DevLan/vispubs huggingface dataset:
Importance-driven volume rendering
Authors: Ivan Viola, Armin Kanitsar, M. Eduard Gröller
Published at Vis, 2004

This work introduces importance-driven volume rendering as a novel technique for automatic focus and context display of volumetric data. Our technique is a generalization of cut-away views, which - depending on the viewpoint - remove or suppress less important parts of a scene to reveal more important underlying information. We automatize and apply this idea to volumetric data. Each part of the volumetric data is assigned an object importance, which encodes visibility priority. This property determines which structures should be readily discernible and which structures are less important. In those image regions, where an object occludes more important structures it is displayed more sparsely than in those areas where no occlusion occurs. Thus the objects of interest are clearly visible. For each object several representations, i.e., levels of sparseness, are specified. The display of an individual object may incorporate different levels of sparseness. The goal is to emphasize important structures and to maximize the information content in the final image. This work also discusses several possible schemes for level of sparseness specification and different ways how object importance can be composited to determine the final appearance of a particular object.
Interactive design of multi-perspective images for visualizing urban landscapes
Authors: Augusto Román, Gaurav Garg, Marc Levoy
Published at Vis, 2004

Multiperspective images are a useful way to visualize extended, roughly planar scenes such as landscapes or city blocks. However, constructing effective multiperspective images is something of an art. We describe an interactive system for creating multiperspective images composed of serially blended cross-slits images. Beginning with a sideways-looking video of the scene as might be captured from a moving vehicle, we allow the user to interactively specify a set of cross-slits cameras, possibly with gaps between them. In each camera, one of the slits is defined to be the camera path, which is typically horizontal, and the user is left to choose the second slit, which is typically vertical. The system then generates intermediate views between these cameras using a novel interpolation scheme, thereby producing a multiperspective image with no seams. The user can also choose the picture surface in space onto which viewing rays are projected, thereby establishing a parameterization for the image. We show how the choice of this surface can be used to create interesting visual effects. We demonstrate our system by constructing multiperspective images that summarize city blocks, including corners, blocks with deep plazas and other challenging urban situations.
Interactive exploration of large remote micro-CT scans
Authors: Steffen Prohaska, Andrei Hutanu, Ralf Kähler, Hans-Christian Hege
Published at Vis, 2004

Datasets of tens of gigabytes are becoming common in computational and experimental science. This development is driven by advances in imaging technology, producing detectors with growing resolutions, as well as availability of cheap processing power and memory capacity in commodity-based computing clusters. We describe the design of a visualization system that allows scientists to interactively explore large remote data sets in an efficient and flexible way. The system is broadly applicable and currently used by medical scientists conducting an osteoporosis research project. Human vertebral bodies are scanned using a high resolution microCT scanner producing scans of roughly 8 GB size each. All participating research groups require access to the centrally stored data. Due to the rich internal bone structure, scientists need to interactively explore the full dataset at coarse levels, as well as visualize subvolumes of interest at the highest resolution. Our solution is based on HDF5 and GridFTP. When accessing data remotely, the HDF5 data processing pipeline is modified to support efficient retrieval of subvolumes. We reduce the overall latency and optimize throughput by executing high-level operations on the remote side. The GridFTP protocol is used to pass the HDF5 requests to a customized server. The approach takes full advantage of local graphics hardware for rendering. Interactive visualization is accomplished using a background thread to access the datasets stored in a multiresolution format. A hierarchical volume tenderer provides seamless integration of high resolution details with low resolution overviews.
Interactive point-based isosurface extraction
Authors: Yarden Livnat, Xavier Tricoche
Published at Vis, 2004

We propose a novel point-based approach to view dependent isosurface extraction. We introduce a fast visibility query system for the view dependent traversal, which exhibits moderate memory requirements. This technique allows for an interactive interrogation of the full visible woman dataset (1GB) at four to fifteen frames per second on a desktop computer. The point-based approach is built on an extraction scheme that classifies different sections of the isosurface into four categories, depending on the size of the geometry when projected onto the screen. In particular, we use points to represent small and subpixel triangles, as well as larger sections of the isosurface whose projection has subpixel size. To assign consistent and robust normals to individual points representing such regions, we propose to compute them during post processing of the extracted isosurface and provide the corresponding hardware implementation.
Interactive Poster: Grid-Enabled Collaborative Scientific Visualization Environment
Authors: Eric Christopher Wyatt, Patrick O'Leary
Published at Vis, 2004

At its core, the grid is concerned with distributed computing and resource management. In essence, the grid is the federation and virtualization of computing resources to accelerate application processing [Unger-Haynos]. As described by Foster et al, grid computing focuses on large-scale resource sharing between dynamic collections of individuals, institutions, and resources via flexible, secure, and coordinated mechanisms.
Interactive Poster: Illustrating Different Convection Velocities of Turbulent Flow
Authors: Timothy Urness, Victoria Interrante, Ellen Longmire, Ivan Marusic, Bharathram Ganapathisubramani
Published at Vis, 2004

