IEEE VIS Publication Dataset

This case study describes a technique for the three-dimensional analysis of the internal microscopic structure (microstructure) of materials. This technique consists of incrementally polishing through a thin layer (approximately 0.2 μm) of material, chemically etching the polished surface, applying reference marks, and performing optical or scanning electron microscopy on selected areas. The series of images are then processed employing AVS and other visualization software to obtain a 3D reconstruction of the material. We describe how we applied this technique to an alloy steel to study the morphology, connectivity, and distribution of cementite precipitates formed during thermal processing. The results showed microstructural features not previously identified with traditional 2D techniques.

We present a novel approach to visualize and explore unstructured text. The underlying technology, called TOPIC-O-GRAPHY TM, applies wavelet transforms to a custom digital signal constructed from words within a document. The resultant multiresolution wavelet energy is used to analyze the characteristics of the narrative flow in the frequency domain, such as theme changes, which is then related to the overall thematic content of the text document using statistical methods. The thematic characteristics of a document can be analyzed at varying degrees of detail, ranging from section-sized text partitions to partitions consisting of a few words. Using this technology, we are developing a visualization system prototype known as TOPIC ISLANDS to browse a document, generate fuzzy document outlines, summarize text by levels of detail and according to user interests, define meaningful subdocuments, query text content, and provide summaries of topic evolution.

3D time-varying unstructured and structured data sets are difficult to visualize and analyze because of the immense amount of data involved. These data sets contain many evolving amorphous regions, and standard visualization techniques provide no facilities to aid the scientist to follow regions of interest. In this paper, we present a basic framework for the visualization of time-varying data sets, and a new algorithm and data structure to track volume features in unstructured scalar data sets. The algorithm and data structure are general and can be used for structured, curvilinear, adaptive and hybrid grids as well. The features tracked can be any type of connected regions. Examples are shown from ongoing research.

We propose a new approach to polygonal isosurface extraction that is based on extracting only the visible portion of the isosurface. The visibility tests are done in two phases. First, coarse visibility tests are performed in software to determine the visible cells. These tests are based on hierarchical tiles and shear-warp factorization. The second phase resolves the visible portions of the extracted triangles and is accomplished by the graphics hardware. While the latest isosurface extraction methods have effectively eliminated the search phase bottleneck, the cost of constructing and rendering the isosurface remains high. Many of today's large datasets contain very large and complex isosurfaces that can easily overwhelm even state-of-the-art graphics hardware. The proposed approach is output sensitive and is thus well suited for remote visualization applications where the extraction and rendering phases are done on a separate machines.

Medical image analysis is shifting from current film oriented light screen environments to computer environments that involve viewing and analyzing large sets of images on a computer screen. Magnetic resonance imaging (MRI) studies, in particular, can involve many images. The paper examines how best to meet the needs of radiologists in a computational environment. To this end, a field study was conducted to observe radiologists' interactions during MRI analysis in the traditional light screen environment. Key issues uncovered involve control over focus and context, dynamic grouping of images and retrieval of images and image groups. To address the problem of focus and context, existing layout adjustment and magnification techniques are explored to provide the most appropriate solution. Our interest is in combining the methodologies of human computer interaction studies with computational presentation possibilities to design a visual environment for the crucial field of medical image analysis.

We describe an aircraft design problem in high dimensional space, with D typically being 10 to 30. In some respects this is a classic optimization problem, where the goal is to find the point that minimizes an objective function while satisfying a set of constraints. However, evaluating an individual point is expensive, and the high dimensionality makes many approaches to solving the problem infeasible. The difficulty of the problem means that aircraft designers would benefit from any insights that can be provided. We discuss how simple visualizations have already proved beneficial, and then describe how visualization might be of further help in the future.

