IEEE VIS Publication Dataset

Maximum projection is a volume rendering technique that, for each pixel, finds the maximum intensity along a projector. For certain important classes of data, this is an approximation to summation rendering which produces superior visualizations. We show how maximum projection rendering with additional depth cues can be implemented using simple affine transformations in object space. This technique can be used together with 3D graphics libraries and standard graphics hardware, thus allowing interactive manipulations of the volume data. The algorithm presented allows for a wide range of tradeoffs between interactivity and image quality

Visual realism is necessary for many virtual reality applications. In order to convince the user that the virtual environment is real, the scene presented should faithfully model the expected actual environment. A highly accurate, fully modeled, interactive environment is thus seen as ÔÇ£virtually realÔÇØ. The paper addresses the problem of interactive visual realism and discusses a possible solution: a hybrid rendering paradigm that ties distributed graphics hardware and ray tracing systems together for use in interactive, high visual realism applications. This new paradigm is examined in the context of a working rendering system. This system is capable of producing images of higher fidelity than possible through the use of graphics hardware alone, able both to render images at speeds useful for interactive systems and to progressively refine static, high quality snapshots

This paper describes an approach for interactive visualization of mixed scalar and vector fields, in which vector icons are generated from pre-voxelized icon templates and volume-rendered together with the volumetric scalar data. This approach displays simultaneously the global structure of the scalar field and the detailed features of the vector field. Interactive visualization is achieved with incremental image update, by re-rendering only a small portion of the image wherever and whenever a change occurs. This technique supports a set of interactive visualization tools, including change of vector field visualization parameters, real-time animation of vector icons advected within the scalar field, a zooming lens, and a local probe

A scalar volume V={(x,f(x))|x∈R} is described by a function f(x) defined over some region R of the three dimensional space. The paper presents a simple technique for rendering interval sets of the form Ig(a,b)={(x,f(x))|a⩽g(x)⩽b}, where a and b are either real numbers of infinities. We describe an algorithm for triangulating interval sets as α shapes, which can be accurately and efficiently rendered as surfaces or semi transparent clouds. On the theoretical side, interval sets provide an unified approach to isosurface extraction and direct volume rendering. On the practical side, interval sets add flexibility to scalar volume visualization-we may choose to, for example, have an interactive, high quality display of the volume surrounding or “inside” an isosurface when such display for the entire volume is too expensive to produce.

Proposes as a generalization of isosurfaces, the `interval volume', which is a new type of geometric model representing 3D subvolumes with field values belonging to a closed interval. A dominant surface fitting algorithm called `marching cubes' is extended to obtain a solid fitting algorithm, which extracts from a given volumetric dataset a high-resolution polyhedral solid data structure of the interval volume. Rendering methods for the interval volume and principal related operations are also presented. The effectiveness of this approach is illustrated with 4D simulated data from atomic collision research

Navigation in computer generated information spaces may be difficult, resulting in users getting ÔÇ£lost in hyperspaceÔÇØ. This work aims to build on research from the area of city planning to try to solve this problem. We introduce the concepts of legibility and cognitive maps and the five features of urban landscape with which they are associated. Following this will be descriptions of techniques and algorithms which we have developed to allow these features to be introduced to three dimensional spaces for information visualisation. Next we describe a specific application of these techniques in the visualisation of the World Wide Web and conclude with a look at future development of the system

The National Library of Medicine is creating a digital atlas of the human body. This project, called the Visible Human, has already produced computed tomography, magnetic resonance imaging and physical cross-sections of a human male cadaver. This paper describes a methodology and results for extracting surfaces from the Visible Male's CT data. We use surface connectivity and isosurface extraction techniques to create polygonal models of the skin, bone, muscle and bowels. We also report early experiments with the physical cross-sections

Splatting is an object space direct volume rendering algorithm that produces images of high quality, but is computationally expensive like many other volume rendering algorithms. The paper presents a new technique that enhances the speed of splatting without trading off image quality. This new method reduces rendering time by employing a simple indexing mechanism which allows to visit and splat only the voxels of interest. It is shown that this algorithm is suitable for the dynamic situation in which viewing parameters and opacity transfer functions change interactively. We report experimental results on several test data sets of useful site and complexity, and discuss the cost/benefit trade off of our method

An efficient algorithm is presented for computing particle paths, streak lines and time lines in time-dependent flows with moving curvilinear grids. The integration, velocity interpolation, and step size control are all performed in physical space which avoids the need to transform the velocity field into computational space. This leads to higher accuracy because there are no Jacobian matrix approximations, and expensive matrix inversions are eliminated. Integration accuracy is maintained using an adaptive step size control scheme which is regulated by the path line curvature. The problem of point location and interpolation in physical space is simplified by decomposing hexahedral cells into tetrahedral cells. This enables the point location to be done analytically and substantially faster than with a Newton-Raphson iterative method. Results presented show this algorithm is up to six times faster than particle tracers which operate on hexahedral cells, and produces almost identical traces

A general framework for visualization of statistical properties of high-dimensional pattern samples and the related computational steps are introduced. These procedures are exemplified on applications in anthropometrical research (shape information in faces) but can be easily generalized to various other morphometrical questions and data sets with pattern structure, e.g., data stemming from sensor arrays. Presently, the visualization techniques illustrated concentrate on (higher) moments of first order. It is suggested, how moments of second order can be visualized by animations and how this approach can be used in the context of comparative visualization

As part of an inter-disciplinary effort, we are visually exploring a current problem in philosophical logic related to information processing. Given a set of inconsistent sentences or inputs, a processor cannot unambiguously infer any specific consequence. Traces represent subsets of possible consequences which can be inferred classically from partitions of the set of inputs. We are interested in the relationship between a given set of Boolean inputs and its respective trace(s). We have developed a visualization paradigm which allows us to view and explore this relationship effectively