The visualization of any vector field is dependent on the relative velocity of the observer. In experimentally generated vector fields, the average value of the streamwise component of the global vector field is typically calculated and subtracted from each vector. We demonstrate that the resulting image, critical points, and vector field features are greatly influenced by the magnitude of the value subtracted from the streamwise velocity.
Interactive terascale particle visualization
Authors: David Ellsworth, Bryan Green, Patrick J. Moran
Published at Vis, 2004

This work describes the methods used to produce an interactive visualization of a 2 TB computational fluid dynamics (CFD) data set using particle tracing (streaklines). We use the method introduced by Bruckschen el al. (2001) that precomputes a large number of particles, stores them on disk using a space-filling curve ordering that minimizes seeks, then retrieves and displays the particles according to the user's command. We describe how the particle computation can be performed using a PC cluster, how the algorithm can be adapted to work with a multiblock curvilinear mesh, how scalars can be extracted and used to color the particles, and how the out-of-core visualization can be scaled to 293 billion particles while still achieving interactive performance on PC hardware. Compared to the earlier work, our data set size and total number of particles are an order of magnitude larger. We also describe a new compression technique that losslessly reduces the amount of particle storage by 41% and speeds the particle retrieval by about 20%.
Interactive thickness visualization of articular cartilage
Authors: Matej Mlejnek, Anna Vilanova, M. Eduard Gröller
Published at Vis, 2004

This work describes a method to visualize the thickness of curved thin objects. Given the MRI volume data of articular cartilage, medical doctors investigate pathological changes of the thickness. Since the tissue is very thin, it is impossible to reliably map the thickness information by direct volume rendering. Our idea is based on unfolding of such structures preserving their thickness. This allows to perform anisotropic geometrical operations (e.g., scaling the thickness). However, flattening of a curved structure implies a distortion of its surface. The distortion problem is alleviated through a focus-and-context minimization approach. Distortion is smallest close to a focal point which can be interactively selected by the user.
Introducing Topological Attributes for Objective-Based Visualization
Authors: Yuriko Takeshima, Shigeo Takahashi, Issei Fujishiro, Gregory M. Nielson
Published at Vis, 2004

Direct volume rendering is a standard technique for projecting all the optically-encoded samples onto the screen at once to allow us to peer into the inner structures involved in a volume data. Datacentric approaches to the design of transfer functions (TFs) have recently been well-established, which perform mathematical analysis of the data prior to pertinent rendering. The advent of multidimensional TFs is one of the latest major achievements in the volume visualization research. As opposed to the traditional onedimensional TFs that only consider a voxel’s scalar field value, the multi-dimensional TFs assign auxiliary attributes to the voxels to construct their sophisticated parametric domains. For example, when visualizing volumes obtained by scientific simulations, the observers can utilize their own knowledge about the simulation settings to extract the global characteristics of the volumes and to locate regions of particular interest. If they are allowed to design multi-dimensional TFs using staff attributes so as to encapsulate such advance knowledge, they can readily yield visualization results to fulfill their purposes. Nevertheless, nearly all attributes for the conventional multi-dimensional TFs are based on local features, such as differentials and curvatures, and are difficult to capture the global structure of the volume contrary to the observer’s purposes. This paper therefore introduces a new set of topological attributes to establish a new framework that is intended to realize objective-based assistance. Topological attributes proposed herein are derived from the level-set graph, which delineates the topological evolution of an isosurface with respect to the scalar field.
Intuitive and interactive modification of large finite element models
Authors: Dirc Rose, Katrin Bidmon, Thomas Ertl
Published at Vis, 2004

Virtual prototyping is increasingly replacing real mock-ups and experiments in industrial product development. Part of this process is the simulation of structural and functional properties, which is in many cases based on finite element analysis (FEA). One prominent example from the automotive industry is the safety improvement resulting from crash worthiness simulations. A simulation model for this purpose usually consists of up to one million finite elements and is assembled from many parts, which are individually meshed out of their CAD representation. In order to accelerate the development cycle, simulation engineers want to be able to modify their FE models without going back to the CAD department. Furthermore, valid CAD models might even not be available in preliminary design stages. However, in contrast to CAD, there is a lack of tools that offer the possibility of modification and processing of finite element components while maintaining the properties relevant to the simulation. In this application paper we present interactive algorithms for intuitive and fast editing of FE models and appropriate visualization techniques to support engineers in understating these models. This includes new kinds of manipulators, feedback mechanisms and facilities for virtual reality and immersion at the workplace, e.g. autostereoscopic displays and haptic devices.
Investigating swirl and tumble flow with a comparison of visualization techniques
Authors: Robert S. Laramee, Daniel Weiskopf, Jürgen Schneider, Helwig Hauser
Published at Vis, 2004

