David R. Forsey

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<i>Refinement</i> is usually advocated as a means of gaining finer control over a spline curve or surface during editing. For curves, refinement is a local process. It permits the change of control vertices and subsequent editing of the detail in one region of the curve while leaving control vertices in other regions unaffected. For tensor-product surfaces,(More)
Details can be added to spline surfaces by applying displacement maps. However, the computational intensity of displacement mapping prevents its use for interactive design. In this paper we explore a form of simulated displacement that can be used for interactive design by providing a preview of true displacements at low computational cost. §Introduction(More)
This paper presents a method for automatically generating a hierarchical B-spline surface from an initial set of control points. Given an existing mesh of control points , a mesh with half the resolution , is constructed by simultaneously approximating the finer mesh while minimizing a smoothness constraint using weighted least squares. Curvature measures(More)
We consider the construction of spline features on spline surfaces. 1 The approach taken is a generalization of the hierarchical surface introduced in Forsey88]. Features are regarded as spline-deened vector displacement elds that are overlain on existing surfaces. No assumption is made that the overlays are derived from the base surface. They may be(More)
Over the course of several years, an informal poll by Dave Forsey of commercial animators revealed that the single most useful tool to add to a computer animation system would be a way to control the simple act of pressing one object into another. This ability would drastically increase the range and style of animations that could be created within a(More)
SPAM (Simulation Platform for Animating Motion) is a simulation software system designed to address synchronization issues pertaining to both animation and simulation. SPAM provides application programs with the manipulation, con guration, and synchronization tools needed when simulations are combined to create animations. It is designed to be used as the(More)
This paper describes a simple technique for evaluating the length of a parametric curve. The technique approximates sections of the curve to the arc of a circle using only sample points on the curve: no computation of derivatives or other properties is required. This method is almost as quick to implement and compute as chord-length summation but is much(More)
This paper presents Langwidere, a facial animation system. Langwidere is the basis for a flexible system capable of imitating a wide range of characteristics and actions, such as speech or expressing emotion. Langwidere integrates a hierarchical spline modeling system with simulated muscles based on local area surface deformation. The multi-level shape(More)