Ovis: A framework for visual analysis of ocean forecast ensembles

pre-printWe present a novel integrated visualization system that enables interactive visual analysis of ensemble simulations of the sea surface height that is used in ocean forecasting. The position of eddies can be derived directly from the sea surface height and our visualization approach enables their interactive exploration and analysis.The behavior of eddies is important in different application settings of which we present two in this paper. First, we show an application for interactive planning of placement as well as operation of off-shore structures using real-world ensemble simulation data of the Gulf of Mexico. Off-shore structures, such as those used for oil exploration, are vulnerable to hazards caused by eddies, and the oil and gas industry relies on ocean forecasts for efficient operations. We enable analysis of the spatial domain, as well as the temporal evolution, for planning the placement and operation of structures.Eddies are also important for marine life. They transport water over large distances and with it also heat and other physical properties as well as biological organisms. In the second application we present the usefulness of our tool, which could be used for planning the paths of autonomous underwater vehicles, so called gliders, for marine scientists to study simulation data of the largely unexplored Red Sea

Artifact-Based Rendering: Harnessing Natural and Traditional Visual Media for More Expressive and Engaging 3D Visualizations

We introduce Artifact-Based Rendering (ABR), a framework of tools, algorithms, and processes that makes it possible to produce real, data-driven 3D scientific visualizations with a visual language derived entirely from colors, lines, textures, and forms created using traditional physical media or found in nature. A theory and process for ABR is presented to address three current needs: (i) designing better visualizations by making it possible for non-programmers to rapidly design and critique many alternative data-to-visual mappings; (ii) expanding the visual vocabulary used in scientific visualizations to depict increasingly complex multivariate data; (iii) bringing a more engaging, natural, and human-relatable handcrafted aesthetic to data visualization. New tools and algorithms to support ABR include front-end applets for constructing artifact-based colormaps, optimizing 3D scanned meshes for use in data visualization, and synthesizing textures from artifacts. These are complemented by an interactive rendering engine with custom algorithms and interfaces that demonstrate multiple new visual styles for depicting point, line, surface, and volume data. A within-the-research-team design study provides early evidence of the shift in visualization design processes that ABR is believed to enable when compared to traditional scientific visualization systems. Qualitative user feedback on applications to climate science and brain imaging support the utility of ABR for scientific discovery and public communication.Comment: Published in IEEE VIS 2019, 9 pages of content with 2 pages of references, 12 figure

Multi-resolution visualization of geographic network traffic

Flow visualization techniques are vastly used to visualize scientific data among many fields including meteorology, computational fluid dynamics, medical visualization and aerodynamics. In this thesis, we employ flow visualization techniques in conjunction with conventional network visualization methods to represent geographic network traffic data. The proposed visualization system integrates two visualization techniques, flow visualization and node-link diagram, in a level of detail framework. While flow visualization emphasizes general trends, node-link diagram visualization concentrates on the detailed analysis of the data. Usability studies are performed to evaluate the success of our approach

Level set and PDE methods for visualization

Notes from IEEE Visualization 2005 Course #6, Minneapolis, MN, October 25, 2005. Retrieved 3/16/2006 from http://www.cs.drexel.edu/~david/Papers/Viz05_Course6_Notes.pdf.Level set methods, an important class of partial differential equation (PDE) methods, define dynamic surfaces implicitly as the level set (isosurface) of a sampled, evolving nD function. This course is targeted for researchers interested in learning about level set and other PDE-based methods, and their application to visualization. The course material will be presented by several of the recognized experts in the field, and will include introductory concepts, practical considerations and extensive details on a variety of level set/PDE applications. The course will begin with preparatory material that introduces the concept of using partial differential equations to solve problems in visualization. This will include the structure and behavior of several different types of differential equations, e.g. the level set, heat and reaction-diffusion equations, as well as a general approach to developing PDE-based applications. The second stage of the course will describe the numerical methods and algorithms needed to implement the mathematics and methods presented in the first stage, including information on implementing the algorithms on GPUs. Throughout the course the technical material will be tied to applications, e.g. image processing, geometric modeling, dataset segmentation, model processing, surface reconstruction, anisotropic geometric diffusion, flow field post-processing and vector visualization. Prerequisites: Knowledge of calculus, linear algebra, computer graphics, visualization, geometric modeling and computer vision. Some familiarity with differential geometry, differential equations, numerical computing and image processing is strongly recommended, but not required

