DevLan/vispubs huggingface dataset:
Scale-invariant volume rendering
Authors: Martin Kraus
Published at Vis, 2005

As standard volume rendering is based on an integral in physical space (or "coordinate space"), it is inherently dependent on the scaling of this space. Although this dependency is appropriate for the realistic rendering of semitransparent volumetric objects, it has several unpleasant consequences for volume visualization. In order to overcome these disadvantages, a new variant of the volume rendering integral is proposed, which is defined in data space instead of physical space. Apart from achieving scale invariance, this new method supports the rendering of isosurfaces of uniform opacity and color, independently of the local gradient or" the visualized scalar field. Moreover, it reveals certain structures in scalar fields even with constant transfer functions. Furthermore, it can be defined as the limit of infinitely many semitransparent isosurfaces, and is therefore based on an intuitive and at the same time precise definition. In addition to the discussion of these features of scale-invariant volume rendering, efficient adaptations of existing volume rendering algorithms and extensions for silhouette enhancement and local illumination by transmitted light are presented.
Sort-middle multi-projector immediate-mode rendering in Chromium
Authors: Jorge Luis Williams, Robert E. Hiromoto
Published at Vis, 2005

Traditionally, sort-middle is a technique that has been difficult to attain on clusters because of the tight coupling of geometry and rasterization processes on commodity graphics hardware. In this paper, we describe the implementation of a new sort-middle approach for performing immediate-mode rendering in Chromium. The Chromium Rendering System is used extensively to drive multi-projector displays on PC clusters with inexpensive commodity graphics components. By default, Chromium uses a sort-first approach to distribute rendering work to individual nodes in a PC cluster. While this sort-first approach works effectively in retained-mode rendering, it suffers from various network bottlenecks when rendering in immediate-mode. Current techniques avoid these bottlenecks by sorting vertex data as a pre-processing step and grouping vertices into specific bounding boxes, using Chromium's bounding box extension. These steps may be expensive, especially if the dataset is dynamic. In our approach, we utilize standard programmable graphics hardware and extend standard APIs to achieve a separation in the rendering pipeline. The pre-processing of vertex data or the grouping of vertices into bounding boxes are not required. Additionally, the amount of OpenGL state commands transmitted through the network are reduced. Our results indicate that the approach can attain twice the frame rates as compared to Chromium's sort-first approach when rendering in immediate-mode.
Statistically quantitative volume visualization
Authors: Joe Michael Kniss, Robert L. Van Uitert Jr., Abraham Stephens, Guo-Shi Li, Tolga Tasdizen, Charles D. Hansen
Published at Vis, 2005

Visualization users are increasingly in need of techniques for assessing quantitative uncertainty and error in the images produced. Statistical segmentation algorithms compute these quantitative results, yet volume rendering tools typically produce only qualitative imagery via transfer function-based classification. This paper presents a visualization technique that allows users to interactively explore the uncertainty, risk, and probabilistic decision of surface boundaries. Our approach makes it possible to directly visualize the combined "fuzzy" classification results from multiple segmentations by combining these data into a unified probabilistic data space. We represent this unified space, the combination of scalar volumes from numerous segmentations, using a novel graph-based dimensionality reduction scheme. The scheme both dramatically reduces the dataset size and is suitable for efficient, high quality, quantitative visualization. Lastly, we show that the statistical risk arising from overlapping segmentations is a robust measure for visualizing features and assigning optical properties.
Strategy for seeding 3D streamlines
Authors: Xiaohong Ye, David L. Kao, Alex T. Pang
Published at Vis, 2005

This paper presents a strategy for seeding streamlines in 3D flow fields. Its main goal is to capture the essential flow patterns and to provide sufficient coverage in the field while reducing clutter. First, critical points of the flow field are extracted to identify regions with important flow patterns that need to be presented. Different seeding templates are then used around the vicinity of the different critical points. Because there is significant variability in the flow pattern even for the same type of critical point, our template can change shape depending on how far the critical point is from transitioning into another type of critical point. To accomplish this, we introduce the /spl alpha/-/spl beta/ map of 3D critical points. Next, we use Poisson seeding to populate the empty regions. Finally, we filter the streamlines based on their geometric and spatial properties. Altogether, this multi-step strategy reduces clutter and yet captures the important 3D flow features.
Stream-processing points
Authors: Renato Pajarola
Published at Vis, 2005

With the growing size of captured 3D models it has become increasingly important to provide basic efficient processing methods for large unorganized raw surface-sample point data sets. In this paper we introduce a novel stream-based (and out-of-core) point processing framework. The proposed approach processes points in an orderly sequential way by sorting them and sweeping along a spatial dimension. The major advantages of this new concept are: (1) support of extensible and concatenate local operators called stream operators, (2) low main-memory usage and (3) applicability to process very large data sets out-of-core.
Streaming meshes
Authors: Martin Isenburg, Peter Lindstrom 0001
Published at Vis, 2005

