Carlos E Scheidegger

• University of Utah

We present a model of visualization design based on algebraic considerations of the visualization process. The model helps characterize visual encodings, guide their design, evaluate their effectiveness, and highlight their shortcomings. The model has three components: the underlying mathematical structure of the data or object being visualized, th...

We propose an approach for verification of volume rendering correctness based on an analysis of the volume rendering integral, the basis of most DVR algorithms. With respect to the most common discretization of this continuous model (Riemann summation), we make assumptions about the impact of parameter changes on the rendered results and derive con...

Consider real-time exploration of large multidimensional spatiotemporal datasets with billions of entries, each defined by a location, a time, and other attributes. Are certain attributes correlated spatially or temporally? Are there trends or outliers in the data? Answering these questions requires aggregation over arbitrary regions of the domain...

Scientists study trajectory data to understand trends in movement patterns, such as human mobility for traffic analysis and urban planning. There is a pressing need for scalable and efficient techniques for analyzing this data and discovering the underlying patterns. In this paper, we introduce a novel technique which we call vector-field $k$-means...

The importance of properly implemented isosurface extraction for verifiable visualization led to a previously published paper on the general Method of Manufactured Solutions (MMS), inclusive of a supportive software infrastructure. This work builds upon that foundation, while significantly extending it. Specifically, we extend previous work on veri...

Graphs are often used to encapsulate relationships between objects. Node-link diagrams, commonly used to visualize graphs, suffer from visual clutter on large graphs. Edge bundling is an effective technique for alleviating clutter and revealing high-level edge patterns. Previous methods for general graph layouts either require a control mesh to gui...

VisWeek 2010 covered the latest visualization and data analysis research and offered an excellent forum for discussing new trends in these fields.

We present a method to characterize the topology of the level sets of trilinearly interpolated scalar fields. Our characterization is based on Morse theory, and in particular a variant called Stratified Morse theory capable of treating the piecewise-smooth aspect of trilinear interpolation. Algorithms such as Marching Cubes generate approximations...

Provenance has become an increasingly important part of documenting, verifying, and reproducing scientific research, but as users seek to extend or share results, it may be impractical to start from the exact original steps due to system configuration differences, library updates, or new algorithms. Although there have been several approaches for...

Visual representations of isosurfaces are ubiquitous in the scientific and engineering literature. In this paper, we present techniques to assess the behavior of isosurface extraction codes. Where applicable, these techniques allow us to distinguish whether anomalies in isosurface features can be attributed to the underlying physical process or to...

We investigate the influence of bandwidth selection in the reconstruction quality of point-based surfaces. While the problem has received relatively little attention in the literature, we show that appropriate selection plays a significant role in the quality of reconstructed surfaces. We show how to compute optimal bandwidths for one class of movi...

Most computational codes that use irregular grids depend on the single worst triangle's quality: skinny triangles can lead to bad performance and numerical instabilities. Marching cubes (MC) is the standard isosurface grid generation algorithm, and, whereas most triangles it generates are good, it almost always generates some bad triangles. Here, w...

Marching Cubes is the most popular isosurface extraction algorithm due to its simplicity, efficiency and robustness. It has been widely studied, improved, and extended. While much early work was concerned with efficiency and correctness issues, lately there has been a push to improve the quality of Marching Cubes meshes so that they can be used in...

Data analysis tasks at an Ocean Observatory require integrative and and domain-specialized use of database, workflow, visualization systems. We describe a platform to support these tasks developed as part of the cyberinfrastructure at the NSF Science and Technology Center for Coastal Margin Observation and Prediction integrating a provenance-aware...

Building visualization and analysis pipelines is a large hurdle in the adoption of visualization and workflow systems by domain scientists. In this paper, we propose techniques to help users construct pipelines by consensus--automatically suggesting completions based on a database of previously created pipelines. In particular, we compute correspon...

Recent results have shown a link between geometric properties of isosurfaces and statistical properties of the underlying sampled data. However, this has two defects: not all of the properties described converge to the same solution, and the statistics computed are not always invariant under isosurface-preserving transformations. We apply Federer's...

Provenance (also referred to as audit trail, lineage, and pedigree) captures information about the steps used to generate a given data product. Such information provides documentation that is key to determining data quality and authorship, and necessary for preserving, reproducing, sharing and publishing the data. Workflow design, in particular for...

We address the problem of bandwidth selection in MLS surfaces. While the problem has received relatively little attention in the literature, we show that appropriate selection plays a critical role in the quality of reconstructed surfaces. We formulate the MLS polynomial fitting step as a kernel regression problem for both noiseless and noisy data....

Currently, there are no general provenance management sys- tems or tools available for existing applications. Our goal is to develop provenance technology that is flexible and adaptable to the wide range of requirements of software applications. By consolidating provenance in- formation for a variety of applications, we can provide a uniform enviro...

The first Provenance Challenge was set up in order to provide a forum for the community to help understand the capabilities of different provenance systems and the expressiveness of their provenance representations. To this end, a Functional Magnetic Resonance Imaging workflow was defined, which participants had to either simulate or run in order t...

SUMMARY VisTrails is a new workflow and provenance management system that provides support for scientific data exploration and visualization. Whereas workflows have been traditionally used to automate repetitive tasks, for applications that are exploratory in nature, change is the norm. VisTrails uses a new change-based provenance mechanism which w...

