IEEE VIS Publication Dataset

In this case study, we explore techniques for the purpose of visualizing isolated flow structures in time-dependent data. Our primary industrial application is the visualization of the vortex rope, a rotating helical structure which builds up in the draft tube of a water turbine. The vortex rope can be characterized by high values of normalized helicity, which is a scalar field derived from the given CFD velocity data. In two related applications, the goal is to visualize the cavitation regions near the runner blades of a Kaplan turbine and a water pump, respectively. Again, the flow structure of interest can be defined by a scalar field, namely by low pressure values. We propose a particle seeding scheme based on quasi-random numbers, which minimizes visual artifacts such as clusters or patterns. By constraining the visualization to a region of interest, occlusion problems are reduced and storage efficiency is gained.

In this paper, we address the problem of automatic camera positioning and automatic camera path generation in the context of historical data visualization. After short description of the given data, we elaborate on the constraints for the positioning of a virtual camera in such a way that not only the projected area is maximized, but also the depth of the displayed scene. This is especially important when displaying terrain models, which do not provide good 3D impression when only the projected area is maximized. Based on this concept, we present a method for computing an optimal camera position for each instant of time. Since the explored data are not static, but change depending on the explored scene time, we also discuss a method for animation generation. In order to avoid sudden changes of the camera position, when the previous method is applied for each frame (point in time), we introduce pseudo-events in time, which expand the bounding box defined by the currently active events of interest. In particular, this technique allows events happening in a future point in time to be taken into account such that when this time becomes current, all events of interest are already within the current viewing frustum of the camera.

Weather radars can measure the backscatter from rain drops in the atmosphere. A complete radar scan provides three-dimensional precipitation information. For the understanding of the underlying atmospheric processes interactive visualization of these data sets is necessary. This is a challenging task due to the size, structure and required context of the data. In this case study, a multiresolution approach for real-time simultaneous visualization of radar measurements together with the corresponding terrain data is illustrated.

Active stereo has been used by engineers and industrial designers for several years to enhance the perception of computer generated three-dimensional images. Unfortunately, active stereo requires specialized hardware. Therefore, as ubiquitous computing and teleworking gain importance, using active stereo becomes a problem. The goal of this case study is to examine the concept of a generic library for polychromatic passive stereo to make stereo vision available everywhere.

The current state of the art in visualization research places strong emphasis on different techniques to derive insight from disparate types of data. However, little work has investigated the visualization process itself. The information content of the visualization process - the results, history, and relationships between those results - is addressed by this work. A characterization of the visualization process is discussed, leading to a general model of the visualization exploration process. The model, based upon a new parameter derivation calculus, can be used for automated reporting, analysis, or visualized directly. An XML-based language for expressing visualization sessions using the model is also described. These sessions can then be shared and reused by collaborators. The model, along with the XML representation, provides an effective means to utilize information within the visualization process to further data exploration.

We present a new multiphase method for efficiently simplifying polygonal surface models of arbitrary size. It operates by combining an initial out-of-core uniform clustering phase with a subsequent in-core iterative edge contraction phase. These two phases are both driven by quadric error metrics, and quadrics are used to pass information about the original surface between phases. The result is a method that produces approximations of a quality comparable to quadric-based iterative edge contraction, but at a fraction of the cost in terms of running time and memory consumption.

Many direct volume rendering algorithms have been proposed during the last decade to render 2563 voxels interactively. However a lot of limitations are inherent to all of them, like low-quality images, a small viewport size or a fixed classification. In contrast, interactive high quality algorithms are still a challenge nowadays. We introduce here an efficient and accurate technique called object-order ray-casting that can achieve up to 10 fps on current workstations. Like usual ray-casting, colors and opacities are evenly sampled along the ray, but now within a new object-order algorithm. Thus, it allows to combine the main advantages of both worlds in term of speed and quality. We also describe an efficient hidden volume removal technique to compensate for the loss of early ray termination.

The analysis of multidimensional functions is important in many engineering disciplines, and poses a major problem as the number of dimensions increases. Previous visualization approaches focus on representing three or fewer dimensions at a time. This paper presents a new focus+context visualization that provides an integrated overview of an entire multidimensional function space, with uniform treatment of all dimensions. The overview is displayed with respect to a user-controlled polar focal point in the function's parameter space. Function value patterns are viewed along rays that emanate from the focal point in all directions in the parameter space, and represented radially around the focal point in the visualization. Data near the focal point receives proportionally more screen space than distant data. This approach scales smoothly from two dimensions to 10-20, with a 1000 pixel range on each dimension.

We present some new methods for computing estimates of normal vectors at the vertices of a triangular mesh surface approximation to an isosurface which has been computed by the marching cube algorithm. These estimates are required for the smooth rendering of triangular mesh surfaces. The conventional method of computing estimates based upon divided difference approximations of the gradient can lead to poor estimates in some applications. This is particularly true for isosurfaces obtained from a field function, which is defined only for values near to the isosurface. We describe some efficient methods for computing the topology of the triangular mesh surface, which is used for obtaining local estimates of the normals. In addition, a new, one pass, approach for these types of applications is described and compared to existing methods.

This paper presents a new technique for visualizing large, complex collections of data. The size and dimensionality of these datasets make them challenging to display in an effective manner. The images must show the global structure of spatial relationships within the dataset, yet at the same time accurately represent the local detail of each data element being visualized. We propose combining ideas from information and scientific visualization together with a navigation assistant, a software system designed to help users identify and explore areas of interest within their data. The assistant locates data elements of potential importance to the user, clusters them into spatial regions, and builds underlying graph structures to connect the regions and the elements they contain. Graph traversal algorithms, constraint-based viewpoint construction, and intelligent camera planning techniques can then be used to design animated tours of these regions. In this way, the navigation assistant can help users to explore any of the areas of interest within their data. We conclude by demonstrating how our assistant is being used to visualize a multidimensional weather dataset.