Recent years have seen an immense increase in the complexity of geometric data sets. Today's gigabyte-sized polygon models can no longer be completely loaded into the main memory of common desktop PCs. Unfortunately, current mesh formats, which were designed years ago when meshes were orders of magnitudes smaller, do not account for this. Using such formats to store large meshes is inefficient and complicates all subsequent processing. We describe a streaming format for polygon meshes that is simple enough to replace current offline mesh formats and is more suitable for representing large data sets. Furthermore, it is an ideal input and output format for I/O-efficient out-of-core algorithms that process meshes in a streaming, possibly pipelined, fashion. This paper chiefly concerns the underlying theory and the practical aspects of creating and working with this new representation. In particular, we describe desirable qualities for streaming meshes and methods for converting meshes from a traditional to a streaming format. A central theme of this paper is the issue of coherent and compatible layouts of the mesh vertices and polygons. We present metrics and diagrams that characterize the coherence of a mesh layout and suggest appropriate strategies for improving its "streamability". To this end, we outline several out-of-core algorithms for reordering meshes with poor coherence, and present results for a menagerie of well known and generally incoherent surface meshes.
Surface reconstruction via contour metamorphosis: an Eulerian approach with Lagrangian particle tracking
Authors: Ola Nilsson, David E. Breen, Ken Museth
Published at Vis, 2005

We present a robust method for 3D reconstruction of closed surfaces from sparsely sampled parallel contours. A solution to this problem is especially important for medical segmentation, where manual contouring of 2D imaging scans is still extensively used. Our proposed method is based on a morphing process applied to neighboring contours that sweeps out a 3D surface. Our method is guaranteed to produce closed surfaces that exactly pass through the input contours, regardless of the topology of the reconstruction. Our general approach consecutively morphs between sets of input contours using an Eulerian formulation (i.e. fixed grid) augmented with Lagrangian particles (i.e. interface tracking). This is numerically accomplished by propagating the input contours as 2D level sets with carefully constructed continuous speed functions. Specifically this involves particle advection to estimate distances between the contours, monotonicity constrained spline interpolation to compute continuous speed functions without overshooting, and state-of-the-art numerical techniques for solving the level set equations. We demonstrate the robustness of our method on a variety of medical, topographic and synthetic data sets.
Teniae coli guided navigation and registration for virtual colonoscopy
Authors: Adam Huang, Dave Roy, Marek Franaszek, Ronald M. Summers
Published at Vis, 2005

We present a new method for guiding virtual colonoscopic navigation and registration by using teniae coli as anatomical landmarks. As most existing protocols require a patient to be scanned in both supine and prone positions to increase sensitivity in detecting colonic polyps, reference and registration between scans are necessary. However, the conventional centerline approach, generating only the longitudinal distance along the colon, lacks the necessary orientation information to synchronize the virtual navigation cameras in both scanned positions. In this paper we describe a semi-automatic method to detect teniae coli from a colonic surface model reconstructed from CT colonography. Teniae coli are three bands of longitudinal smooth muscle on the surface of the colon. They form a triple helix structure from the appendix to the sigmoid colon and are ideal references for virtual navigation. Our method was applied to 3 patients resulting in 6 data sets (supine and prone scans). The detected teniae coli matched well with our visual inspection. In addition, we demonstrate that polyps visible on both scans can be located and matched more efficiently with the aid of a teniae coli guided navigation implementation.
Texture-based visualization of uncertainty in flow fields
Authors: Ralf P. Botchen, Daniel Weiskopf, Thomas Ertl
Published at Vis, 2005

In this paper, we present two novel texture-based techniques to visualize uncertainty in time-dependent 2D flow fields. Both methods use semi-Lagrangian texture advection to show flow direction by streaklines and convey uncertainty by blurring these streaklines. The first approach applies a cross advection perpendicular to the flow direction. The second method employs isotropic diffusion that can be implemented by Gaussian filtering. Both methods are derived from a generic filtering process that is incorporated into the traditional texture advection pipeline. Our visualization methods allow for a continuous change of the density of flow representation by adapting the density of particle injection. All methods can be mapped to efficient GPU implementations. Therefore, the user can interactively control all important characteristics of the system like particle density, error influence, or dye injection to create meaningful illustrations of the underlying uncertainty. Even though there are many sources of uncertainties, we focus on uncertainty that occurs during data acquisition. We demonstrate the usefulness of our methods for the example of real-world fluid flow data measured with the particle image velocimetry (PIV) technique. Furthermore, we compare these techniques with an adapted multi-frequency noise approach.
The application of GPU particle tracing to diffusion tensor field visualization
Authors: Polina Kondratieva, Jens H. Krüger, Rüdiger Westermann
Published at Vis, 2005

