This paper discusses the problem of motion processing and proposes the use of a mathematical model, which describes a motion signal as a path with variable harmonic components. We show that this model is quite suited to representing a motion path as a periodic part with additional motion texture (noise). This provides a good mathematical formulation to the idea of "motion content". We also describe some mathematical tools that can be used with the model in order to construct different motion paths filters. As an application, we describe an algorithm to change automatically the time duration of a motion. We also point to interesting research directions on motion processing, using the model here introduced.

In this paper we introduce variable resolution 4‐k meshes, a powerful structure for the representation of geometric objects at multiple levels of detail. It combines most properties of other related descriptions with several advantages, such as more flexibility and greater expressive power. The main unique feature of the 4‐k mesh structure lies in its variable resolution capability, which is crucial for adaptive computation. We also give an overview of the different methods for constructing the 4‐k mesh representation, as well as the basic algorithms necessary to incorporate it in modeling and graphics applications.

Describes a technique to obtain a time dilation or contraction of an audio signal. Different computer graphics applications can take advantage of this technique. In real-time networked virtual reality applications, such as teleconferences or games, the audio might be transmitted independently from the rest of the data. These different signals arrive asynchronously and need to be somehow resynchronized on-the-fly. In animation, it can help to automatically fit and merge pre-recorded sound samples to special timed events. It also makes it easier to accomplish special effects, like lip-sync for dubbing or changing the voice of an animated character. Our technique tries to eliminate distortions by the replication of the original signal frequencies. Malvar wavelets are used to avoid clicking between segment transitions.

Direct interactive manipulation of 3D objects is very important in computer graphics. The user interface to deal with this problem poses a difficult problem because of the high number of degrees of freedom involved, associated with the loss of depth in the viewing projection. We introduce a new technique to specify displacement vectors in the three-dimensional space. The technique is built on top of the arcball interface introduced in (Shoemake, 1992). In fact, it constitutes a novel use of the arcball. We also discuss an implementation of the proposed technique in an interactive interface to specify displacement vectors in a widget for surface warping in 3D space.

This paper introduces a unified and general tesselation algorithm for parametric and implicit surfaces. The algorithm produces a hierarchial mesh that is adapted to the surface geometry and has a multiresolution and progressive structure. The representation can be exploited with advantages in several applications.

The recent developments in image-based rendering have enabled a representation of virtual environments based on a simulation of panoramas, which we call virtual panoramas. Current virtual panorama systems do not provide a natural and immersive interaction with the environment. We propose a new system that uses hardware and software components to provide a natural and immersive interaction with virtual panoramas. As part of the system we propose a specific representation for the interactions in a virtual panorama. This representation can be used as a basis for the design of a high-level language for the creation of such environments.

We develop a clustered dithering method that uses stochastic screening and is able to perform an adaptive variation of the cluster size.This makes it possible to achieve optimal rendition of gray shades while preserving image details.The algorithm is an improvement to the dithering with space filling curves method, published in [3].

This paper introduces a new digital halftoning technique that uses space filling curves to generate aperiodic patterns of clustered dots. This method allows the parameterization of the size of pixel clusters, which can vary in one pixel steps. The algorithm unifies, in this way, the dispersed and clustered-dot dithering techniques.