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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Article
  • Peer Reviewed
IDAV Publications (2008)
    Cover page: On the Role of Domain-specific Knowledge in the Visualization of Technical Flows
    • Article
    • Peer Reviewed
    IDAV Publications (2007)
    The recently introduced notion of Finite-Time Lyapunov Exponent to characterize Coherent Lagrangian Structures provides a powerful framework for the visualization and analysis of complex technical flows. Its definition is simple and intuitive, and it has a deep theoretical foundation. While the application of this approach seems straightforward in theory, the associated computational cost is essentially prohibitive. Due to the Lagrangian nature of this technique, a huge number of particle paths must be computed to fill the space-time flow domain. In this paper, we propose a novel scheme for the adaptive computation of FTLE fields in two and three dimensions that significantly reduces the number of required particle paths. Furthermore, for three-dimensional flows, we show on several examples that meaningful results can be obtained by restricting the analysis to a well-chosen plane intersecting the flow domain. Finally, we examine some of the visualization aspects of FTLE-based methods and introduce several new variations that help in the analysis of specific aspects of a flow.
      Cover page: Efficient Computation and Visualization of Coherent Structures in Fluid Flow Applications
      • Article
      • Peer Reviewed
      IDAV Publications (2008)
      We present a novel approach for the direct computation of integral surfaces in general vector fields. As opposed to previous work, which we analyze in detail, our approach is based on a separation of integral surface computation into two stages: surface approximation and generation of a graphical representation. This allows us to overcome several limitations of previous techniques. We first describe an algorithm for surface integration that approximates a series of timelines using iterative refinement and computes a skeleton of the integral surface. In a second step, we generate a well-conditioned triangulation. The presented approach allows a highly accurate treatment of very large time-varying vector fields in an efficient, streaming fashion. We examine the properties of the presented methods on several example datasets and perform a numerical study of its correctness and accuracy. Finally, we examine some visualization aspects of integral surfaces.
        Cover page: Generation of Accurate Integral Surfaces in Time-Dependent Vector Fields
        • Article
        • Peer Reviewed
        IDAV Publications (2008)
        The notions of Finite-Time Lyapunov Exponent (FTLE) and Lagrangian Coherent Structures provide a strong framework for the analysis and visualization of complex technical flows. Their definition is simple and intuitive, and they are built on a deep theoretical foundation. We apply these concepts to enable the analysis of flows in the immediate vicinity of the boundaries of flow-embedded objects by limiting the Lagrangian analysis to surfaces closely neighboring these boundaries. To this purpose, we present an approach to approximate FTLE fields over such surfaces. Furthermore, we achieve an effective depiction of boundary-related flow structures such as separation and attachment over object boundaries and specific insight into the surrounding flow using several specifically chosen visualization techniques. We document the applicability of our methods by presenting a number of application examples.
          Cover page: Lagrangian Visualization of Flow-Embedded Surface Structures
          • Article
          • Peer Reviewed
          IDAV Publications (2010)
          The structure of fiber tracts in DT-MRI data presents a challenging problem for visualization and analysis. We derive visualization of such traces from a local coherence measure and achieve much improved visual segmentation. We introduce a coherence measure defined for fiber tracts. This quantitative assessment is based on infinitesimal deviations of neighboring tracts and allows identification and segmentation of coherent fiber regions. We use a hardware-accelerated implementation to achieve interactive visualization on slices and provide several approaches to visualize coherence information. Furthermore, we enhance existing techniques by combining them with coherence. We demonstrate our method on both a canine heart, where the myocardial structure is visualized, and a human brain, where we achieve detailed visualization of major and minor fiber bundles in a quality similar to and exceeding fiber clustering approaches. Our approach allows detailed and fast visualization of important anatomical structures in DT-MRI data sets.
            Cover page: Direct Visualization of Fiber Information by Coherence
            • Article
            LBL Publications (2006)
            The Visualization and Analytics Center for Enabling Technologies (VACET) focuses on leveraging scientific visualization and analytics software technology as an enabling technology for increasing scientific productivity and insight. Advances in computational technology have resulted in an "information big bang," which in turn has created a significant data understanding challenge. This challenge is widely acknowledged to be one of the primary bottlenecks in contemporary science. The vision for our Center is to respond directly to that challenge by adapting, extending, creating when necessary and deploying visualization and data understanding technologies for our science stakeholders. Using an organizational model as a SciDAC Center, we are well positioned to be responsive to the needs of a diverse set of scientific stakeholders in a coordinated fashion using a range of visualization, mathematics, statistics, computer and computational science and data management technologies.
              Cover page: Meet the Proposed Visualization and Analytics Center for Enabling Technologies
              • Article
              • Peer Reviewed
              Lawrence Berkeley National Laboratory (2008)