In this paper we introduce GPU particle tracing for the visualization of 3D diffusion tensor fields. For about half a million particles, reconstruction of diffusion directions from the tensor field, time integration and rendering can be done at interactive rates. Different visualization options like oriented particles of diffusion-dependent shape, stream lines or stream tubes facilitate the use of particle tracing for diffusion tensor visualization. The proposed methods provide efficient and intuitive means to show the dynamics in diffusion tensor fields, and they accommodate the exploration of the diffusion properties of biological tissue.
The magic volume lens: an interactive focus+context technique for volume rendering
Authors: Lujin Wang, Ye Zhao 0004, Klaus Mueller 0001, Arie E. Kaufman
Published at Vis, 2005

The size and resolution of volume datasets in science and medicine are increasing at a rate much greater than the resolution of the screens used to view them. This limits the amount of data that can be viewed simultaneously, potentially leading to a loss of overall context of the data when the user views or zooms into a particular area of interest. We propose a focus+context framework that uses various standard and advanced magnification lens rendering techniques to magnify the features of interest, while compressing the remaining volume regions without clipping them away completely. Some of these lenses can be interactively configured by the user to specify the desired magnification patterns, while others are feature-adaptive. All our lenses are accelerated on the GPU. They allow the user to interactively manage the available screen area, dedicating more area to the more resolution-important features.
The software interface to the 3D-force microscope
Authors: David Marshburn, Chris Weigle, Benjamin G. Wilde, Russell M. Taylor II, Kalpit Desai, J. K. Fisher, Jeremy Cribb, E. Timothy O'Brien, Richard Superfine
Published at Vis, 2005

We have developed a real-time experiment-control and data-display system for a novel microscope, the 3D-force microscope (3DFM), which is designed for nanometer-scale and nanoNewton-force biophysical experiments. The 3DFM software suite synthesizes the several data sources from the 3DFM into a coherent view and provides control over data collection and specimen manipulation. Herein, we describe the system architecture designed to handle the several feedback loops and data flows present in the microscope and its control system. We describe the visualization techniques used in the 3DFM software suite, where used, and on which types of data. We present feedback from our scientist-users regarding the usefulness of these techniques, and we also present lessons learned from our successive implementations.
The value of visualization
Authors: Jarke J. van Wijk
Published at Vis, 2005

The field of visualization is getting mature. Many problems have been solved, and new directions are sought for. In order to make good choices, an understanding of the purpose and meaning of visualization is needed. Especially, it would be nice if we could assess what a good visualization is. In this paper an attempt is made to determine the value of visualization. A technological viewpoint is adopted, where the value of visualization is measured based on effectiveness and efficiency. An economic model of visualization is presented, and benefits and costs are established. Next, consequences (brand limitations of visualization are discussed (including the use of alternative methods, high initial costs, subjective/less, and the role of interaction), as well as examples of the use of the model for the judgement of existing classes of methods and understanding why they are or are not used in practice. Furthermore, two alternative views on visualization are presented and discussed: viewing visualization as an art or as a scientific discipline. Implications and future directions are identified.
The visible radio: process visualization of a software-defined radio
Authors: Matthew Hall, Alex Betts, Donna J. Cox, David Pointer, Volodymyr V. Kindratenko
Published at Vis, 2005

In this case study, a data-oriented approach is used to visualize a complex digital signal processing pipeline. The pipeline implements a frequency modulated (FM) software-defined radio (SDR). SDR is an emerging technology where portions of the radio hardware, such as filtering and modulation, are replaced by software components. We discuss how an SDR implementation is instrumented to illustrate the processes involved in FM transmission and reception. By using audio-encoded images, we illustrate the processes involved in radio, such as how filters are used to reduce noise, the nature of a carrier wave, and how frequency modulation acts on a signal. The visualization approach used in this work is very effective in demonstrating advanced topics in digital signal processing and is a useful tool for experimenting with the software radio design.
Topological structures of 3D tensor fields
Authors: Xiaoqiang Zheng, Beresford N. Parlett, Alex T. Pang
Published at Vis, 2005

