Jakob T. Valvoda

Low arousal modulates visuospatial attention in three-dimensional virtual space

Clinical, experimental, and functional imaging studies suggest overlapping neuronal networks and functional interactions of alertness and visuospatial attention within the right hemisphere of the brain. To examine the interaction of arousal and visuospatial attention in peripersonal and extrapersonal virtual space, we tested 20 healthy male adults during 24 hr of sleep deprivation at four points during the night (9 p.m., 1 a.m., 5 a.m., and 9 a.m.). The main finding concerning covert orienting in a virtual environment is a highly significant slowing of reorientation toward the left visual hemifield in extrapersonal space due to decreased arousal. The results provide additional evidence for the proposed anatomical and functional overlap of the two attentional systems and indicate a modulation of visuospatial attention by the level of arousal in extrapersonal space.

Subject-Based Regional Anaesthesia Simulator Combining Image Processing and Virtual Reality

In this paper, a novel virtual reality-based simulator for regional anaesthesia is presented. Individual datasets of patients with nerve cords are created from medical scans with the help of advanced segmentation and registration algorithms. Techniques for interaction and immersive visualization are utilized by the simulator to improve training of medical residents.

Comprehensive Architecture for Simulation of the Human Body Based on Functional Anatomy

In this paper we propose a structured approach for the simulation of the human body which is comprehensive and extendable. Our architecture resembles the human organism as defined by the systematic and functional anatomy to integrate a broad range of simulation algorithms. To share common data and to create interlinks between algorithms without modifying the algorithms themselves we introduce abstract control entities that mimic the basic setup of physiological systems. We utilize the model-view-controller pattern to establish a separation of algorithms and data. The structure was designed for the purpose of interactive simulation of the human body in virtual environments.

High ecological validity and accurate stimulus control in VR-based psychological experiments

Virtual Reality (VR) has become a useful tool in psychological therapy, rehabilitation, and basic research. It provides the therapist or scientist with high ecological validity and complete control over multimodal stimuli and the virtual environment. To build lifelike virtual environments, commercial software or game engines are often used. On the other hand, many psychological experiments require an accurate timing of presented stimuli and user reactions, which is not easily obtained by modern hard- and software systems. In this work, we present a VR software for psychological experiments which combines modern computer graphics and Virtual Reality techniques with accurate stimulus and event control. We describe the system features and possibilities for VRbased experiment generation and propose approaches for precise stimulus and event timing. These approaches are evaluated for achievable accuracy in stimulus control and performance monitoring within typical virtual environments.

Interactive Biomechanical Modeling and Simulation of Realistic Human Musculature in Virtual Environments

We present an approach to interactive modeling, biomechanical simulation and realistic visualization of human musculature. Our aim is to facilitate the use of these techniques in virtual environments; therefore special attention has been paid to the optimization of real-time approaches yielding results with a high degree of realism. Our system allows for immersive modeling of musculature and a real-time simulation of muscle forces based on biomechanical models.

A Virtual Reality-Based Framework for Experiments on Perception of Manual Gestures

This work contributes an integrated and flexible approach to sign language processing in virtual environments that allows for interactive experimental evaluations with high ecological validity. Initial steps deal with real-time tracking and processing of manual gestures. Motion data is stereoscopically rendered in immersive virtual environments with varying spatial and representational configurations. Besides flexibility, the most important aspect is the seamless integration within a VR-based neuropsychological experiment software. Ongoing studies facilitated with this system contribute to the understanding of the cognition of sign language. The system is beneficial for experimenters because of the controlled and immersive three-dimensional environment enabling experiments with visual depth perception that can not be achieved with video presentations.

Ein VR-basiertes rhinochirurgisches Softwaresystem für die Analyse der menschlichen Naseninnenströmung

Storungen der Nasenatmung stellen ein haufiges Krankheitsbild in der Rhinologie dar. Um die Behandlung zu optimieren und die Stromungsvorgange innerhalb der Nase besser zu verstehen, wird ein Softwaresystem entwickelt, welches die interaktive Analyse der Luftstromung in der Nasenhaupthohle in immersiven virtuellen Umgebungen erlaubt. Das System integriert Navigations-, Visualisierungs- und Annotationswerkzeuge, um die interdisziplinare Kommunikation zu fordern.