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We describe a multiresolution curve representation, based on wavelets, that conveniently supports a variety of operations: smoothing a curve; editing the overall form of a curve while preserving its details; and approximating a curve within any given error tolerance for scan conversion. We present methods to support continuous levels of smoothing as well as direct manipulation of an arbitrary portion of the curve; the control points, as well as the discrete nature of the underlying hierarchical representation, can be hidden from the user. The multiresolution representation requires no extra storage beyond that of the original control points, and the algorithms using the representation are both simple and fast.

We present a system for semi-automatic creation of bas-relief sculpture. As an artistic medium, relief spans the continuum between 2D drawing or painting and full 3D sculpture. Bas-relief (or low relief) presents the unique challenge of squeezing shapes into a nearly-flat surface while maintaining as much as possible the perception of the full 3D scene. Our solution to this problem adapts methods from the tone-mapping literature, which addresses the similar problem of squeezing a high dynamic range image into the (low) dynamic range available on typical display devices. However, the bas-relief medium imposes its own unique set of requirements, such as maintaining small, fixed-size depth discontinuities. Given a 3D model, camera, and a few parameters describing the relative attenuation of different frequencies in the shape, our system creates a relief that gives the illusion of the 3D shape from a given vantage point while conforming to a greatly compressed height.

Line drawings can convey shape using remarkably minimal visual content. Suggestive contours, which are lines drawn at certain types of view-dependent surface inflections, were proposed recently as a way of improving the effectiveness of computer-generated line drawings. This paper extends previous work on static suggestive contours to dynamic and real-time settings. We analyze movement of suggestive contours with respect to changes in viewpoint, and offer techniques for improving the quality of strokes rendered for a moving camera. We describe practical algorithms for rendering drawings with contours and suggestive contours at interactive rates. Finally, we discuss techniques for improving the visual appearance of suggestive contours, in both the static and dynamic cases.

Many individuals are creating instruction that will be used for online learning. This paper reviews four generic categories of instructional principles: Instructional Design (pedagogical issues), Subject Matter (content issues), Language (semantic and syntactic issues), and Presentation (physical issues), that should be used as guidelines when designing instructional materials. Nine current considerations for the context of online learning are drawn from the literature and experience and we show how each relates to these existing guidelines. We conclude the four generic categories of instructional principles apply equally to the design of instruction for the context of online learning and most issues that people talk about when designing online instruction are simply elaborations of these existing principles. A job aid is provided to help designers systematically consider essential principles when designing online instruction.

We present a novel method for generating performance-driven, "hand-drawn" animation in real-time. Given an annotated set of hand-drawn faces for various expressions, our algorithm performs multi-way morphs to generate real-time animation that mimics the expressions of a user. Our system consists of a vision-based tracking component and a rendering component. Together, they form an animation system that can be used in a variety of applications, including teleconferencing, multi-user virtual worlds, compressed instructional videos, and consumer-oriented animation kits.This paper describes our algorithms in detail and illustrates the potential for this work in a teleconferencing application. Experience with our implementation suggests that there are several advantages to our hand-drawn characters over other alternatives: (1) flexibility of animation style; (2) increased compression of expression information; and (3) masking of errors made by the face tracking system that are distracting in photorealistic animations.