HotMedia is a novel scalable solution for delivering interactive rich media over the Internet. It is a delivery-suitable file format that can contain heterogeneous compositions of media bit streams as well as meta-data that define the behavior, composition, and interaction semantics. This enables the creation of lightweight single-file representations of interactive, multiphase presentations involving multiple media-type content. The HotMedia client has a smart content algorithm that infers types from the incoming data stream and fetches the media renderer components, user-interface components, and hyper-linked action components, all just-in-time, resulting in progressive and contest driven enrichment of the user experience. Internet users get a simple initial experience with minimal latency followed by enrichment of this experience. HotMedia has an open and extensible architecture, which enables and encourages the inclusion of new media-types, user-interfaces, and hyper-linked actions. By separating media-rendering from action-performing, it lets all media handle the same actions. HotMedia can also track on the server-side, user interactions and user-experience associated parameters. In its simplest usage HotMedia requires no more than a regular web server for delivery and no client-side preinstallation.

Offsets, sweeps, and Minkowski operations (M-ops) are easy to define in the existential (representation-free) mathematics of point sets, but computing ‘values’ for offset, swept, and M-summed entities is thought to be difficult by many. This article argues that such computations may be easy if (1) they are cast in specific application contexts, and (2) relevant mathematical definitions are discretized and implemented directly. The argument is based on 10 years of research on a range of motional, process-modeling, and visualization problems that involved offsetting, sweeping, and M-ops; the solution paradigm common to all was direct approximation of mathematical definitions, using ray representations and parallel computation as primary media. This article presents no new results; it merely summarizes a body of well documented research that illustrates an approach to problem solving, whose primary tenets are: compute only what you need to solve the problem at hand, and do that as directly as possible.

Rapid advances in computing hardware (workstations, PCs), infrastructure (networks, cable, telephone), product development software (geometric modeling, process simulations, graphics), and business models (emerging economies, international currency exchange) have provided the raw material to support true globalization of product development. This globalization in turn raises a strong need for members of an enterprise (design, manufacturing maintenance, sales, management) to exchange product information in a concurrent manner and collaborate throughout the life cycle of families of products. We summarize some of the key issues in computer supported cooperative work (CSCW) related to product development, and then cover some of our ongoing work in collaborative visualization and modeling. On visualization, we cover the collaborative aspects of: (a) geometry based rendering (3DIX) and (b) image based rendering (PanoramIX), and on modeling: (c) solid modeling (procedural solids, shape control), (d) real time reverse engineering (3D reconstruction), and (e) product data management (PM).

We describe a method for reconstructing an unknown surface from a set of data points. The basic approach is to extract the surface as a polygon mesh from an α‐shape. Even though alpha shapes are generalized polytopes having complicated internal structures, we show that manifold surfaces, with or without boundaries, can be efficiently generated, and these surfaces completely describe the α‐shapes to the extent that they are visible from outside. Unlike the original α‐shapes, the polygonal surfaces can be easily simplified to yield compact models suitable for a variety of geometric modeling applications such as surface fitting.