Evaluation of trend localization with multi-variate visualizations

Fig. 1 . Multi-variate visualization techniques we evaluated in our study, from left to right: Brush Strokes, Data-Driven Spots, Oriented Slivers, Color Blending, and Dimensional Stacking. These images depict a tri-county area in central Ohio. The encoded information is generated from a synthetic data set generated for the purposes of the study. See Section 3 for a explanation of the encoding. Abstract-Multi-valued data sets are increasingly common, with the number of dimensions growing. A number of multi-variate visualization techniques have been presented to display such data. However, evaluating the utility of such techniques for general data sets remains difficult. Thus most techniques are studied on only one data set. Another criticism that could be levied against previous evaluations of multi-variate visualizations is that the task doesn't require the presence of multiple variables. At the same time, the taxonomy of tasks that users may perform visually is extensive. We designed a task, trend localization, that required comparison of multiple data values in a multi-variate visualization. We then conducted a user study with this task, evaluating five multivariate visualization techniques from the literature (Brush Strokes, Data-Driven Spots, Oriented Slivers, Color Blending, Dimensional Stacking) and juxtaposed grayscale maps. We report the results and discuss the implications for both the techniques and the task

Simulação numérica de escoamento bidimensional incompressível com obstáculos

Neste trabalho, apresentam-se estudos de casos envolvendo simulação computacional de fluido incompressível com obstáculo. Discute-se a modelagem matemática, via Equações de Navier-Stokes incompressíveis para escoamentos em regime laminar, e discretização via o método de elementos finitos. O presente trabalho é baseado em estudos que possuem resultados clássicos a respeito desta área de estudo, de tal sorte que o objetivo principal não se concentra em pesquisas de novos campos de trabalho, mas sim de análise de pesquisas notáveis e suas respectivas aplicações. A modelagem se deu pelas Equações de Navier Stokes, auxiliadas pela Equação da Continuidade, considerando o fluido incompressível e viscoso e o domínio sendo bidimensional. As simulações computacionais foram obtidas via método dos Elementos Finitos, usando o pacote Gascoigne3D. A discretização no espaço foi feita com elementos quadrangulares lineares, e a discretização no tempo com uma combinação de esquemas de Euler implícito e Cranck-Nicholson. Em cada passo de tempo, a solução das equações não-lineares é obtida por iteração quasi-Newton, onde monitoramos a razão de convergência das iterações e, assim, computamos a solução do modelo numérico. Foram analisados casos clássicos, através de figuras geométricas simples encontradas em grandes obras, representando diferentes obstáculos para o escoamento, tais como objetos circulares, quadrangulares e retangulares. Tendo obtido resultados adequados à teoria, onde estes resultados representam a validação para o código, partiu-se para estudos de caso referentes ao capítulo de resultados de aplicação, com a finalidade de aumentar a referência bibliográfica sobre o assunto.On this work, we show a study about cases involving computational simulation of incompressible fluid with obstacle. We discusses about mathematical modeling, by the laminar and incompressible Navier Stokes equations, and discretization by the Finite Element Method (FEM). This work is based in studies that have classic results about this area, so that the main goal is about the remarkable results and their applications. The mathematical modeling was obtained with the Navier Stokes Equations, aided by the Continuity Equations, considering a incompressible and viscous fluid and the domain 2D. The computational simulations were obtained by the Finite Element Method (FEM), using the Gascoigne3D. The space discretization was made with quadrangular linear elements, and the time discretization was made with a combination of the implicit Euler and Cranck-Nicholson method. In each time step, the solution of the non-linears equations is obtained with Quasi-Newton iteration, and we monitored the convergence reason about the iterations and, this way, compute the obtained values. We studied classic cases, with simple geometric configurations, that represents different obstacles to the flow, like circles, quadrangular and rectangular configurations. When the suitable results was obtained, we considered the code as validated and started results of application, with the main goal of increases the bibliografic reference about that area