DevLan/vispubs huggingface dataset:
LightKit: a lighting system for effective visualization
Authors: Michael Halle, Jeanette C. Meng
Published at Vis, 2003

LightKit is a system for lighting three-dimensional synthetic scenes. LightKit simplifies the task of producing visually pleasing, easily interpretable images for visualization while making it harder to produce results where the scene illumination distracts from the visualization process. LightKit is based on lighting designs developed by artists and photographers and shown in previous studies to enhance shape perception. A key light provides natural overhead illumination of the scene, augmented by fill, head, and back lights. By default, lights are attached to a normalized, subject-centric, camera-relative coordinate frame to ensure consistent lighting independent of camera location or orientation. This system allows all lights to be positioned by specifying just six parameters. The intensity of each light is specified as a ratio to the key light intensity, allowing the scene's brightness to be adjusted using a single parameter. The color of each light is specified by a single normalized color parameter called warmth that is based on color temperature of natural sources. LightKit's default values for light position, intensity, and color are chosen to produce good results for a variety of scenes. LightKit is designed to work with both hardware graphics systems and, potentially, higher quality off-line rendering systems. We provide examples of images created using a LightKit implementation within the VTK visualization toolkit software framework.
MC*: star functions for marching cubes
Authors: Gregory M. Nielson
Published at Vis, 2003

We describe a modification of the widely used marching cubes method that leads to the useful property that the resulting isosurfaces are locally single valued functions. This implies that conventional interpolation and approximation methods can be used to locally represent the surface. These representations can be used for computing approximations for local surface properties. We utilize this possibility in order to develop algorithms for locally approximating Gaussian and mean curvature, methods for constrained smoothing of isosurface, and techniques for the parameterization of isosurfaces.
Mental registration of 2D and 3D visualizations (an empirical study)
Authors: Melanie Tory
Published at Vis, 2003

2D and 3D views are used together in many visualization domains, such as medical imaging, flow visualization, oceanographic visualization, and computer aided design (CAD). Combining these views into one display can be done by: (1) orientation icon (i.e., separate windows), (2) in-place methods (e.g., clip and cutting planes), and (3) a new method called ExoVis. How 2D and 3D views are displayed affects ease of mental registration (understanding the spatial relationship between views), an important factor influencing user performance. This paper compares the above methods in terms of their ability to support mental registration. Empirical results show that mental registration is significantly easier with in-place displays than with ExoVis, and significantly easier with ExoVis than with orientation icons. Different mental transformation strategies can explain this result. The results suggest that ExoVis may be a better alternative to orientation icons when in-place displays are not appropriate (e.g., when in-place methods hide data or cut the 3D view into several pieces).
Monte Carlo volume rendering
Authors: Balázs Csébfalvi, László Szirmay-Kalos
Published at Vis, 2003

In this paper a novel volume-rendering technique based on Monte Carlo integration is presented. As a result of a preprocessing, a point cloud of random samples is generated using a normalized continuous reconstruction of the volume as a probability density function. This point cloud is projected onto the image plane, and to each pixel an intensity value is assigned which is proportional to the number of samples projected onto the corresponding pixel area. In such a way a simulated X-ray image of the volume can be obtained. Theoretically, for a fixed image resolution, there exists an M number of samples such that the average standard deviation of the estimated pixel intensities us under the level of quantization error regardless of the number of voxels. Therefore Monte Carlo Volume Rendering (MCVR) is mainly proposed to efficiently visualize large volume data sets. Furthermore, network applications are also supported, since the trade-off between image quality and interactivity can be adapted to the bandwidth of the client/server connection by using progressive refinement.
Out-of-core isosurface extraction of time-varying fields over irregular grids
Authors: Yi-Jen Chiang
Published at Vis, 2003

In this paper, we propose a novel out-of-core isosurface extraction technique for large time-varying fields over irregular grids. We employ our meta-cell technique to explore the spatial coherence of the data, and our time tree algorithm to consider the temporal coherence as well. Our one-time preprocessing phase first partitions the dataset into meta-cells that cluster spatially neighboring cells together and are stored in disk. We then build a time tree to index the meta-cells for fast isosurface extraction. The time tree takes advantage of the temporal coherence among the scalar values at different time steps, and uses BBIO trees as secondary structures, which are stored in disk and support I/O-optimal interval searches. The time tree algorithm employs a novel meta-interval collapsing scheme and the buffer technique, to take care of the temporal coherence in an I/O-efficient way. We further make the time tree cache-oblivious, so that searching on it automatically performs optimal number of block transfers between any two consecutive levels of memory hierarchy (such as between cache and main memory and between main memory and disk) simultaneously. At run-time, we perform optimal cache-oblivious searches in the time tree, together with I/O-optimal searches in the BBIO trees, to read the active meta-cells from disk and generate the queried isosurface efficiently. The experiments demonstrate the effectiveness of our new technique. In particular, compared with the query-optimal main-memory algorithm by Cignoni et al. (1997) (extended for time-varying fields) when there is not enough main memory, our technique can speed up the isosurface queries from more than 18 hours to less than 4 minutes.
Piecewise C¹ continuous surface reconstruction of noisy point clouds via local implicit quadric regression
Authors: Hui Xie 0001, Jianning Wang, Jing Hua 0001, Hong Qin, Arie E. Kaufman
Published at Vis, 2003

