Interactive Exploration (interactive + exploration)

Distribution by Scientific Domains

Selected Abstracts

An Exploratory Technique for Coherent Visualization of Time-varying Volume Data

A. Tikhonova
Abstract The selection of an appropriate global transfer function is essential for visualizing time-varying simulation data. This is especially challenging when the global data range is not known in advance, as is often the case in remote and in-situ visualization settings. Since the data range may vary dramatically as the simulation progresses, volume rendering using local transfer functions may not be coherent for all time steps. We present an exploratory technique that enables coherent classification of time-varying volume data. Unlike previous approaches, which require pre-processing of all time steps, our approach lets the user explore the transfer function space without accessing the original 3D data. This is useful for interactive visualization, and absolutely essential for in-situ visualization, where the entire simulation data range is not known in advance. Our approach generates a compact representation of each time step at rendering time in the form of ray attenuation functions, which are used for subsequent operations on the opacity and color mappings. The presented approach offers interactive exploration of time-varying simulation data that alleviates the cost associated with reloading and caching large data sets. [source]

DTI in Context: Illustrating Brain Fiber Tracts In Situ

Pjotr Svetachov
Abstract We present an interactive illustrative visualization method inspired by traditional pen-and-ink illustration styles. Specifically, we explore how to provide context around DTI fiber tracts in the form of surfaces of the brain, the skull, or other objects such as tumors. These contextual surfaces are derived from either segmentation data or generated using interactive iso-surface extraction and are rendered with a flexible, slice-based hatching technique, controlled with ambient occlusion. This technique allows us to produce a consistent and frame-coherent appearance with precise control over the lines. In addition, we provide context through cutting planes onto which we render gray matter with stippling. Together, our methods not only facilitate the interactive exploration and illustration of brain fibers within their anatomical context but also allow us to produce high-quality images for print reproduction. We provide evidence for the success of our approach with an informal evaluation with domain experts. [source]

A Time Model for Time-Varying Visualization

M. Wolter
I.3.6 [Computer Graphics]: Methodology and Techniques; I.6.6 [Simulation and Modelling]: Simulation Output Analysis Abstract The analysis of unsteady phenomena is an important topic for scientific visualization. Several time-dependent visualization techniques exist, as well as solutions for dealing with the enormous size of time-varying data in interactive visualization. Many current visualization toolkits support displaying time-varying data sets. However, for the interactive exploration of time-varying data in scientific visualization, no common time model that describes the temporal properties which occur in the visualization process has been established. In this work, we propose a general time model which classifies the time frames of simulation phenomena and the connections between different time scales in the analysis process. This model is designed for intuitive interaction with time in visualization applications for the domain expert as well as for the developer of visualization tools. We demonstrate the benefits of our model by applying it to two use cases with different temporal properties. [source]

Scalable real-time animation of rivers

Qizhi Yu
Many recent games and applications target the interactive exploration of realistic large scale worlds. These worlds consist mostly of static terrain models, as the simulation of animated fluids in these virtual worlds is computationally expensive. Adding flowing fluids, such as rivers, to these virtual worlds would greatly enhance their realism, but causes specific issues: as the user is usually observing the world at close range, small scale details such as waves and ripples are important. However, the large scale of the world makes classical methods impractical for simulating these effects. In this paper, we present an algorithm for the interactive simulation of realistic flowing fluids in large virtual worlds. Our method relies on two key contributions: the local computation of the velocity field of a steady flow given boundary conditions, and the advection of small scale details on a fluid, following the velocity field, and uniformly sampled in screen space. [source]

Interactive Volume Rendering with Dynamic Ambient Occlusion and Color Bleeding

Timo Ropinski
Abstract We propose a method for rendering volumetric data sets at interactive frame rates while supporting dynamic ambient occlusion as well as an approximation to color bleeding. In contrast to ambient occlusion approaches for polygonal data, techniques for volumetric data sets have to face additional challenges, since by changing rendering parameters, such as the transfer function or the thresholding, the structure of the data set and thus the light interactions may vary drastically. Therefore, during a preprocessing step which is independent of the rendering parameters we capture light interactions for all combinations of structures extractable from a volumetric data set. In order to compute the light interactions between the different structures, we combine this preprocessed information during rendering based on the rendering parameters defined interactively by the user. Thus our method supports interactive exploration of a volumetric data set but still gives the user control over the most important rendering parameters. For instance, if the user alters the transfer function to extract different structures from a volumetric data set the light interactions between the extracted structures are captured in the rendering while still allowing interactive frame rates. Compared to known local illumination models for volume rendering our method does not introduce any substantial rendering overhead and can be integrated easily into existing volume rendering applications. In this paper we will explain our approach, discuss the implications for interactive volume rendering and present the achieved results. [source]

Teaching, Exploring, Learning,Developing Tutorials for In-Class Teaching and Self-Learning

S. Beckhaus
Abstract This paper presents an experience report on a novel approach for a course on intermediate and advanced computer graphics topics. The approach uses Teachlet Tutorials, a combination of traditional seminar,type teaching with interactive exploration of the content by the audience, plus development of self-contained tutorials on the topic. In addition to a presentation, an interactive software tool is developed by the students to assist the audience in learning and exploring the topic's details. This process is guided through set tasks. The resulting course material is developed for two different contexts: (a) for classroom presentation and (b) as an interactive, self-contained, self-learning tutorial. The overall approach results in a more thorough understanding of the topic both for the student teachers as well as for the class participants. In addition to detailing the Teachlet Tutorial approach, this paper presents our experiences implementing the approach in our Advanced Computer Graphics course and presents the resultant projects. Most of the final Teachlet Tutorials were surprisingly good and we had excellent feedback from the students on the approach and course. [source]

Argumentation within deductive reasoning

Armin Fiedler
Deductive reasoning is an area related to argumentation where machine-based techniques, notably theorem proving, can contribute substantially to the formation of arguments. However, making use of the functionality of theorem provers for this issue is associated with a number of difficulties and, as we will demonstrate, requires considerable effort for obtaining reasonable results. Aiming at the exploitation of machine-oriented reasoning for human-adequate argumentation in a broader sense, we present our model for producing proof presentations from machine-oriented inference structures. Capabilities of the model include adaptation to human-adequate degrees of granularity and explicitness in the underlying argumentation and interactive exploration of proofs. Enhancing capabilities in all these respects, even just those we have addressed so far, does not only improve the interactive use of theorem provers, but shows they are essential ingredients to support the functionality of dialog-oriented tutorial systems in formal domains. 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 49,70, 2007. [source]

Evaluation of software for introducing protein structure

Visualization, simulation
Abstract Communicating an understanding of the forces and factors that determine a protein's structure is an important goal of many biology and biochemistry courses at a variety of levels. Many educators use computer software that allows visualization of these complex molecules for this purpose. Although visualization is in wide use and has been associated with student learning, it is quite challenging to develop visualizations that allow students to interactively observe the effects of altered amino acid sequence on protein structure. A software simulation, the protein investigator (PI), has been developed to specifically facilitate this type of exploration. When using the PI, students enter or edit an amino acid sequence; the software then simulates its folding in two dimensions using the major forces involved in protein structure. This study explores freshman undergraduate students' use of visualization and simulation when learning about protein structure. It also evaluates some of the learning outcomes from these two approaches. Our results show that simulation leads to similar learning outcomes as visualization. Because simulation allows a more interactive exploration, a combination of the two approaches may be an effective approach to introducing the basic principles of protein structure. [source]