The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform

Thomas Ertl - One of the best experts on this subject based on the ideXlab platform.

  • Visualization of Temporal Similarity in Field Data
    IEEE Transactions on Visualization and Computer Graphics, 2012
    Co-Authors: Steffen Frey, Filip Sadlo, Thomas Ertl
    Abstract:

    This paper presents a visualization approach for detecting and exploring similarity in the temporal variation of field data. We provide an Interactive Technique for extracting correlations from similarity matrices which capture temporal similarity of univariate functions. We make use of the concept to extract periodic and quasiperiodic behavior at single (spatial) points as well as similarity between different locations within a field and also between different data sets. The obtained correlations are utilized for visual exploration of both temporal and spatial relationships in terms of temporal similarity. Our entire pipeline offers visual interaction and inspection, allowing for the flexibility that in particular time-dependent data analysis Techniques require. We demonstrate the utility and versatility of our approach by applying our implementation to data from both simulation and measurement.

  • Texture-based visualization of unsteady 3d flow by real-time advection and volumetric illumination
    IEEE Transactions on Visualization and Computer Graphics, 2007
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a 3D graphics processing unit (GPU)-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. We investigate two alternative methods for the volumetric illumination of the result of texture advection: First, gradient-based illumination that employs a real-time computation of gradients, and, second, line-based lighting based on illumination in codimension 2. In addition to the Phong model, perception-guided rendering methods are considered, such as cool/warm shading, halo rendering, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions. GPU implementation aspects, performance measurements, and a discussion of results are included to demonstrate our visualization approach.

  • Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
    EuroVis, 2005
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.

  • Frame-to-frame coherent halftoning in image space
    Proceedings Theory and Practice of Computer Graphics 2004., 2004
    Co-Authors: M. Eissele, Daniel Weiskopf, Thomas Ertl
    Abstract:

    We present an Interactive Technique for generating halftoning animations in image space. We specifically consider a halftoning approach that uses screening methods to achieve shading, brightness, and texture by placing varying patterns. Our Technique transports the screening patterns in a frame-to-frame coherent manner according to the velocity of each fragment on the image plane. We show how the algorithm is mapped to programmable graphics hardware to achieve Interactive frame rates. Our approach can be used for any screening-based halftoning Technique, and therefore different nonphotorealistic image-space rendering styles, including dithering, screening, stippling, and hatching, can be utilized to generate real-time frame-to-frame coherent animations

  • VeCHArt: Visually Enhanced Comparison of Historic Art Using an Automated Line-based Synchronization Technique
    IEEE Transactions on Visualization and Computer Graphics, 1
    Co-Authors: Hermann Pfluger, Dennis Thom, Anna Christina Schutz, Daniela Bohde, Thomas Ertl
    Abstract:

    The analysis of subtle deviations between different versions of historical prints has been a long-standing challenge in art history research. So far, this challenge has required extensive domain knowledge, fine-tuned expert perception, and time-consuming manual labor. In this paper we introduce an explorative visual approach to facilitate fast and accurate support for the task of comparing differences between prints such as engravings and woodcuts. To this end, we have developed a customized algorithm that detects similar stroke-patterns in prints and matches them in order to allow visual alignment and automated deviation highlighting. Our visual analytics system enables art history researchers to quickly detect, document, and categorize qualitative and quantitative discrepancies, and to analyze these discrepancies using comprehensive interactions. To evaluate our approach, we conducted a user study involving both experts on historical prints and laypeople. Using our new Interactive Technique, our subjects found about 20% more differences compared to regular image viewing software as well as "paper-based" comparison. Moreover, the laypeople found the same differences as the experts when they used our system, which was not the case for conventional methods. Informal feedback showed that both laypeople and experts strongly preferred employing our system to working with conventional methods.

Daniel Weiskopf - One of the best experts on this subject based on the ideXlab platform.

  • Texture-based visualization of unsteady 3d flow by real-time advection and volumetric illumination
    IEEE Transactions on Visualization and Computer Graphics, 2007
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a 3D graphics processing unit (GPU)-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. We investigate two alternative methods for the volumetric illumination of the result of texture advection: First, gradient-based illumination that employs a real-time computation of gradients, and, second, line-based lighting based on illumination in codimension 2. In addition to the Phong model, perception-guided rendering methods are considered, such as cool/warm shading, halo rendering, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions. GPU implementation aspects, performance measurements, and a discussion of results are included to demonstrate our visualization approach.

  • Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
    EuroVis, 2005
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.

  • Frame-to-frame coherent halftoning in image space
    Proceedings Theory and Practice of Computer Graphics 2004., 2004
    Co-Authors: M. Eissele, Daniel Weiskopf, Thomas Ertl
    Abstract:

    We present an Interactive Technique for generating halftoning animations in image space. We specifically consider a halftoning approach that uses screening methods to achieve shading, brightness, and texture by placing varying patterns. Our Technique transports the screening patterns in a frame-to-frame coherent manner according to the velocity of each fragment on the image plane. We show how the algorithm is mapped to programmable graphics hardware to achieve Interactive frame rates. Our approach can be used for any screening-based halftoning Technique, and therefore different nonphotorealistic image-space rendering styles, including dithering, screening, stippling, and hatching, can be utilized to generate real-time frame-to-frame coherent animations

Tobias Schafhitzel - One of the best experts on this subject based on the ideXlab platform.

  • Texture-based visualization of unsteady 3d flow by real-time advection and volumetric illumination
    IEEE Transactions on Visualization and Computer Graphics, 2007
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a 3D graphics processing unit (GPU)-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. We investigate two alternative methods for the volumetric illumination of the result of texture advection: First, gradient-based illumination that employs a real-time computation of gradients, and, second, line-based lighting based on illumination in codimension 2. In addition to the Phong model, perception-guided rendering methods are considered, such as cool/warm shading, halo rendering, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions. GPU implementation aspects, performance measurements, and a discussion of results are included to demonstrate our visualization approach.

  • Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
    EuroVis, 2005
    Co-Authors: Daniel Weiskopf, Tobias Schafhitzel, Thomas Ertl
    Abstract:

    This paper presents an Interactive Technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.

Steffen Frey - One of the best experts on this subject based on the ideXlab platform.

  • Visualization of Temporal Similarity in Field Data
    IEEE Transactions on Visualization and Computer Graphics, 2012
    Co-Authors: Steffen Frey, Filip Sadlo, Thomas Ertl
    Abstract:

    This paper presents a visualization approach for detecting and exploring similarity in the temporal variation of field data. We provide an Interactive Technique for extracting correlations from similarity matrices which capture temporal similarity of univariate functions. We make use of the concept to extract periodic and quasiperiodic behavior at single (spatial) points as well as similarity between different locations within a field and also between different data sets. The obtained correlations are utilized for visual exploration of both temporal and spatial relationships in terms of temporal similarity. Our entire pipeline offers visual interaction and inspection, allowing for the flexibility that in particular time-dependent data analysis Techniques require. We demonstrate the utility and versatility of our approach by applying our implementation to data from both simulation and measurement.

Ying-en Ge - One of the best experts on this subject based on the ideXlab platform.

  • Vehicle Scheduling of Single-Line Bus Service Using Operational Strategies
    IEEE Transactions on Intelligent Transportation Systems, 2019
    Co-Authors: Chunyan Tang, Avishai Ceder, Shengchuan Zhao, Ying-en Ge
    Abstract:

    Vehicle scheduling is an important component of the transit operations planning process because it is directly related to the number of vehicles required for covering all trips. However, in practice, vehicles are not scheduled by a very efficient approach, related to the fact that all vehicles use one type of operation strategy-full operation strategy-for meeting unbalanced demand patterns. This paper proposes a methodology to reduce the required number of vehicles by adjusting a few trips to operate by other strategies, including limited stop, short turn, deadheading, and mixed strategies. This proposed methodology is based on a graphical human-machine Interactive Technique, called deficit function (DF). The DF allows schedulers to select a variable trip schedule for reducing the number of vehicles using optimal determination of the best applied strategies. The process of adjusting variable trips to accommodate different strategies may result in passenger travel time changes. Two optimization models are developed to minimize these changes and determine a set of stops served by the variable trip schedule. This proposed methodology has been applied to a detailed example and a case study in Paris, France. The results show that the adjustment of a few trips to use certain strategies can reduce the number of buses required by three.