This paper addresses the problem of surface reconstruction of highly noisy point clouds. The surfaces to be reconstructed are assumed to be 2-manifolds of piecewise C/sup 1/ continuity, with isolated small irregular regions of high curvature, sophisticated local topology or abrupt burst of noise. At each sample point, a quadric field is locally fitted via a modified moving least squares method. These locally fitted quadric fields are then blended together to produce a pseudo-signed distance field using Shepard's method. We introduce a prioritized front growing scheme in the process of local quadrics fitting. Flatter surface areas tend to grow faster. The already fitted regions will subsequently guide the fitting of those irregular regions in their neighborhood.
Planet-sized batched dynamic adaptive meshes (P-BDAM)
Authors: Paolo Cignoni, Fabio Ganovelli, Enrico Gobbetti, Fabio Marton, Federico Ponchio, Roberto Scopigno
Published at Vis, 2003

We describe an efficient technique for out-of-core management and interactive rendering of planet sized textured terrain surfaces. The technique, called planet-sized batched dynamic adaptive meshes (P-BDAM), extends the BDAM approach by using as basic primitive a general triangulation of points on a displaced triangle. The proposed framework introduces several advances with respect to the state of the art: thanks to a batched host-to-graphics communication model, we outperform current adaptive tessellation solutions in terms of rendering speed; we guarantee overall geometric continuity, exploiting programmable graphics hardware to cope with the accuracy issues introduced by single precision floating points; we exploit a compressed out of core representation and speculative prefetching for hiding disk latency during rendering of out-of-core data; we efficiently construct high quality simplified representations with a novel distributed out of core simplification algorithm working on a standard PC network.
Producing high-quality visualizations of large-scale simulation
Authors: Voicu Popescu, Christoph M. Hoffmann, Sami Kilic, Mete Sozen, Scott Meador
Published at Vis, 2003

This paper describes the work of a team of researchers in computer graphics, geometric computing, and civil engineering to produce a visualization of the September 2001 attack on the Pentagon. The immediate motivation for the project was to understand the behavior of the building under the impact. The longer term motivation was to establish a path for producing high-quality visualizations of large scale simulations. The first challenge was managing the enormous complexity of the scene to fit within the limits of state-of-the art simulation software systems and supercomputing resources. The second challenge was to integrate the simulation results into a high-quality visualization. To meet this challenge, we implemented a custom importer that simplifies and loads the massive simulation data in a commercial animation system. The surrounding scene is modeled using image-based techniques and is also imported in the animation system where the visualization is produced. A specific issue for us was to federate the simulation and the animation systems, both commercial systems not under our control and following internally different conceptualizations of geometry and animation. This had to be done such that scalability was achieved. The reusable link created between the two systems allows communicating the results to non-specialists and the public at large, as well as facilitating communication in teams with members having diverse technical backgrounds.
Psychophysical scaling of a cardiovascular information display
Authors: Robert Albert, Noah Syroid, Yinqi Zhang, James Agutter, Frank Drews, David L. Strayer, George Hutchinson, Dwayne R. Westenskow
Published at Vis, 2003

A new method was developed to increase the saliency of changing variables in a cardiovascular visualization for use by anesthesiologists in the operating room (OR). Clinically meaningful changes in patient physiology were identified and then mapped to the inherent psychophysical properties of the visualization. A long history of psychophysical research has provided an understanding of the parameters within which the human information processing system is able to detect changes in the size, shape and color of visual objects (Gescheider, 1976, Spence, 1990, and Baird, 1970). These detection thresholds are known as just noticeable differences (JNDs) which characterize the amount of change in an object's attribute that is recognizable 50% of the time. A prototype version of the display has been demonstrated to facilitate anesthesiologist's performance while reducing cognitive workload during simulated cardiac events (Agutter et al., 2002). In order to further improve the utility of the new cardiovascular visualization, the clinically relevant changes in cardiovascular variables are mapped to noticeable perceptual changes in the representational elements of the display. The results of the method described in this paper are used to merge information from the psychophysical properties of the cardiovascular visualization, with clinically relevant changes in the patient's cardiovascular physiology as measured by the clinical meaningfulness questionnaire. The result of this combination will create a visualization that is sensitive to changes in the cardiovascular health of the patient and communicates this information to the user in a meaningful, salient and intuitive manner.
Quasi-static approach approximation for 6 degrees-of-freedom haptic rendering
Authors: Ming Wan, William A. McNeely
Published at Vis, 2003

