Hans J. W. Spoelder

Behavior-based neuro-fuzzy controller for mobile robot navigation

The paper discusses a neuro-fuzzy controller for sensor-based mobile robot navigation in indoor environments. The control system consists of a hierarchy of robot behaviors.

The distributed ASCI Supercomputer project

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project.

Visualization of time-dependent data with feature tracking and event detection

This paper presents an innovative method to analyze and visualize time-dependent evolution of features. The analysis and visualization of time-dependent data are complicated because of the immense number of data involved. However, if the scientists main interest is the evolution of certain features, it suffices to show the evolution of these features. The task of the visualization method is to extract the features from all frames, to determine the correspondences between features in successive frames, to detect significant events or stages in the evolution of the features, and, finally, to visualize the results. The method described here performs all these steps, and it is applied to a number of applications.

Virtual instrumentation and virtual environments

The objective of this work is to chart intriguing new possibilities and challenges resulting from the driving force and enabling factors of computing power and bandwidth that lie ahead of the instrumentation-and-measurement community. We do so by describing research and applications on the boundary between measurement, instrumentation, and virtual environments, and elucidate trends with some examples. We focus on three issues that are relevant to our view. The first issue deals with some of the essentials of instrument computer coupling. This part has a review-like character, and shows how the traditional hardware instrument was transformed into a network-accessible virtual instrument. The second issue deals with the changes in the programming paradigm and user interface of the virtual instrument. Here, we discuss how the notions of object and the advances of computer graphics transformed the programming model and the interaction of the user with it and its associated data. The third part deals with new developments, which we label virtual environments. It also deals with (sensor) data fusion in abstract environments. We show how this work can be seen as a logical fusion of the previous two developments.

Attribute-Based Feature Tracking

Visualization of time-dependent data is an enormous task because of the vast amount of data involved. However, most of the time the scientist is mainly interested in the evolution of certain features. Therefore, it suffices to show the evolution of these features. The task of the visualization system is to extract the features from all frames, to track the features, i.e. to determine the correspondences between features in successive frames, and finally to visualize the tracking results.

VIRPI: a high-level toolkit for interactive scientific visualization in virtual reality

Research areas that require interactive visualization of simulation data tend to dismiss virtual reality due to the lack of accessible tools for application specialists. This paper presents an integral toolkit for interactive visualization in virtual reality environments. The toolkit defines a framework to build applications that allow the user to interact with arbitrary simulation software and describe virtual measurement tools for the visualized data. The approach is illustrated with a case study in medical imaging.

Object recognition using pseudo-random color encoded structured light

This paper discusses a new structured light technique using multi-valued pseudo-random color encoded grid patterns. This encoding completely solves the point identification problem allowing for an absolute identification of both the line- and column-index of any individual grid node projected on a surface. The use of multi-valued sequences instead of binary sequences has the notable advantage of a more compact encoding which eventually leads to higher measurement precision.

Griz : experience with remote visualization over an optical grid

This paper describes the experiments of remote rendering over an intercontinental optical network during the iGrid2002 conference in Amsterdam from September 23 to 26. A rendering cluster in Chicago was used to generate images which were displayed in real-time on a 4-tile visualization setup in Amsterdam. On average, one gigabit per second (1 Gbps) was consumed to enable remote visualization, at interactive frame rate, with a 1600 × 1200 pixels configuration.

The Polder Computing Environment: a system for interactive distributed simulation

The paper provides an overview of an experimental, Grid‐like computing environment, Polder, and its components. Polder offers high‐performance computing and interactive simulation facilities to computational science. It was successfully implemented on a wide‐area cluster system, the Distributed ASCI Supercomputer. An important issue is an efficient management of resources, in particular multi‐level scheduling and migration of tasks that use PVM or sockets. The system can be applied to interactive simulation, where a cluster is used for high‐performance computations, while a dedicated immersive interactive environment (CAVE) offers visualization and user interaction. Design considerations for the construction of dynamic exploration environments using such a system are discussed, in particular the use of intelligent agents for coordination. A case study of simulatedabdominal vascular reconstruction is subsequently presented: the results of computed tomography or magnetic resonance imaging of a patient are displayed in CAVE, and a surgeon can evaluate the possible treatments by performing the surgeries virtually and analysing the resulting blood flow which is simulated using the lattice‐Boltzmann method. Copyright

CAVEStudy: an infrastructure for computational steering in virtual reality environments

We present the CAVEStudy system that enables scientists to interactively steer a simulation from a virtual reality (VR) environment. No modification to the source code is necessary. CAVEStudy allows interactive and immersive analysis of a simulation running on a remote computer. Using a high-level description of the simulation, the system generates the communication layer (based on CAVERN-Soft) needed to control the execution and to gather data at runtime. We describe three case-studies implemented with CAVEStudy: soccer simulation, diode laser simulation and molecular dynamics.