IEEE VIS Publication Dataset

Modular visualization environments (MVEs) have recently been regarded as the de facto standard for scientific data visualization, mainly due to adoption of the visual programming style, reusability, and extendability. However, since scientists and engineers as the MVE principal user are not always familiar with how to map numerical data to proper graphical primitives, the set of built-in modules is not fully used to construct necessary application networks. Therefore, a certain mechanism needs to be incorporated into MVEs, which makes use of heuristics and expertise of visualization specialists (visineers), and which supports the user in designing his/her applications with MVEs. The Wehrend's goal-oriented taxonomy of visualization techniques is adopted as the basic philosophy to develop a system, called GADGET, for application design guidance for MVEs. The GADGET system interactively helps the user design appropriate applications according to the specific visualization goals, temporal efficiency versus accuracy requirements, and such properties as dimension and mesh type of a given target dataset. Also the GADGET system is capable of assisting the user in customizing a prototype modular network for his/her desired applications by showing execution examples involving datasets of the same type. The paper provides an overview of the GADGET guidance mechanism and system architecture, with an emphasis on its knowledge base design. Sample data visualization problems are used to demonstrate the usefulness of the GADGET system.

Some new piecewise constant wavelets defined over nested triangulated domains are presented and applied to the problem of multiresolution analysis of flow over a spherical domain. These new, nearly orthogonal wavelets have advantages over the existing weaker biorthogonal wavelets. In the planar case of uniform areas, the wavelets converge to one of two fully orthogonal Haar wavelets. These new, fully orthogonal wavelets are proven to be the only possible wavelets of this type.

The authors give I/O-optimal techniques for the extraction of isosurfaces from volumetric data, by a novel application of the I/O-optimal interval tree of Arge and Vitter (1996). The main idea is to preprocess the data set once and for all to build an efficient search structure in disk, and then each time one wants to extract an isosurface, they perform an output-sensitive query on the search structure to retrieve only those active cells that are intersected by the isosurface. During the query operation, only two blocks of main memory space are needed, and only those active cells are brought into the main memory, plus some negligible overhead of disk accesses. This implies that one can efficiently visualize very large data sets on workstations with just enough main memory to hold the isosurfaces themselves. The implementation is delicate but not complicated. They give the first implementation of the I/O-optimal interval tree, and also implement their methods as an I/O filter for Vtk's isosurface extraction for the case of unstructured grids. They show that, in practice, the algorithms improve the performance of isosurface extraction by speeding up the active-cell searching process so that it is no longer a bottleneck. Moreover, this search time is independent of the main memory available. The practical efficiency of the techniques reflects their theoretical optimality.

The authors present an image synthesis methodology and a system built around it. Given a sparse set of photographs taken from unknown viewpoints, the system generates images from new, different viewpoints with correct perspective, and handles occlusion. It achieves this without requiring any knowledge about the 3D structure of the scene nor the intrinsic camera parameters. The photo-realistic rendering process is polygon based and can be potentially implemented as real time texture mapping. The system is robust to noise by taking advantage of duplicate information from multiple views. They present results on several example scenes.

We describe a multidisciplinary effort for creating interactive 3D graphical modules for visualizing optical phenomena. These modules are designed for use in an upper-level undergraduate course. The modules are developed in Open Inventor, which allows them to run under both Unix and Windows. The work is significant in that it applies contemporary interactive 3D visualization techniques to instructional courseware, which represents a considerable advance compared to the current state of the practice.

Volumetric data sets require enormous storage capacity even at moderate resolution levels. The excessive storage demands not only stress the capacity of the underlying storage and communications systems, but also seriously limit the speed of volume rendering due to data movement and manipulation. A novel volumetric data visualization scheme is proposed and implemented in this work that renders 2D images directly from compressed 3D data sets. The novelty of this algorithm is that rendering is performed on the compressed representation of the volumetric data without pre-decompression. As a result, the overheads associated with both data movement and rendering processing are significantly reduced. The proposed algorithm generalizes previously proposed whole-volume frequency-domain rendering schemes by first dividing the 3D data set into subcubes, transforming each subcube to a frequency-domain representation, and applying the Fourier projection theorem to produce the projected 2D images according to given viewing angles. Compared to the whole-volume approach, the subcube-based scheme not only achieves higher compression efficiency by exploiting local coherency, but also improves the quality of resultant rendering images because it approximates the occlusion effect on a subcube by subcube basis.

