraints," a physically-based technique for constraint-based control of computer graphics models. Using dynamic constraints, we build objects by specifying geometric constraints; the models assemble themselves as the elements move to satisfy the constraints. The individual elements are rigid bodies which act in accordance with the… (More)

- Devendra Kalra, Alan H. Barr
- SIGGRAPH
- 1989

In this paper, we present a robust and mathematically sound ray-intersection algorithm for implicit surfaces. The algorithm is guaranteed to numerically find the nearest intersection of the surface with a ray, and is guaranteed not to miss fine features of the surface. It does not require fine tuning or human choice of interactive parameters. Instead, it… (More)

- John C. Platt, Alan H. Barr
- SIGGRAPH
- 1988

Simulating flexible models can create aesthetic motion for computer animation. Animators can control these motions through the use of <i>constraints</i> on the physical behavior of the models. This paper shows how to use mathematical constraint methods based on physics and on optimization theory to create controlled, realistic animation of physically-based… (More)

- David H. Laidlaw, Kurt W. Fleischer, Alan H. Barr
- IEEE Trans. Med. Imaging
- 1998

We present a new algorithm for identifying the distribution of different material types in volumetric datasets such as those produced with magnetic resonance imaging (MRI) or computed tomography (CT). Because we allow for mixtures of materials and treat voxels as regions, our technique reduces errors that other classification techniques can create along… (More)