We investigate two important, common fluid flow patterns from computational fluid dynamics (CFD) simulations, namely, swirl and tumble motion typical of automotive engines. We study and visualize swirl and tumble flow using three different flow visualization techniques: direct, geometric, and texture-based. When illustrating these methods side-by-side, we describe the relative strengths and weaknesses of each approach within a specific spatial dimension and across multiple spatial dimensions typical of an engineer's analysis. Our study is focused on steady-state flow. Based on this investigation we offer perspectives on where and when these techniques are best applied in order to visualize the behavior of swirl and tumble motion.
JointViewer - An Interactive System for Exploring Orthopedic Data
Authors: G. Elisabeta Marai, Çagatay Demiralp, Stuart Andrews, David H. Laidlaw
Published at Vis, 2004

We present JointViewer, a software tool to aid orthopedics researchers in exploring complex, in-vivo joint kinematics. Given bone-geometry data and bone-motion information, JointViewer models and visualizes bone inter-spacing in the joint. Next, it proposes and displays plausible ligament paths which connect bones together. Both types of models are constructed through a distancefield approach. Users can maneuver the bones in a joint for better viewing, see motion relative to a specific bone, or remove bones from a joint. We demonstrate JointViewer’s effectiveness in three applications: examining normal human wrist kinematics, capturing the effect of injury on forearm kinematics, and exploring the kinematic constraints imposed by ligaments in a pigeon shoulder. In all applications, the system effectively highlights subtle yet important relationships among bones and soft-tissue that in previous standard joint visualizations had gone unnoticed.
Light Collages: lighting design for effective visualization
Authors: Chang Ha Lee, Xuejun Hao, Amitabh Varshney
Published at Vis, 2004

We introduce Light Collages - a lighting design system for effective visualization based on principles of human perception. Artists and illustrators enhance perception of features with lighting that is locally consistent and globally inconsistent. Inspired by these techniques, we design the placement of light sources to convey a greater sense of realism and better perception of shape with globally inconsistent lighting. Our algorithm segments the objects into local surface patches and uses a number of perceptual heuristics, such as highlights, shadows, and silhouettes, to enhance the perception of shape. We show our results on scientific and sculptured datasets.
Light weight space leaping using ray coherence
Authors: Sarang Lakare, Arie E. Kaufman
Published at Vis, 2004

We present a space leaping technique for accelerating volume rendering with very low space and run-time complexity. Our technique exploits the ray coherence during ray casting by using the distance a ray traverses in empty space to leap its neighboring rays. Our technique works with parallel as well as perspective volume rendering, does not require any preprocessing or 3D data structures, and is independent of the transfer function. Being an image-space technique, it is independent of the complexity of the data being rendered. It can be used to accelerate both time-coherent and noncoherent animation sequences.
Lighting transfer functions using gradient aligned sampling
Authors: Eric B. Lum, Kwan-Liu Ma
Published at Vis, 2004

An important task in volume rendering is the visualization of boundaries between materials. This is typically accomplished using transfer functions that increase opacity based on a voxel's value and gradient. Lighting also plays a crucial role in illustrating surfaces. In this paper we present a multi-dimensional transfer function method for enhancing surfaces, not through the variation of opacity, but through the modification of surface shading. The technique uses a lighting transfer function that takes into account the distribution of values along a material boundary and features a novel interface for visualizing and specifying these transfer functions. With our method, the user is given a means of visualizing boundaries without modifying opacity, allowing opacity to be used for illustrating the thickness of homogeneous materials through the absorption of light.
Linear and cubic box splines for the body centered cubic lattice
Authors: Alireza Entezari, Ramsay Dyer, Torsten Möller
Published at Vis, 2004

We derive piecewise linear and piecewise cubic box spline reconstruction filters for data sampled on the body centered cubic (BCC) lattice. We analytically derive a time domain representation of these reconstruction filters and using the Fourier slice-projection theorem we derive their frequency responses. The quality of these filters, when used in reconstructing BCC sampled volumetric data, is discussed and is demonstrated with a raycaster. Moreover, to demonstrate the superiority of the BCC sampling, the resulting reconstructions are compared with those produced from similar filters applied to data sampled on the Cartesian lattice.
Linking Representation with Meaning
Authors: David J. Duke
Published at Vis, 2004