Presents a system for interactively visualizing large polygonal environments such as those produced by CAD systems during the design of aircraft and power generation engines. Our method combines view frustum culling with level-of-detail modeling to create a visualization system that supports part motion and has the ability to view arbitrary sets of data. To avoid long system start-up delays due to data loading, we have implemented our system using a dynamic loading strategy. This also allows us to interactively visualize more data than could fit in memory at one time.

3D virtual colonoscopy has recently been proposed as a non-invasive alternative procedure for the visualization of the human colon. Surface rendering is sufficient for implementing such a procedure to obtain an overview of the interior surface of the colon at interactive rendering speeds. Unfortunately, physicians can not use it to explore tissues beneath the surface to differentiate between benign and malignant structures. In this paper, we present a direct volume rendering approach based on perspective ray casting, as a supplement to the surface navigation. To accelerate the rendering speed, surface-assistant techniques are used to adapt the resampling rates by skipping the empty space inside the colon. In addition, a parallel version of the algorithm has been implemented on a shared-memory multiprocessing architecture. Experiments have been conducted on both simulation and patient data sets.

The interval volume is a generalization of the isosurface commonly associated with the marching cubes algorithm. Based upon samples at the locations of a 3D rectilinear grid, the algorithm produces a triangular approximation to the surface defined by F(x,y,z)=c. The interval volume is defined by ╬▒ÔëñF(x,y,z)Ôëñ╬▓. The authors describe an algorithm for computing a tetrahedrization of a polyhedral approximation to the interval volume.

Presents a new approach to isosurface extraction from volume data using particle systems. Particle behavior is dynamic and can be based on laws of physics or artificial rules. For isosurface extraction, we program particles to be attracted towards a specific surface value while simultaneously repelling adjacent particles. The repulsive forces are based on the curvature of the surface at that location. A birth-death process results in a denser concentration of particles in areas of high curvature and sparser populations in areas of lower curvature. The overall level of detail is controlled through a scaling factor that increases or decreases the repulsive forces of the particles. Once particles reach equilibrium, their locations are used as vertices in generating a triangular mesh of the surface. The advantages of our approach include: vertex densities are based on surface features rather than on the sampling rate of the volume; a single scaling factor simplifies level-of-detail control; and meshing is efficient because it uses neighbor information that has already been generated during the force calculations.

The paper presents a framework for multiresolution compression and geometric reconstruction of arbitrarily dimensioned data designed for distributed applications. Although being restricted to uniform sampled data, the versatile approach enables the handling of a large variety of real world elements. Examples include nonparametric, parametric and implicit lines, surfaces or volumes, all of which are common to large scale data sets. The framework is based on two fundamental steps: compression is carried out by a remote server and generates a bit-stream transmitted over the underlying network. Geometric reconstruction is performed by the local client and renders a piecewise linear approximation of the data. More precisely, the compression scheme consists of a newly developed pipeline starting from an initial B-spline wavelet precoding. The fundamental properties of wavelets allow progressive transmission and interactive control of the compression gain by means of global and local oracles. In particular the authors discuss the problem of oracles in semiorthogonal settings and propose sophisticated oracles to remove unimportant coefficients. In addition, geometric constraints such as boundary lines can be compressed in a lossless manner and are incorporated into the resulting bit-stream. The reconstruction pipeline performs a piecewise adaptive linear approximation of data using a fast and easy to use point removal strategy which works with any subsequent triangulation technique.

The authors present a multiresolution framework, called Multi-Tetra framework, that approximates volume data with different levels-of-detail tetrahedra. The framework is generated through a recursive subdivision of the volume data and is represented by binary trees. Instead of using a certain level of the Multi-Tetra framework for approximation, an error-based model (EBM) is generated by recursively fusing a sequence of tetrahedra from different levels of the Multi-Tetra framework. The EBM significantly reduces the number of voxels required to model an object, while preserving the original topology. The approach provides continuous distribution of rendered intensity or generated isosurfaces along boundaries of different levels-of-detail thus solving the crack problem. The model supports typical rendering approaches, such as marching cubes, direct volume projection, and splatting. Experimental results demonstrate the strengths of the approach.

The authors present an efficient visualization approach to support multivariate data exploration through a simple but effective low dimensional data overview based on metric scaling. A multivariate dataset is first transformed into a set of dissimilarities between all pairs of data records. A graph configuration algorithm based on principal components is then wed to determine the display coordinates of the data records in the low dimensional data overview. This overview provides a graphical summary of the multivariate data with reduced data dimensions, reduced data size, and additional data semantics. It can be used to enhance multidimensional data brushing, or to arrange the layout of other conventional multivariate visualization techniques. Real life data is used to demonstrate the approach.