The anterior surface of the eye ('cornea') is extremely important for good sight. Instruments measuring corneal shape conventionally visualize the surface characteristics by mapping the instantaneous radius of curvature onto a rainbow colour scale. This technique is known to have important drawbacks. Firstly, not corneal shape itself is visualized, but rather second order surface properties. Secondly, the type of colouring produces well documented artifacts. We discuss visualization techniques for a more direct representation of the data. In a three part display, shape deviations are presented as a height surface in one window, height lines superimposed over the input image in another, and a colour mapped representation of the mean normal radius of curvature in a third. With the aid of some typical examples, it is shown that these visualizations are easy to interpret by the physician and overcome the limitations of the conventional techniques.

Scalar fields arise in every scientific application. Existing scalar visualization techniques require that the user infers the global scalar structure from what is frequently an insufficient display of information. We present a visualization technique which numerically detects the structure at all scales, removing from the user the responsibility of extracting information implicit in the data, and presenting the structure explicitly for analysis. We further demonstrate how scalar topology detection proves useful for correct visualization and image processing applications such as image co-registration, isocontouring, and mesh compression.

This paper discusses techniques for visualizing structure in video data and other data sets that represent time snapshots of physical phenomena. Individual frames of a movie are treated as vectors and projected onto a low-dimensional subspace spanned by principal components. Movies can be compared and their differences visualized by analyzing the nature of the subspace and the projections of multiple movies onto the same subspace. The approach is demonstrated on an application in neurobiology in which the electrical response of a visual cortex to optical stimulation is imaged onto a high-speed photodiode array to produce a cortical movie. Techniques for sampling movies over a single trial and multiple trials are discussed. The approach provides the traditional benefits of principal component analysis (compression, noise reduction and classification) and also allows the visual separation of spatial and temporal behavior.

Within biological systems, water molecules undergo continuous stochastic Brownian motion. The diffusion rate can give clues to the structure of the underlying tissues. In some tissues, the rate is anisotropic. Diffusion-rate images can be calculated from diffusion-weighted MRI. A 2D diffusion tensor image (DTI) and an associated anatomical scalar field define seven values at each spatial location. We present two new methods for visually representing DTIs. The first method displays an array of ellipsoids, where the shape of each ellipsoid represents one tensor value. The ellipsoids are all normalized to approximately the same size so that they can be displayed simultaneously in context. The second method uses concepts from oil painting to represent the seven-valued data with multiple layers of varying brush strokes. Both methods successfully display most or all of the information in DTIs and provide exploratory methods for understanding them. The ellipsoid method has a simpler interpretation and explanation than the painting-motivated method; the painting-motivated method displays more of the information and is easier to read quantatively. We demonstrate the methods on images of the mouse spinal cord. The visualizations show significant differences between spinal cords from mice suffering from experimental allergic encephalomyelitis and spinal cords from wild-type mice. The differences are consistent with differences shown histologically and suggest that our new non-invasive imaging methodology and visualization of the results could have early diagnostic value for neurodegenerative diseases.

A computer animated movie was produced, illustrating both 2D and 3D Hilbert curves, and showing the transition from 2D to 3D with the help of volume rendering.

A new tool for real time visualization of acoustic sound fields has been developed for a new sound spatialization theatre. The theatre is described and several applications of the acoustic and volumetric modeling software are presented. The visualization system described is a valuable tool for spatial sound researchers, sound engineers and composers using CNMAT's sound spatialization theatre. Further work is in progress on the adaptation of better acoustic simulation methods (M. Monks et al., 1996) for more accurate display of the quality of the reverberant field. The room database will be automatically extracted from a model built with 3D modeling software. Volume visualization strategies are being explored to display sounds in spectral and impulse response form.

We develop multiresolution models for analyzing and visualizing two-dimensional flows over curvilinear grids. Our models are based upon nested spaces of piecewise defined functions defined over nested curvilinear grid domains. The nested domains are selected so as to maintain the original geometry of the inner boundary. We first give the refinement and decomposition equations for Haar wavelets over these domains. Next, using lifting techniques we develop and show examples of piecewise linear wavelets over curvilinear grids.

