Interactive blood damage analysis for ventricular assist devices.

Ventricular Assist Devices (VADs) support the heart in its vital task of maintaining circulation in the human body when the heart alone is not able to maintain a sufficient flow rate due to illness or degenerative diseases. However, the engineering of these devices is a highly demanding task. Advanced modeling methods and computer simulations allow the investigation of the fluid flow inside such a device and in particular of potential blood damage. In this paper we present a set of visualization methods which have been designed to specifically support the analysis of a tensor-based blood damage prediction model. This model is based on the tracing of particles through the VAD, for each of which the cumulative blood damage can be computed. The model's tensor output approximates a single blood cell's deformation in the flow field. The tensor and derived scalar data are subsequently visualized using techniques based on icons, particle visualization, and function plotting. All these techniques are accessible through a Virtual Reality-based user interface, which features not only stereoscopic rendering but also natural interaction with the complex three-dimensional data. To illustrate the effectiveness of these visualization methods, we present the results of an analysis session that was performed by domain experts for a specific data set for the MicroMed DeBakey VAD.

Comparative visualization of human nasal airflows.

The use of computational fluid dynamics allows to simulate a large number of different variations of a general flow phenomenon in a reasonable amount of time. This lays the foundation for large scale comparative studies. However, in order to be able to compare the simulation results effectively, advanced comparison methods are needed. In this paper we describe a set of techniques for the comparison of flow simulation results. All methods are integrated in a virtual reality based prototype and facilitate the interactive exploration of the data domain. As a specific application example the described techniques are used to compare different human nasal cavity flows to each other.

Employing graphics hardware for an interactive exploration of the airflow in the human nasal cavity.

This paper presents an interactive method for the intuitive exploration of airflow within the human nose. Employing the computational power of modern graphics hardware allows for computing the movement of large numbers of particles through the flow domain. By using tetrahedral grids, we preserve the precision of the numerical flow simulation even for irregular flow domains. For rendering, we employ billboard-based visualization methods, which result in a high visual quality at little computational cost and highly interactive frame rates.

Reaction-time measurement and real-time data acquisition for neuroscientific experiments in virtual environments.

This paper describes an approach to neuroscientific reaction-time experiments and resulting methods for data processing under real-time constraints in virtual environments (VE). Immersive VEs produce huge amounts of data, which has to be processed in real-time to meet the interactivity requirement of VE. Furthermore, data is needed often with a timing resolution and even more crucial with an accuracy in the range of milliseconds. Unfortunately recent operating systems do not in general guarantee timing precision in this range. For these purposes we have researched possibilities for reaction-time measurement and real-time data acquisition. Our system enables neuroscientists to perform reaction-time experiments in platform-independent virtual environments.

NeuroVRAC--a comprehensive approach to virtual reality-based neurological assessment and treatment systems.

We describe a comprehensive software-oriented approach to virtual reality-based neuroscientific systems in order to establish an easy to use framework for neuroscientific assessment and treatment. We have defined a process model and implemented the NeuroVRAC authoring tool for design and execution of experiments in virtual environments. Our system enables the modeling of virtual world objects and the definition of events, which are used to control the experimental process. We have included the virtual test person concept to enhance the sense of presence during the execution of virtual reality-based neuroscientific experiments.