The purpose of visualization is not just to depict data, but to gain or present insight into the domain represented in data. However in visualization systems, this link between features in the data and the meaning of those features is often missing or implicit. It is assumed that the user, through looking at the output, will close the loop between representation and insight. An alternative is to view visualization tools as interfaces between data and insight, and to enrich this interface with capabilities linked to users’ conceptual models of the data. Preliminary work has been carried out to develop such an interface as a modular component that can be installed in a pipelined architecture. This poster expands the motivation for this work, and describes the initial implementation carried out within the Visualization Toolkit (VTK).
Live Range Visibility Constraints for Adaptive Terrain Visualization
Authors: Xiaohong Bao, Renato Pajarola, Michael Shafae
Published at Vis, 2004

Although there is a remarkable pace in the advance of computational resources and storage for real-time visualization the immensity of the input data continues to outstrip any advances. The task for interactively visualizing such a massive terrain is to render a triangulated mesh using a view-dependent error tolerance, thus intelligently and perceptually managing the scene’s geometric complexity. At any particular instance in time (i.e. displayed frame), this level-of-detail (LOD) terrain surface consists of a mesh composed of hundreds of thousands of dynamically selected triangles. The triangles are selected using the current time-step’s view parameters and the view-dependent error tolerance. Massive terrain data easily exceeds main memory storage capacity such that out-of-core rendering must be performed. This further complicates the triangle selection and terrain rendering owing to tertiary storage’s relatively poor performance.
Local and global comparison of continuous functions
Authors: Herbert Edelsbrunner, John Harer, Vijay Natarajan, Valerio Pascucci
Published at Vis, 2004

We introduce local and global comparison measures for a collection of k /spl les/ d real-valued smooth functions on a common d-dimensional Riemannian manifold. For k = d = 2 we relate the measures to the set of critical points of one function restricted to the level sets of the other. The definition of the measures extends to piecewise linear functions for which they are easy to compute. The computation of the measures forms the centerpiece of a software tool which we use to study scientific datasets.
LoD volume rendering of FEA data
Authors: Shyh-Kuang Ueng, Yan-Jen Su, Chi-Tang Chang
Published at Vis, 2004

A new multiple resolution volume rendering method for finite element analysis (FEA) data is presented. Our method is composed of three stages: in the first stage, the Gauss points of the FEA cells are calculated. The function values, gradients, diffusions, and influence scopes of the Gauss points are computed. By representing the Gauss points as graph vertices and connecting adjacent Gauss points with edges, an adjacency graph is created. The adjacency graph is used to represent the FEA data in the subsequent computation. In the second stage, a hierarchical structure is established upon the adjacency graph. Any two neighboring vertices with similar function values are merged into a new vertex. The similarity is measured by using a user-defined threshold. Consequently, a new adjacency graph is constructed. Then the threshold is increased, and the graph reduction is triggered again to generate another adjacency graph. By repeating the processing, multiple adjacency graphs are computed, and a level of detail (LoD) representation of the FEA data is established. In the third stage, the LoD structure is rendered by using a splatting method. At first, a level of adjacency graph is selected by users. The graph vertices arc sorted based on their visibility orders and projected onto the image plane in back-to-front order. Billboards are used to render the vertices in the projection. The function values, gradients, and influence scopes of the vertices are utilized to decide the colors, opacities, orientations, and shapes of the billboards. The billboards are then modulated with texture maps to generate the footprints of the vertices. Finally, these footprints are composited to produce the volume rendering image.
Methods for efficient, high quality volume resampling in the frequency domain
Authors: Aili Li, Klaus Mueller 0001, Thomas Ernst 0001
Published at Vis, 2004

Resampling is a frequent task in visualization and medical imaging. It occurs whenever images or volumes are magnified, rotated, translated, or warped. Resampling is also an integral procedure in the registration of multimodal datasets, such as CT, PET, and MRI, in the correction of motion artifacts in MRI, and in the alignment of temporal volume sequences in fMRI. It is well known that the quality of the resampling result depends heavily on the quality of the interpolation filter used. However, high-quality filters are rarely employed in practice due to their large spatial extents. We explore a new resampling technique that operates in the frequency-domain where high-quality filtering is feasible. Further, unlike previous methods of this kind, our technique is not limited to integer-ratio scaling factors, but can resample image and volume datasets at any rate. This would usually require the application of slow discrete Fourier transforms (DFT) to return the data to the spatial domain. We studied two methods that successfully avoid these delays: the chirp-z transform and the FFTW package. We also outline techniques to avoid the ringing artifacts that may occur with frequency-domain filtering. Thus, our method can achieve high-quality interpolation at speeds that are usually associated with spatial filters of far lower quality.
Modeling Decomposing Objects under Combustion
Authors: Zeki Melek, John Keyser
Published at Vis, 2004

We present a simple yet effective method for modeling of object decomposition under combustion. A separate simulation models the flame production and generates heat from a combustion process, which is used to trigger pyrolysis of the solid object. The decomposition is modeled using level set methods, and can handle complex topological changes. Even with a very simple flame model on a coarse grid, we can achieve a plausible decomposition of the burning object.