Tensor topology is useful in providing a simplified and yet detailed representation of a tensor field. Recently the field of 3D tensor topology is advanced by the discovery that degenerate tensors usually form lines in their most basic configurations. These lines form the backbone for further topological analysis. A number of ways for extracting and tracing the degenerate tensor lines have also been proposed. In this paper, we complete the previous work by studying the behavior and extracting the separating surfaces emanating from these degenerate lines. First, we show that analysis of eigenvectors around a 3D degenerate tensor can be reduced to 2D. That is, in most instances, the 3D separating surfaces are just the trajectory of the individual 2D separatrices which includes trisectors and wedges. But the proof is by no means trivial since it is closely related to perturbation theory around a pair of singular slate. Such analysis naturally breaks down at the tangential points where the degenerate lines pass through the plane spanned by the eigenvectors associated with the repeated eigenvalues. Second, we show that the separatrices along a degenerate line may switch types (e.g. trisectors to wedges) exactly at the points where the eigenplane is tangential to the degenerate curve. This property leads to interesting and yet complicated configuration of surfaces around such transition points. Finally, we apply the technique to several common data sets to verify its correctness.
Topology-based simplification for feature extraction from 3D scalar fields
Authors: Attila Gyulassy, Vijay Natarajan, Valerio Pascucci, Peer-Timo Bremer, Bernd Hamann
Published at Vis, 2005

In this paper, we present a topological approach for simplifying continuous functions defined on volumetric domains. We introduce two atomic operations that remove pairs of critical points of the function and design a combinatorial algorithm that simplifies the Morse-Smale complex by repeated application of these operations. The Morse-Smale complex is a topological data structure that provides a compact representation of gradient flow between critical points of a function. Critical points paired by the Morse-Smale complex identify topological features and their importance. The simplification procedure leaves important critical points untouched, and is therefore useful for extracting desirable features. We also present a visualization of the simplified topology.
Topology-driven surface mappings with robust feature alignment
Authors: Christopher Carner, Miao Jin, Xianfeng Gu, Hong Qin
Published at Vis, 2005

Topological concepts and techniques have been broadly applied in computer graphics and geometric modeling. However, the homotopy type of a mapping between two surfaces has not been addressed before. In this paper, we present a novel solution to the problem of computing continuous maps with different homotopy types between two arbitrary triangle meshes with the same topology. Inspired by the rich theory of topology as well as the existing body of work on surface mapping, our newly-developed mapping techniques are both fundamental and unique, offering many attractive advantages. First, our method allows the user to change the homotopy type or global structure of the mapping with minimal intervention. Moreover, to locally affect shape correspondence, we articulate a new technique that robustly satisfies hard feature constraints, without the use of heuristics to ensure validity. In addition to acting as a useful tool for computer graphics applications, our method can be used as a rigorous and practical mechanism for the visualization of abstract topological concepts such as homotopy type of surface mappings, homology basis, fundamental domain, and universal covering space. At the core of our algorithm is a procedure for computing the canonical homology basis and using it as a common cut graph for any surface with the same topology. We demonstrate our results by applying our algorithm to shape morphing in this paper.
Understanding visualization through spatial ability differences
Authors: Maria C. Velez, Deborah Silver, Marilyn Tremaine
Published at Vis, 2005

Little is known about the cognitive abilities which influence the comprehension of scientific and information visualizations and what properties of the visualization affect comprehension. Our goal in this paper is to understand what makes visualizations difficult. We address this goal by examining the spatial ability differences in a diverse population selected for spatial ability variance. For example, how is, spatial ability related to visualization comprehension? What makes a particular visualization difficult or time intensive for specific groups of subjects? In this paper, we present the results of an experiment designed to answer these questions. Fifty-six subjects were tested on a basic visualization task and given standard paper tests of spatial abilities. An equal number of males and females were recruited in this study in order to increase spatial ability variance. Our results show that high spatial ability is correlated with accuracy on our three-dimensional visualization test, but not with time. High spatial ability subjects also had less difficulty with object complexity and the hidden properties of an object.
View selection for volume rendering
Authors: Udeepta Bordoloi, Han-Wei Shen
Published at Vis, 2005

In a visualization of a three-dimensional dataset, the insights gained are dependent on what is occluded and what is not. Suggestion of interesting viewpoints can improve both the speed and efficiency of data understanding. This paper presents a view selection method designed for volume rendering. It can be used to find informative views for a given scene, or to find a minimal set of representative views which capture the entire scene. It becomes particularly useful when the visualization process is non-interactive - for example, when visualizing large datasets or time-varying sequences. We introduce a viewpoint "goodness" measure based on the formulation of entropy from information theory. The measure takes into account the transfer function, the data distribution and the visibility of the voxels. Combined with viewpoint properties like view-likelihood and view-stability, this technique can be used as a guide, which suggests "interesting" viewpoints for further exploration. Domain knowledge is incorporated into the algorithm via an importance transfer function or volume. This allows users to obtain view selection behaviors tailored to their specific situations. We generate a view space partitioning, and select one representative view for each partition. Together, this set of views encapsulates the "interesting" and distinct views of the data. Viewpoints in this set can be used as starting points for interactive exploration of the data, thus reducing the human effort in visualization. In non-interactive situations, such a set can be used as a representative visualization of the dataset from all directions.