Most existing visualization applications use 3D geometry as their basic rendering primitive. As users demand more complex data sets, the memory requirements for retrieving and storing large 3D models are becoming excessive. In addition, the current 3D rendering hardware is facing a large memory bus bandwidth bottleneck at the processor to graphics pipeline interface. Rendering 1 million triangles with 24 bytes per triangle at 30 Hz requires as much as 720 MB/sec memory bus bandwidth. This transfer rate is well beyond the current low-cost graphics systems. A solution is to compress the static 3D geometry as an off-line pre-process. Then, only the compressed geometry needs to be stored in main memory and sent down to the graphics pipeline for real-time decompression and rendering. The author presents several new techniques for compression of 3D geometry that produce 2 to 3 times better compression ratios than existing methods. They first introduce several algorithms for the efficient encoding of the original geometry as generalized triangle meshes. This encoding allows most of the mesh vertices to be reused when forming new triangles. Their second contribution allows various parts of a geometric model to be compressed with different precision depending on the level of details present. Together, the meshifying algorithms and the variable compression method achieve compression ratios of 30 and 37 to one over ASCII encoded formats and 10 and 15 to one over binary encoded triangle strips. The experimental results show a dramatically lowered memory bandwidth required for real-time visualization of complex data sets.

Since 1991, our team of computer scientists, chemists and physicists have worked together to develop an advanced, virtual-environment interface to scanned-probe microscopes. The interface has provided insights and useful capabilities well beyond those of the traditional interface. This paper lists the particular visualization and control techniques that have enabled actual scientific discovery, including specific examples of insight gained using each technique. This information can help scientists determine which features are likely to be useful in their particular application, and which would be just sugar coating. It can also guide computer scientists to suggest the appropriate type of interface to help solve a particular problem. We have found benefit in advanced rendering with natural viewpoint control (but not always), from semi-automatic control techniques, from force feedback during manipulation, and from storing/replaying data for an entire experiment. These benefits come when the system is well-integrated into the existing tool and allows export of the data to standard visualization packages.

The use of stream surfaces and streamlines is well established in vector visualization. However, the proper placement of starting points is critical for these constructs to clearly illustrate the flow topology. In this paper, we present the principal stream surface algorithm, which automatically generates stream surfaces that properly depict the topology of an irrotational flow. For each velocity point in the fluid field, we construct the normal to the principal stream surface through the point. The set of all such normal vectors is used to construct the principal stream function, which is a scalar field describing the direction of velocity in the fluid field. Volume rendering can then be used to visualize the principal stream function, which is directly related to the flow topology. Thus, topology in a fluid field can be easily modeled and rendered.

We describe an algorithm for repairing polyhedral CAD models that have errors in their B-REP. Errors like cracks, degeneracies, duplication, holes and overlaps are usually introduced in solid models due to imprecise arithmetic, model transformations, designer errors, programming bugs, etc. Such errors often hamper further processing such as finite element analysis, radiosity computation and rapid prototyping. Our fault-repair algorithm converts an unordered collection of polygons to a shared-vertex representation to help eliminate errors. This is done by choosing, for each polygon edge, the most appropriate edge to unify it with. The two edges are then geometrically merged into one, by moving vertices. At the end of this process, each polygon edge is either coincident with another or is a boundary edge for a polygonal hole or a dangling wall and may be appropriately repaired. Finally, in order to allow user-inspection of the automatic corrections, we produce a visualization of the repair and let the user mark the corrections that conflict with the original design intent. A second iteration of the correction algorithm then produces a repair that is commensurate with the intent. This, by involving the users in a feedback loop, we are able to refine the correction to their satisfaction.

Terrain visualization is a difficult problem for applications requiring accurate images of large datasets at high frame rates, such as flight simulation and ground-based aircraft testing using synthetic sensor simulation. On current graphics hardware, the problem is to maintain dynamic, view-dependent triangle meshes and texture maps that produce good images at the required frame rate. We present an algorithm for constructing triangle meshes that optimizes flexible view-dependent error metrics, produces guaranteed error bounds, achieves specified triangle counts directly and uses frame-to-frame coherence to operate at high frame rates for thousands of triangles per frame. Our method, dubbed Real-time Optimally Adapting Meshes (ROAM), uses two priority queues to drive split and merge operations that maintain continuous triangulations built from pre-processed bintree triangles. We introduce two additional performance optimizations: incremental triangle stripping and priority-computation deferral lists. ROAM's execution time is proportional to the number of triangle changes per frame, which is typically a few percent of the output mesh size; hence ROAM's performance is insensitive to the resolution and extent of the input terrain. Dynamic terrain and simple vertex morphing are supported.