Invariant tori are examples of invariant manifolds in dynamical systems. Usual tools in dynamical systems such as analysis and numerical simulations alone are often not sufficient to understand the complicated mechanisms that cause changes in these manifolds. Computer-graphical visualization is a natural and powerful addition to these tools used for the qualitative study of dynamical systems, especially for the study of invariant manifolds. The dynamics of two linearly coupled oscillators is the focus of this case study. With little or no coupling between the oscillators, an invariant torus is present but it breaks down for strong coupling. Visualization has been employed to gain a qualitative understanding of this breakdown process. The visualization has allowed key features of the tori to be recognized, and it has proven to be indispensable in developing and testing hypotheses about the tori

An important goal of visualization technology is to support the exploration and analysis of very large amounts of data. In this paper, we propose a new visualization technique called a `recursive pattern', which has been developed for visualizing large amounts of multidimensional data. The technique is based on a generic recursive scheme which generalizes a wide range of pixel-oriented arrangements for displaying large data sets. By instantiating the technique with adequate data- and application-dependent parameters, the user may greatly influence the structure of the resulting visualizations. Since the technique uses one pixel for presenting each data value, the amount of data which can be displayed is only limited by the resolution of current display technology and by the limitations of human perceptibility. Beside describing the basic idea of the `recursive pattern' technique, we provide several examples of useful parameter settings for the various recursion levels. We further show that our `recursive pattern' technique is particularly advantageous for the large class of data sets which have a natural order according to one dimension (e.g. time series data). We demonstrate the usefulness of our technique by using a stock market application

Proposes an interactive method for exploring topological spaces based on the natural local geometry of the space. Examples of spaces appropriate for this visualization approach occur in abundance in mathematical visualization, surface and volume visualization problems, and scientific applications such as general relativity. Our approach is based on using a controller to choose a direction in which to ÔÇ£walkÔÇØ a manifold along a local geodesic path. The method automatically generates orientation changes that produce a maximal viewable region with each step of the walk. The proposed interaction framework has many natural properties to help the user develop a useful cognitive map of a space and is well-suited to haptic interfaces that may be incorporated into desktop virtual reality systems

The paper presents a splatting algorithm for volume rendering of curvilinear grids. A stochastic sampling technique called Poisson sphere/ellipsoid sampling is employed to adaptively resample a curvilinear grid with a set of randomly distributed points whose energy support extents are well approximated by spheres and ellipsoids. Filter kernels corresponding to these spheres and ellipsoids are used to generate the volume rendered image of the curvilinear grid with a conventional footprint evaluation algorithm. Experimental results show that our approach can be regarded as an alternative to existing fast volume rendering techniques of curvilinear grids

Diagrams are data representations that convey information predominantly through combinations of graphical elements rather than through other channels such as text or interaction. We have implemented a prototype called AVE (Automatic Visualization Environment) that generates diagrams automatically based on a generative theory of diagram design. According to this theory, diagrams are constructed based on the data to be visualized rather than by selection from a predefined set of diagrams. This approach can be applied to knowledge represented by semantic networks. We give a brief introduction to the underlying theory, then describe the implementation and finally discuss strategies for extending the algorithm

Presents an algorithm that accelerates the extraction of iso-surfaces from unstructured grids by avoiding the traversal of the entire set of cells in the volume. The algorithm consists of a sweep algorithm and a data decomposition scheme. The sweep algorithm incrementally locates intersected elements, and the data decomposition scheme restricts the algorithm's worst-case performance. For data sets consisting of hundreds of thousands of elements, our algorithm can reduce the cell traversal time by more than 90% over the naive iso-surface extraction algorithm, thus facilitating interactive probing of scalar fields for large-scale problems on unstructured three-dimensional grids

Presents a method for constructing tensor product Bezier surfaces from contour (cross-section) data. Minimal area triangulations are used to guide the surface construction, and the final surface reflects the optimality of the triangulation. The resulting surface differs from the initial triangulation in two important ways: it is smooth (as opposed to the piecewise planar triangulation), and it is in tensor product form (as opposed to the irregular triangular mesh). The surface reconstruction is efficient because we do not require an exact minimal surface. The triangulations are used as strong hints, but no more than that. The method requires the computation of both open and closed isoparametric curves of the surface, using triangulations as a guide. These isoparametric curves form a tensor product Bezier surface. We show how to control sampling density by filling and pruning isoparametric curves, for accuracy and economy. A rectangular grid of points is produced that is compatible with the expected format for a tensor product surface interpolation, so that a host of well-supported methods are available to generate and manipulate the surface

Presents a simple, robust and practical method for object simplification for applications where gradual elimination of high-frequency details is desired. This is accomplished by sampling and low-pass filtering the object into multi-resolution volume buffers and applying the marching cubes algorithm to generate a multi-resolution triangle-mesh hierarchy. Our method simplifies the genus of objects and can also help existing object simplification algorithms achieve better results. At each level of detail, a multi-layered mesh can be used for an optional and efficient antialiased rendering

Flow volumes are extended for use in unsteady (time-dependent) flows. The resulting unsteady flow volumes are the 3D analogs of streaklines. There are few examples where methods other than particle tracing have been used to visualize time-varying flows. Since particle paths can become convoluted in time, there are additional considerations to be made when extending any visualization technique to unsteady flows. We present some solutions to the problems which occur in subdivision, rendering and system design. We apply the unsteady flow volumes to a variety of field types, including moving multi-zoned curvilinear grids