In this paper we introduce a new and simple algorithm to compress isosurface data. This is the data extracted by isosurface algorithms from scalar functions defined on volume grids, and used to generate polygon meshes or alternative representations. In this algorithm the mesh connectivity and a substantial proportion of the geometric information are encoded to a fraction of a bit per marching cubes vertex with a context based arithmetic coder closely related to the JBIG binary image compression standard. The remaining optional geometric information that specifies the location of each marching cubes vertex more precisely along its supporting intersecting grid edge, is efficiently encoded in scan-order with the same mechanism. Vertex normals can optionally be computed as normalized gradient vectors by the encoder and included in the bitstream after quantization and entropy encoding, or computed by the decoder in a postprocessing smoothing step. These choices are determined by trade-offs associated with an in-core vs. out-of-core decoder structure. The main features of our algorithm are its extreme simplicity and high compression rates.

This paper describes BM3D: a method for the analysis of motion in time dependent volume data. From a sequence of volume data sets a sequence of vector data sets representing the movement of the data is computed. A block matching technique is used for the reconstruction of data movement. The derived vector field can be used for the visualization of time dependent volume data. The method is illustrated in two applications.

Many computer graphics operations, such as texture mapping, 3D painting, remeshing, mesh compression, and digital geometry processing, require finding a low-distortion parameterization for irregular connectivity triangulations of arbitrary genus 2-manifolds. This paper presents a simple and fast method for computing parameterizations with strictly bounded distortion. The new method operates by flattening the mesh onto a region of the 2D plane. To comply with the distortion bound, the mesh is automatically cut and partitioned on-the-fly. The method guarantees avoiding global and local self-intersections, while attempting to minimize the total length of the introduced seams. To our knowledge, this is the first method to compute the mesh partitioning and the parameterization simultaneously and entirely automatically, while providing guaranteed distortion bounds. Our results on a variety of objects demonstrate that the method is fast enough to work with large complex irregular meshes in interactive applications.

Visualization is required for the effective utilization of data from a weather simulation. Appropriate mapping of user goals to the design of pictorial content has been useful in the development of interactive applications with sufficient bandwidth for timely access to the model data. When remote access to the model visualizations is required the limited bandwidth becomes the primary bottleneck. To help address these problems, visualizations are presented on a Web page as a meta-representation of the model output and serve as an index to simplify finding other visualizations of relevance. To provide consistency with extant interactive products and to leverage their cost of development, the aforementioned applications are adapted to automatically populate a Web site with images and interactions for an operational weather forecasting system.

For most of the time, we enjoy and appreciate music performances as they are. Once we try to understand the performance not in subjective terms but in an objective way and share it with other people, visualizing the performance parameters is indispensable. In this paper, a figure for visualizing performance expressions is described. This figure helps people understand the cause and position of the performance expression as it has expressive cues, which coincide with the cognitive meaning of musical performance, and not by using only MIDI parameter values. The differences we hear between performances are clarified by visualized figures.

With the completion of the human genome sequence, and with the proliferation of genome-related annotation data, the need for scalable and more intuitive means for analysis becomes critical, At Variagenics and Small Design Firm, we have addressed this problem with a coherent three-dimensional space in which all data can be seen in a single context. This tool aids in integrating information at vastly divergent scales while maintaining accurate spatial and size relationships. Our visualization was successful in communicating to project teams with diverse backgrounds the magnitude and biological implication of genetic variation.

Line Integral Convolution (LIC) is a promising method for visualizing 2D dense flow fields. Direct extensions of the LIC method to 3D have not been considered very effective, because optical integration in viewing directions tends to spoil the coherent structures along 3D local streamlines. In our previous reports, we have proposed a selective approach to volume rendering of LIC solid texture using 3D significance map (S-map), derived from the characteristics of flow structures, and a specific illumination model for 3D streamlines. In this paper, we take full advantage of scalar volume rendering hardware, such as VolumePro, to realize a realtime 3D flow field visualization environment with the LIC volume rendering method.

Adaptive mesh refinement (AMR) is a popular computational simulation technique used in various scientific and engineering fields. Although AMR data is organized in a hierarchical multi-resolution data structure, the traditional volume visualization algorithms such as ray-casting and splatting cannot handle the form without converting it to a sophisticated data structure. In this paper, we present a hierarchical multi-resolution splatting technique using k-d trees and octrees for AMR data that is suitable for implementation on the latest consumer PC graphics hardware. We describe a graphical user interface to set transfer function and viewing/rendering parameters interactively. Experimental results obtained on a general purpose PC equipped with NVIDIA GeForce card are presented to demonstrate that the technique can interactively render AMR data (over 20 frames per second). Our scheme can easily be applied to parallel rendering of time-varying AMR data.

Internet connectivity is defined by a set of routing protocols which let the routers that comprise the Internet backbone choose the best route for a packet to reach its destination. One way to improve the security and performance of Internet is to routinely examine the routing data. In this case study, we show how interactive visualization of Border Gateway Protocol (BGP) data helps characterize routing behavior, identify weaknesses in connectivity which could potentially cripple the Internet, as well as detect and explain actual anomalous events.

As part of a larger effort exploring alternative display systems, Lawrence Livermore National Laboratory has installed systems in two offices that extend and update the previously described "Office of Real Soon Now" project to improve the value for visualization tasks. These new systems use higher resolution projectors driven by workstations that run Unix-based applications via Linux and support hardware-accelerated 3D graphics, even across the boundary between displays.