The approximation tree is a hybrid, hierarchical data structure for real-time terrain visualization which represents both geometry data and texture data of a terrain in a hierarchical manner. This framework can integrate different multiresolution modeling techniques operating on different types of data sets such as TINs, regular grids, and non-regular grids. An approximation tree recursively aggregates terrain patches which reference geometry data and texture data. The rendering algorithm selects patches based on a geometric approximation error and a texture approximation error. Terrain shading and thematic texturing, which can be generated in a preprocessing step, improve the visual quality of level of detail models and eliminate the defects resulting from a Gouraud shaded geometric model since they do not depend on the current (probably reduced) geometry. The approximation tree can be implemented efficiently using object-oriented design principles. A case study for cartographic lands...

Introduction Electronic commerce is emerging as an important domain of integration and enhancement of various technologies and research efforts. A trend in e-commerce applications is to provide potential customers/visitors with the ability to preview and "test" products before they buy them. Using a 3-dimensional virtual representation of products is a step forward towards a persuasive preview. It is also very important for users to be able to view products in their own environment. These issues pose several technical and integration challenges. This work concerns the design and implementation of a system that allows the interactive design of a room, the definition of pieces of furniture and the placement of electrical and electronic appliances. The system works over the WWW offering web-users a tool for designing and visualizing their rooms. The users may define each object in the room, its size, position, and spatial relationships with the room or other objects. Certain i

This paper describes the design of a 3D rendering meta system which wraps the functionality of 3D rendering packages into a uniform, object-oriented framework. The homogeneous interface of the 3D rendering meta system serves as an easy-to-learn application programming interface to 3D rendering packages and allows us to exchange rendering packages without the need to recode an application. Our approach is based on a logical decomposition of the elements of 3D rendering into four major class categories: Shapes define geometric objects; attributes specify quality and visual appearance; controllers describe rendering techniques and rendering processes, and rendering engines evaluate shapes, attributes, and controllers. We have implemented our concepts in VRS, the Virtual Rendering System, as a portable C++ toolkit. VRS currently supports rendering packages such as OpenGL, PEX, XGL, Radiance, POV Ray, and RenderMan.

Figure 1: Tools for interactive editing: (a) interactive stretching and deformation of a car component; (b) 1D parameter texture revealing node relocation caused by relaxation. Virtual prototyping and numerical simulations are increasingly replacing real mock-ups and experiments in industrial product development. Many of these simulations, e.g. for the purpose of crash worthiness explorations, are based on Finite Element Analysis (FEA). In order to accelerate the development cycle, simulation engineers want to be able to modify their FE models without going back to the CAD department and without remeshing. Currently, there are no intuitive tools available that offer the possibility of modification and processing of FE components while maintaining the properties relevant to the simulation. In this paper we present interactive algorithms for intuitive, fast, and robust editing of FE models and appropriate visualization techniques to support engineers in understanding these models. New kinds of manipulators and feedback mechanisms enable easy manipulation of FE models. To ensure a good quality of the deformed mesh we use relaxation extended by algorithms preserving the features of the FE surface. For areas of large deformation we provide interactive methods to perform a remeshing in situ.

(c) future engineering workplace: autostereoscopic display and haptic input device. Virtual prototyping is increasingly replacing real mock-ups and experiments in industrial product development. Part of this process is the simulation of structural and functional properties, which is in many cases based on Finite Element Analysis (FEA). One prominent example from the automotive industry is the safety improvement resulting from crash worthiness simulations. A simulation model for this purpose usually consists of up to one million finite elements and is assembled from many parts which are individually meshed out of their CAD representation. In order to accelerate the development cycle, simulation engineers want to be able to modify their FE models without going back to the CAD department. Furthermore, valid CAD models might even not be available in preliminary design stages. However, in contrast to CAD, there is a lack of tools that offer the possibility of modification and processing of finite element components while maintaining the properties relevant to the simulation. In this application paper we present interactive algorithms for intuitive and fast editing of FE models and appropriate visualization techniques to support engineers in understanding these models. This includes new kinds of manipulators, feedback mechanisms and facilities for virtual reality and immersion at the workplace, e.g. autostereoscopic displays and haptic devices.