The use of plotting techniques to comprehend scalar functions is ubiquitous in science and engineering. An effective plot uses features such as first and second derivatives to convey critical and inflection points, which help portray the overall behavior of functions around a region of interest. Direct volume rendering is an effective method for pl...

We show how work flow systems can be augmented to leverage provenance information to enhance usability. In particular, we will demonstrate new mechanisms and intuitive user interfaces designed to allow users to query work flows by example and to refine work flows by analogies. These techniques are implemented in VisTrails, an open-source provenance...

Currently, there are no general provenance management sys- tems or tools available for existing applications. Our goal is to develop provenance technology that is exible and adaptable to the wide range of requirements of software applications. By consolidating provenance in- formation for a variety of applications, we can provide a uniform environ-...

While there have been advances in visualization systems, particularly in multi-view visualizations and visual exploration, the process of building visualizations remains a major bottleneck in data exploration. We show that provenance metadata collected during the creation of pipelines can be reused to suggest similar content in related visualizatio...

Unstructured volume grids are ubiquitous in scientific computing, and have received substantial interest from the scientific visualization community. In this paper, we take a point-based approach to rendering unstructured grids. In particular, we present a novel method of approximating these irregular elements with point-based primitives amenable t...

— While there have been advances in visualization systems, particularly in multi-view visualizations and visual exploration, the process of building visualizations remains a major bottleneck in data exploration. We show that provenance metadata collected during the creation of pipelines can be reused to suggest similar content in related visualizat...

Moving-Least Squares (MLS) surfaces are a popular way to define a smooth manifold surface from a set of unorganized points without normals. In this paper we present a formulation of MLS surfaces that sheds light on shortcomings of the original technique proposed by Levin, which is based on a two-step minimization procedure. We show that there are c...

The first Provenance Challenge was set up in order to provide a forum for the community to help understand the capabilities of different provenance systems and the expressiveness of their provenance representations. To this end, a Functional Magnetic Resonance Imaging workflow was defined, which participants had to either simulate or run in order t...

Isosurfaces are ubiquitous in many fields, including visualization, graphics, and vision. They are often the main computational component of important processing pipelines (e.g. , surface reconstruction), and are heavily used in practice. The classical approach to compute isosurfaces is to apply the Marching Cubes algorithm, which although robust a...

We propose a novel surface remeshing algorithm. While many remeshing algorithms are based on global parametrization or local mesh optimization, our algorithm is closely related to surface reconstruction techniques and it requires no explicit parameterization. Our approach is based on the advancing-front paradigm, and it can be used to both incremen...

We give an overview of VisTrails, a system that provides an infrastructure for systematically capturing detailed provenance and streamlining the data exploration process. A key feature that sets Vis-Trails apart from previous visualization and scientific workflow systems is a novel action-based mechanism that uniformly captures provenance for data...

Scientists are now faced with an incredible volume of data to analyze. To successfully analyze and validate various hypotheses, it is necessary to pose several queries, correlate disparate data, and create insightful visualizations of both the simulated processes and observed phenomena. Data exploration through visualization requires scientists to...

Scientists are now faced with an incredible volume of data to analyze. To successfully analyze and validate various hypothesis, it is necessary to pose several queries, correlate disparate data, and create insightful visualizations of both the simulated processes and observed phenomena. Often, insight comes from comparing the results of multiple vi...

Abstract The explosive growth,in integration technology,and,the parallel nature of rasterization-based graphics,APIs changed the panorama of consumer-level graphics: today, GPUs are cheap, fast and ubiquitous. We show how to harness the computational,power,of GPUs and solve the incompressible,Navier-Stokes fluid equations significantly faster (more...

VisTrails is a new system that enables interactive multiple-view visualizations by simplifying the creation and maintenance of visualization pipelines, and by optimizing their execution. It provides a general infrastructure that can be combined with existing visualization systems and libraries. A key component of VisTrails is the visualization trai...

We introduce an algorithm for constructing a high-quality triangulation directly from Point Set Surfaces. Our algorithm requires no intermediate representation and no post-processing of the output, and naturally handles noisy input data, typically in the form of a set of registered range scans. It creates a triangulation where triangle size respect...

Point-based modeling and rendering is an active area of research in Computer Graphics. The concept of points with attributes (e.g. normals) is usually referred to as surfels, and many algorithms have been devised to their effi- cient manipulation and rendering. Key to the efficiency of many methods is the use of partitioning schemes, and usually ax...

Modern programmable graphics hardware offers sufficient computing power to suggest the implementation of traditional algorithms on the graphics processor. This paper describes a complete implementation of a standard technique to solve the incompressible Navier-Stokes fluid equations running entirely on the GPU: the SMAC (simplified marker and cell)...

The recent development of graphics hardware is presenting a change in the implementation of the graphics pipeline, from a fixed set of functions, to user- developed special programs to be executed on a per-vertex or per-fragment basis. This programmability allows the efficient implementation of different algorithms directly on the graphics hardware...

Data exploration in radiation oncology requires the creation of a large number of visualizations. For treatment planning, detailed information about the processes used to manipulate data collected and to create visualizations is needed for assessing the quality of the results. Current visualization systems allow the interactive cre- ation and manip...