Concept and Workflow for 3D Visualization of Multifaceted Meteorological Data

The analysis of heterogeneous, complex data sets has become important in many scientific domains. With the help of scientific visualization, researchers can be supported in exploring their research results. One domain, where researchers have to deal with spatio-temporal data from different sources including simulation, observation and time-independent data, is meteorology. In this thesis, a concept and workflow for the 3D visualization of meteorological data was developed in cooperation with domain experts. Three case studies have been conducted based on the developed concept. In addition, the concept has been enhanced based on the experiences gained from the case studies. In contrast to existing all-in-one software applications, the proposed workflow employs a combination of existing software applications and their extensions to make a variety of already implemented visualization algorithms available. The workflow provides methods for data integration and for abstraction of the data as well as for generating representations of the variables of interest. Solutions for visualizing sets of variables, comparing results of multiple simulation runs and results of simulations based on different models are presented. The concept includes the presentation of the visualization scenes in virtual reality environments for a more comprehensible display of multifaceted data. To enable the user to navigate within the scenes, some interaction functionality was provided to control time, camera, and display of objects. The proposed methods have been selected with respect to the requirements defined in cooperation with the domain experts and have been verified with user tests. The developed visualization methods are used to analyze and present recent research results as well as for educational purposes. As the proposed approach uses generally applicable concepts, it can also be applied for the analysis of scientific data from other disciplines.In nahezu allen Wissenschaftsdisziplinen steigt der Umfang erhobener Daten. Diese sind oftmals heterogen und besitzen eine komplexe Struktur, was ihre Analyse zu einer Herausforderung macht. Die wissenschaftliche Visualisierung bietet hier Möglichkeiten, Wissenschaftler bei der Untersuchung ihrer Forschungsergebnisse zu unterstützen. Eine der Disziplinen, in denen räumlich-zeitliche Daten aus verschiedenen Quellen inklusive Simulations- und Observationsdaten eine Rolle spielen, ist die Meteorologie. In dieser Arbeit wurde in Zusammenarbeit mit Experten der Meteorologie ein Konzept und ein Workflow für die 3D-Visualisierung meteorologischer Daten entwickelt. Dabei wurden drei Fallstudien erarbeitet, die zum einen auf dem erstellten Konzept beruhen und zum anderen durch die während der Fallstudie gesammelten Erfahrungen das Konzept erweiterten. Der Workflow besteht aus einer Kombination existierender Software sowie Erweiterungen dieser. Damit wurden Funktionen zur Verfügung gestellt, die bei anderen Lösungsansätzen in diesem Bereich, die oft nur eine geringere Anzahl an Funktionalität bieten, nicht zur Verfügung stehen. Der Workflow beinhaltet Methoden zur Datenintegration sowie für die Abstraktion und Darstellung der Daten. Es wurden Lösungen für die Visualisierung einer Vielzahl an Variablen sowie zur vergleichenden Darstellung verschiedener Simulationsläufe und Simulationen verschiedener Modelle präsentiert. Die generierten Visualisierungsszenen wurden mit Hilfe von 3D-Geräten, beispielsweise eine Virtual-Reality-Umgebung, dargestellt. Die stereoskopische Projektion bietet dabei die Möglichkeit, diese komplexen Daten mit verbessertem räumlichem Eindruck darzustellen. Um dem Nutzer eine umfassende Analyse der Daten zu ermöglichen, wurden eine Reihe von Funktionen zur Interaktion zur Verfügung gestellt, um beispielsweise Zeit, Kamera und die Anzeige von 3D-Objekten zu steuern. Das Konzept und der Workflow wurden entsprechend der Anforderungen entwickelt, die zusammen mit Fachexperten definiert wurden. Des Weiteren wurden die Anwendungen in verschiedenen Entwicklungsstadien durch Nutzer getestet und deren Feedback in die Entwicklung einbezogen. Die Ergebnisse der Fallstudien wurden von den Wissenschaftlern benutzt, um ihre Daten zu analysieren, sowie diese zu präsentieren und in der Lehre einzusetzen. Da der vorgeschlagene Workflow allgemein anwendbare Konzepte beinhaltet, kann dieser auch für die Analyse wissenschaftlicher Daten anderer Disziplinen verwendet werden

Modeling Three-Dimensional Interaction Tasks for Desktop Virtual Reality

A virtual environment is an interactive, head-referenced computer display that gives a user the illusion of presence in real or imaginary worlds. Two most significant differences between a virtual environment and a more traditional interactive 3D computer graphics system are the extent of the user's sense of presence and the level of user participation that can be obtained in the virtual environment. Over the years, advances in computer display hardware and software have substantially progressed the realism of computer-generated images, which dramatically enhanced user’s sense of presence in virtual environments. Unfortunately, such progress of user’s interaction with a virtual environment has not been observed. The scope of the thesis lies in the study of human-computer interaction that occurs in a desktop virtual environment. The objective is to develop/verify 3D interaction models that can be used to quantitatively describe users’ performance for 3D pointing, steering and object pursuit tasks and through the analysis of the interaction models and experimental results to gain a better understanding of users’ movements in the virtual environment. The approach applied throughout the thesis is a modeling methodology that is composed of three procedures, including identifying the variables involved for modeling a 3D interaction task, formulating and verifying the interaction model through user studies and statistical analysis, and applying the model to the evaluation of interaction techniques and input devices and gaining an insight into users’ movements in the virtual environment. In the study of 3D pointing tasks, a two-component model is used to break the tasks into a ballistic phase and a correction phase, and comparison is made between the real-world and virtual-world tasks in each phase. The results indicate that temporal differences arise in both phases, but the difference is significantly greater in the correction phase. This finding inspires us to design a methodology with two-component model and Fitts’ law, which decomposes a pointing task into the ballistic and correction phase and decreases the index of the difficulty of the task during the correction phase. The methodology allows for the development and evaluation of interaction techniques for 3D pointing tasks. For 3D steering tasks, the steering law, which was proposed to model 2D steering tasks, is adapted to 3D tasks by introducing three additional variables, i.e., path curvature, orientation and haptic feedback. The new model suggests that a 3D ball-and-tunnel steering movement consists of a series of small and jerky sub-movements that are similar to the ballistic/correction movements observed in the pointing movements. An interaction model is originally proposed and empirically verified for 3D object pursuit tasks, making use of Stevens’ power law. The results indicate that the power law can be used to model all three common interaction tasks, which may serve as a general law for modeling interaction tasks, and also provides a way to quantitatively compare the tasks

Modeling object pursuit for desktop virtual reality

Models of interaction tasks are quantitative descriptions of relationships between human temporal performance and the spatial characteristics of the interactive tasks. Examples include Fitts' law for modeling the pointing task and Accot and Zhai's steering law for the path steering task. Interaction models can be used as guidelines to design efficient user interfaces and quantitatively evaluate interaction techniques and input devices. In this paper, we introduce and experimentally verify an interaction model for a 3D object-pursuit interaction task. Object pursuit requires that a user continuously tracks an object that moves with constant velocities in a desktop virtual environment. For modeling purposes, we divide the total object-pursuit movement into a tracking phase and a correction phase. Following a two-step modeling methodology that is originally proposed in this paper, the time for the correction phase is modeled as a function of path length, path curvature, target width, and target velocity. The object-pursuit model can be used to quantitatively evaluate the efficiency of user interfaces that involve 3D interaction with moving objects