In information visualization, as the volume and complexity of the data increases, researchers require more powerful visualization tools that enable them to more effectively explore multidimensional datasets. We discuss the general utility of a novel visualization spreadsheet framework. Just as a numerical spreadsheet enables exploration of numbers, a visualization spreadsheet enables exploration of visual forms of information. We show that the spreadsheet approach facilitates certain information visualization tasks that are more difficult using other approaches. Unlike traditional spreadsheets, which store only simple data elements and formulas in each cell, a visualization spreadsheet cell can hold an entire complex data set, selection criteria, viewing specifications, and other information needed for a full-fledged information visualization. Similarly, inter-cell operations are far more complex, stretching beyond simple arithmetic and string operations to encompass a range of domain-specific operators. We have built two prototype systems that illustrate some of these research issues. The underlying approach in our work allows domain experts to define new data types and data operations, and enables visualization experts to incorporate new visualizations, viewing parameters, and view operations.

We introduce the adaptive information visualization method for hypermedia and the WWW based on the user's multiple viewpoints. We propose two graphical interfaces, the CVI and the RF-Cone. The CVI is the interface for interactive viewpoint selection. We can select a viewpoint reflecting our interests by using the CVI. According to the given viewpoint, the RF-Cone adaptively organizes the 3D representation of the hypermedia so that we can understand the semantic and structural relationship of the hypermedia and easily retrieve the information. Combining these methods, we have developed the WWW visualization system which can provide highly efficient navigation.

We describe a system that allows the user to rapidly construct program visualizations over a variety of data sources. Such a system is a necessary foundation for using visualization as an aid to software understanding. The system supports an arbitrary set of data sources so that information from both static and dynamic analysis can be combined to offer meaningful software visualizations. It provides the user with a visual universal-relation front end that supports the definition of queries over multiple data sources without knowledge of the structure or contents of the sources. It uses a flexible back end with a range of different visualizations, most geared to the efficient display of large amounts of data. The result is a high-quality, easy-to-define program visualization that can address specific problems and hence is useful for software understanding. The overall system is flexible and extensible in that both the underlying data model and the set of visualizations are defined in resource files.

Interactive visualization techniques allow data exploration to be a continuous process, rather than a discrete sequence of queries and results as in traditional database systems. However limitations in expressive power of current visualization systems force users to go outside the system and form a new dataset in order to perform certain operations, such as those involving the relationship among multiple objects. Further, there is no support for integrating data from the new dataset into previous visualizations, so users must recreate them. Visage's information centric paradigm provides an architectural hook for linking data across multiple queries, removing this overhead. This paper describes the addition to Visage of a visual query language, called VQE, which allows users to express more complicated queries than in previous interactive visualization systems. Visualizations can be created from queries and vice versa. When either is updated, the other changes to maintain consistency.

A dynamic query interface (DQI) is a database access mechanism that provides continuous real-time feedback to the user during query formulation. Previous work shows that DQIs are elegant and powerful interfaces to small databases. Unfortunately, when applied to large databases, previous DQI algorithms slow to a crawl. We present a new incremental approach to DQI algorithms and display updates that work well with large databases, both in theory and in practice.

The Bead visualization system employs a fast algorithm for laying out high-dimensional data in a low-dimensional space, and a number of features added to 3D visualizations to improve imageability. We describe recent work on both aspects of the system, in particular a generalization of the data types laid out and the implementation of imageability features in a 2D visualization tool. The variety of data analyzed in a financial institution such as UBS, and the ubiquity of spreadsheets as a medium for analysis, led us to extend our layout tools to handle data in a generic spreadsheet format. We describe the metrics of similarity used for this data type, and give examples of layouts of sets of records of financial trades. Conservatism and scepticism with regard to 3D visualization, along with the lack of functionality of widely available 3D web browsers, led to the development of a 2D visualization tool with refinements of a number of our imageability features.