In this paper, we propose a quasi-static approximation (QSA) approach to simulate the movement of the movable object in 6-degrees-of-freedom (DOF) haptic rendering. In our QSA approach, we solve for static equilibrium during each haptic time step, ignoring any dynamical properties such as inertia. The major contribution of this approach is to overcome the computational instability problem in overly stiff systems arising from numerical integration of second-order differential equations in previous dynamic models. Our primary experimental results on both simulated aircraft geometry and a large-scale real-world aircraft engine showed that our QSA approach was capable of maintaining the 1000Hz haptic refresh rate with more robust collision avoidance and more reliable force and torque feedback.
Real-time refinement and simplification of adaptive triangular meshes
Authors: Vasily Volkov, Ling Li 0006
Published at Vis, 2003

In this paper we present a generic method for incremental mesh adaptation based on hierarchy of semi-regular meshes. Our method supports any refinement rule mapping vertices onto vertices such as 1-to-4 split or /spl radic/3-subdivision. Resulting adaptive mesh has subdivision connectivity and hence good aspect ratio of triangles. Hierarchic representation of the mesh allows incremental local refinement and simplification operations exploiting frame-to-frame coherence. We also present an out-of-core storage layout scheme designed for semi-regular meshes of arbitrary subdivision connectivity. It provides high cache coherency in the data retrieval and relies on the interleaved storage of resolution levels and maintaining good geometrical proximity within each level. The efficiency of the proposed method is demonstrated with applications in physically-based cloth simulation, real-time terrain visualization and procedural modeling.
Saddle connectors - an approach to visualizing the topological skeleton of complex 3D vector fields
Authors: Holger Theisel, Tino Weinkauf, Hans-Christian Hege, Hans-Peter Seidel
Published at Vis, 2003

One of the reasons that topological methods have a limited popularity for the visualization of complex 3D flow fields is the fact that such topological structures contain a number of separating stream surfaces. Since these stream surfaces tend to hide each other as well as other topological features, for complex 3D topologies the visualizations become cluttered and hardly interpretable. This paper proposes to use particular stream lines called saddle connectors instead of separating stream surfaces and to depict single surfaces only on user demand. We discuss properties and computational issues of saddle connectors and apply these methods to complex flow data. We show that the use of saddle connectors makes topological skeletons available as a valuable visualization tool even for topologically complex 3D flow data.
Shape simplification based on the medial axis transform
Authors: Roger C. Tam, Wolfgang Heidrich
Published at Vis, 2003

We present a new algorithm for simplifying the shape of 3D objects by manipulating their medial axis transform (MAT). From an unorganized set of boundary points, our algorithm computes the MAT, decomposes the axis into parts, then selectively removes a subset of these parts in order to reduce the complexity of the overall shape. The result is simplified MAT that can be used for a variety of shape operations. In addition, a polygonal surface of the resulting shape can be directly generated from the filtered MAT using a robust surface reconstruction method. The algorithm presented is shown to have a number of advantages over other existing approaches.
Signed distance transform using graphics hardware
Authors: Christian Sigg, Ronald Peikert, Markus H. Gross
Published at Vis, 2003

This paper presents a signed distance transform algorithm using graphics hardware, which computes the scalar valued function of the Euclidean distance to a given manifold of co-dimension one. If the manifold is closed and orientable, the distance has a negative sign on one side of the manifold and a positive sign on the other. Triangle meshes are considered for the representation of a two-dimensional manifold and the distance function is sampled on a regular Cartesian grid. In order to achieve linear complexity in the number of grid points, to each primitive we assign a simple polyhedron enclosing its Voronoi cell. Voronoi cells are known to contain exactly all points that lay closest to its corresponding primitive. Thus, the distance to the primitive only has to be computed for grid points inside its polyhedron. Although Voronoi cells partition space, the polyhedrons enclosing these cells do overlap. In regions where these overlaps occur, the minimum of all computed distances is assigned to a grid point. In order to speed up computations, points inside each polyhedron are determined by scan conversion of grid slices using graphics hardware. For this task, a fragment program is used to perform the nonlinear interpolation and minimization of distance values.
Space efficient fast isosurface extraction for large datasets
Authors: Udeepta Bordoloi, Han-Wei Shen
Published at Vis, 2003

