RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR
VO 16
IS 2
SP 350
TI Errata to “Isosurface Extraction and View-Dependent Filtering from Time-Varying Fields Using Persistent Time-Octree (PTOT)” [Nov-Dec 09 1367-1374]
A1 Cong Wang,
A1 Yi-Jen Chiang,
A1 undefined,
A1 undefined,
A1 undefined,
A1 undefined, K1 Filtering
K1 Visualization
K1 Computer graphics
K1 Computer science
K1 Binary search trees
K1 Computational modeling

AB In the above titled paper (ibid., vol. 15, no. 6, pp. 1367-1374, Nov.-Dec. 09), there were errors contained in Figs. 1, 2, 3, and 4. The correct figures are presented here.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2010.15
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2010.15

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR
VO 16
IS 2
SP 352
TI Corrections to “A Physiologically-Based Model for Simulation of Color Vision Deficiency“ [Nov-Dec 09 1291-1298]K1 Color
K1 Equations
K1 Computational modeling
K1 Visualization
K1 Computer graphics

AB In the above titled paper (ibid., vol. 15, no. 6, pp. 1291-1298, Nov./Dec. 09), there were typos in equations (17) and (18). The correct versions are presented here.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2010.10
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2010.10

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 261
TI Real-Time Ray Tracing of Implicit Surfaces on the GPU
A1 P.J. Narayanan,
A1 Jag Mohan Singh,
K1 Ray tracing
K1 implicit surfaces
K1 GPU rendering.
AB Compact representation of geometry using a suitable procedural or mathematical model and a ray-tracing mode of rendering fit the programmable graphics processor units (GPUs) well. Several such representations including parametric and subdivision surfaces have been explored in recent research. The important and widely applicable category of the general implicit surface has received less attention. In this paper, we present a ray-tracing procedure to render general implicit surfaces efficiently on the GPU. Though only the fourth or lower order surfaces can be rendered using analytical roots, our adaptive marching points algorithm can ray trace arbitrary implicit surfaces without multiple roots, by sampling the ray at selected points till a root is found. Adapting the sampling step size based on a proximity measure and a horizon measure delivers high speed. The sign test can handle any surface without multiple roots. The Taylor test that uses ideas from interval analysis can ray trace many surfaces with complex roots. Overall, a simple algorithm that fits the SIMD architecture of the GPU results in high performance. We demonstrate the ray tracing of algebraic surfaces up to order 50 and nonalgebraic surfaces including a Blinn's blobby with 75 spheres at better than interactive frame rates.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.41
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.41

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 338
TI Meshless Helmholtz-Hodge Decomposition
A1 Thomas Lewiner,
A1 Afonso Paiva,
A1 Fabiano Petronetto,
A1 Geovan Tavares,
A1 Hélio Lopes,
A1 Marcos Lage,
K1 Helmholtz-Hodge decomposition
K1 smoothed particles hydrodynamics
K1 vector field
K1 features visualization
K1 multiphase fluids
K1 incompressible flow.
AB Vector fields analysis traditionally distinguishes conservative (curl-free) from mass preserving (divergence-free) components. The Helmholtz-Hodge decomposition allows separating any vector field into the sum of three uniquely defined components: curl free, divergence free and harmonic. This decomposition is usually achieved by using mesh-based methods such as finite differences or finite elements. This work presents a new meshless approach to the Helmholtz-Hodge decomposition for the analysis of 2D discrete vector fields. It embeds into the SPH particle-based framework. The proposed method is efficient and can be applied to extract features from a 2D discrete vector field and to multiphase fluid flow simulation to ensure incompressibility.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.61
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.61

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 235
TI Route Visualization Using Detail Lenses
A1 Pushpak Karnick,
A1 Peter Wonka,
A1 Anshuman Razdan,
A1 Stefan Jeschke,
A1 David Cline,
K1 Route visualization
K1 map visualization
K1 overview and detail techniques.
AB We present a method designed to address some limitations of typical route map displays of driving directions. The main goal of our system is to generate a printable version of a route map that shows the overview and detail views of the route within a single, consistent visual frame. Our proposed visualization provides a more intuitive spatial context than a simple list of turns. We present a novel multifocus technique to achieve this goal, where the foci are defined by points of interest (POI) along the route. A detail lens that encapsulates the POI at a finer geospatial scale is created for each focus. The lenses are laid out on the map to avoid occlusion with the route and each other, and to optimally utilize the free space around the route. We define a set of layout metrics to evaluate the quality of a lens layout for a given route map visualization. We compare standard lens layout methods to our proposed method and demonstrate the effectiveness of our method in generating aesthetically pleasing layouts. Finally, we perform a user study to evaluate the effectiveness of our layout choices.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.65
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.65