              The Visualization and Analytics Center for Enabling Technologies (VACET) focuses on leveraging scientific visualization and analytics software technology as an enabling technology for increasing scientific productivity and insight. Advances in computational technology have resulted in an 'information big bang,' which in turn has created a significant data understanding challenge. This challenge is widely acknowledged to be one of the primary bottlenecks in contemporary science. The vision of VACET is to adapt, extend, create when necessary, and deploy visual data analysis solutions that are responsive to the needs of DOE's computational and experimental scientists. Our center is engineered to be directly responsive to those needs and to deliver solutions for use in DOE's large open computing facilities. The research and development directly target data understanding problems provided by our scientific application stakeholders. VACET draws from a diverse set of visualization technology ranging from production quality applications and application frameworks to state-of-the-art algorithms for visualization, analysis, analytics, data manipulation, and data management.

                Cover page: SciDAC Visualization and Analytics Center for Enabling Technologies
                • Article
                Lawrence Berkeley National Laboratory (2006)

                The SciDAC2 Visualization and Analytics Center for Enabling Technologies (VACET) began operation on 10/1/2006. This document, dated 11/27/2006, is the first version of the VACET project management plan. It was requested by and delivered to ASCR/DOE. It outlines the Center's accomplishments in the first six weeks of operation along with broad objectives for the upcoming future (12-24 months).

                  Cover page: SciDAC Visualization and Analytics Center for Enabling Technology
                  • Article
                  Lawrence Berkeley National Laboratory (2008)

                  This paper accompanies a poster that is being presented at the SciDAC 2006 meeting in Denver, CO. This project focuses on leveraging scientific visualization and analytics software technology as an enabling technology for increasing scientific productivity and insight. Advances incomputational technology have resulted in an "information big bang," which in turn has createda significant data understanding challenge. This challenge is widely acknowledged to be one of the primary bottlenecks in contemporary science. The vision for our Center is to respond directly to that challenge by adapting, extending, creating when necessary and deploying visualization and data understanding technologies for our science stakeholders. Using an organizational model as a Visualization and Analytics Center for Enabling Technologies (VACET), we are well positioned to be responsive to the needs of a diverse set of scientific stakeholders in a coordinated fashion using a range of visualization, mathematics, statistics, computer and computational science and data management technologies.

                    Cover page: VACET: Proposed SciDAC2 Visualization and Analytics Center for Enabling Technologies
                    • Article
                    • Peer Reviewed
                    IDAV Publications (2007)
                    The Visualization and Analytics Center for Enabling Technologies (VACET) focuses on leveraging scientific visualization and analytics software technology as an enabling technology for increasing scientific productivity and insight. Advanced in computational technology have resulted in an ``information big bang,'' which in turn has created a significant data understanding challenge. This challenge is widely acknowledged to be one of the primary bottlenecks in contemporary science. The vision of VACET is to adapt, extend, create when necessary, and deploy visual data analysis solutions that are responsive to the needs of DoE's computational and experimental scientists. Our center is engineered to be directly responsive to those needs and to deliver solutions for use in DoE's large open computing facilities. The research and development directly target data understanding problems provided by our scientific application stakeholders. FACET draws from a diverse set of visualization technology ranging from production quality applications and application frameworks to state-of-the-art algorithms for visualization, analysis , analytics, data manipulation, and data management.
                      Cover page: SciDAC Visualizatiopn and Analytics Center for Enabling Technology
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