In this paper, we present a space efficient algorithm for speeding up isosurface extraction. Even though there exist algorithms that can achieve optimal search performance to identify isosurface cells, they prove impractical for large datasets due to a high storage overhead. With the dual goals of achieving fast isosurface extraction and simultaneously reducing the space requirement, we introduce an algorithm based on transform coding to compress the interval information of the cells in a dataset. Compression is achieved by first transforming the cell intervals (minima, maxima) into a form which allows more efficient compaction. It is followed by a dataset optimized non-uniform quantization stage. The compressed data is stored in a data structure that allows fast searches in the compression domain, thus eliminating the need to retrieve the original representation of the intervals at run-time. The space requirement of our search data structure is the mandatory cost of storing every cell ID once, plus an overhead for quantization information. The overhead is typically in the order of a few hundredths of the dataset size.
The visualization market: open source vs. commercial approaches
Authors: Jeremy Jaech, Stephen C. North, Mike Peery, Will Schroeder, James J. Thomas
Published at Vis, 2003

This forum examines the question of when commercial software makes sense and when open-source software is more appropriate. Visualization software runs the gamut from very general-purpose applications intended for the graphically challenged to highly specific software libraries intended for the sophisticated visualization expert. Where along that spectrum is the realm of commercial software, and where does open-source software make sense? Should all visualization software be open source? Why might end users choose to purchase visualization tools instead of using opensource tools?
Using deformations for browsing volumetric data
Authors: Michael J. McGuffin, Liviu Tancau, Ravin Balakrishnan
Published at Vis, 2003

Many traditional techniques for "looking inside" volumetric data involve removing portions of the data, for example using various cutting tools, to reveal the interior. This allows the user to see hidden parts of the data, but has the disadvantage of removing potentially important surrounding contextual information. We explore an alternate strategy for browsing that uses deformations, where the user can cut into and open up, spread apart, or peel away parts of the volume in real time, making the interior visible while still retaining surrounding context. We consider various deformation strategies and present a number of interaction techniques based on different metaphors. Our designs pay special attention to the semantic layers that might compose a volume (e.g. the skin, muscle, bone in a scan of a human). Users can apply deformations to only selected layers, or apply a given deformation to a different degree to each layer, making browsing more flexible and facilitating the visualization of relationships between layers. Our interaction techniques are controlled with direct, "in place" manipulation, using pop-up menus and 3D widgets, to avoid the divided attention and awkwardness that would come with panels of traditional widgets. Initial user feedback indicates that our techniques are valuable, especially for showing portions of the data spatially situated in context with surrounding data.
Vicinity shading for enhanced perception of volumetric data
Authors: A. James Stewart
Published at Vis, 2003

This paper presents a shading model for volumetric data which enhances the perception of surfaces within the volume. The model incorporates uniform diffuse illumination, which arrives equally from all directions at each surface point in the volume. This illumination is attenuated by occlusions in the local vicinity of the surface point, resulting in shadows in depressions and crevices. Experiments by other authors have shown that perception of a surface is superior under uniform diffuse lighting, compared to illumination from point source lighting.
Video visualization
Authors: Gareth Daniel, Min Chen 0001
Published at Vis, 2003

Video data, generated by the entertainment industry, security and traffic cameras, video conferencing systems, video emails, and so on, is perhaps most time-consuming to process by human beings. In this paper, we present a novel methodology for "summarizing" video sequences using volume visualization techniques. We outline a system pipeline for capturing videos, extracting features, volume rendering video and feature data, and creating video visualization. We discuss a collection of image comparison metrics, including the linear dependence detector, for constructing "relative" and "absolute" difference volumes that represent the magnitude of variation between video frames. We describe the use of a few volume visualization techniques, including volume scene graphs and spatial transfer functions, for creating video visualization. In particular, we present a stream-based technique for processing and directly rendering video data in real time. With the aid of several examples, we demonstrate the effectiveness of using video visualization to convey meaningful information contained in video sequences.
Visibility based methods and assessment for detail-recovery
Authors: Marco Tarini, Paolo Cignoni, Roberto Scopigno
Published at Vis, 2003

In this paper we propose a new method for the creation of normal maps for recovering the detail on simplified meshes and a set of objective techniques to metrically evaluate the quality of different recovering techniques. The proposed techniques, that automatically produces a normal-map texture for a simple 3D model that "imitates" the high frequency detail originally present in a second, much higher resolution one, is based on the computation of per-texel visibility and self-occlusion information. This information is used to define a point-to-point correspondence between simplified and hires meshes. Moreover, we introduce a number of criteria for measuring the quality (visual or otherwise) of a given mapping method, and provide efficient algorithms to implement them. Lastly, we apply them to rate different mapping methods, including the widely used ones and the new one proposed here.