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 298
TI Origamizing Polyhedral Surfaces
A1 Tomohiro Tachi,
K1 Origami
K1 origami design
K1 developable surface
K1 folding
K1 computer-aided design.
AB This paper presents the first practical method for "origamizing” or obtaining the folding pattern that folds a single sheet of material into a given polyhedral surface without any cut. The basic idea is to tuck fold a planar paper to form a three-dimensional shape. The main contribution is to solve the inverse problem; the input is an arbitrary polyhedral surface and the output is the folding pattern. Our approach is to convert this problem into a problem of laying out the polygons of the surface on a planar paper by introducing the concept of tucking molecules. We investigate the equality and inequality conditions required for constructing a valid crease pattern. We propose an algorithm based on two-step mapping and edge splitting to solve these conditions. The two-step mapping precalculates linear equalities and separates them from other conditions. This allows an interactive manipulation of the crease pattern in the system implementation. We present the first system for designing three-dimensional origami, enabling a user can interactively design complex spatial origami models that have not been realizable thus far.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.67
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.67

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 221
TI Placegram: A Diagrammatic Map for Personal Geotagged Data Browsing
A1 Jung-hee Ryu,
A1 Hyungeun Jo,
K1 Information visualization
K1 graphical user interfaces
K1 spatial databases and GIS
K1 multimedia information systems.
AB Geotagging personal data such as photos and videos are continuously becoming easier and more popular. Nevertheless, browsing such data on general purpose maps can be difficult, due to the frequent zoom and pan operations as well as visual components unnecessary for the task. This paper presents Placegram, a compact diagrammatic map visualization for personal geotagged data browsing based on cognitive map theories. An evaluation using real-life data sets shows that the speed of finding and pointing to places from the participants' own data increased by a factor of 2.1-2.9, and the number of interesting places discovered from others' data within a time limit increased by 48.8 percent in Placegram compared to a general purpose map. Placegram was even slightly faster than a simple text list, while at the same time, preserving the geographic senses of direction and location. Subjective ratings and comments from participants support these results, indicating that Placegram is significantly preferred over both a general map and a text list.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.68
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.68

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2010
VO 16
IS
SP 1
TI Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames
A1 J.B. Bell,
A1 M. Day,
A1 G.H. Weber,
A1 V. Pascucci,
A1 P.-T. Bremer,
K1 Hydrogen
K1 Fires
K1 Isosurfaces
K1 Combustion
K1 Robustness
K1 User interfaces
K1 Computer graphics
K1 Information analysis
K1 Numerical simulation
K1 Statistical distributions
K1 burning regions.
K1 Visualization
K1 data analysis
K1 topological data analysis
K1 Morse complex
K1 Reeb graph
K1 feature detection
K1 feature tracking
K1 combustion simulations
AB This paper presents topology-based methods to robustly extract, analyze, and track features defined as subsets of isosurfaces. First, we demonstrate how features identified by thresholding isosurfaces can be defined in terms of the Morse complex. Second, we present a specialized hierarchy that encodes the feature segmentation independent of the threshold while still providing a flexible multiresolution representation. Third, for a given parameter selection, we create detailed tracking graphs representing the complete evolution of all features in a combustion simulation over several hundred time steps. Finally, we discuss a user interface that correlates the tracking information with interactive rendering of the segmented isosurfaces enabling an in-depth analysis of the temporal behavior. We demonstrate our approach by analyzing three numerical simulations of lean hydrogen flames subject to different levels of turbulence. Due to their unstable nature, lean flames burn in cells separated by locally extinguished regions. The number, area, and evolution over time of these cells provide important insights into the impact of turbulence on the combustion process. Utilizing the hierarchy, we can perform an extensive parameter study without reprocessing the data for each set of parameters. The resulting statistics enable scientists to select appropriate parameters and provide insight into the sensitivity of the results with respect to the choice of parameters. Our method allows for the first time to quantitatively correlate the turbulence of the burning process with the distribution of burning regions, properly segmented and selected. In particular, our analysis shows that counterintuitively stronger turbulence leads to larger cell structures, which burn more intensely than expected. This behavior suggests that flames could be stabilized under much leaner conditions than previously anticipated.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.69
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.69

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 312
TI Robust Feature-Preserving Mesh Denoising Based on Consistent Subneighborhoods
A1 Hanqi Fan,
A1 Qunsheng Peng,
A1 Yizhou Yu,
K1 Denoising
K1 features
K1 clustering
K1 shared nearest neighbors
K1 normals
K1 curvature tensors
K1 quadrics
K1 bilateral filtering.
AB In this paper, we introduce a feature-preserving denoising algorithm. It is built on the premise that the underlying surface of a noisy mesh is piecewise smooth, and a sharp feature lies on the intersection of multiple smooth surface regions. A vertex close to a sharp feature is likely to have a neighborhood that includes distinct smooth segments. By defining the consistent subneighborhood as the segment whose geometry and normal orientation most consistent with those of the vertex, we can completely remove the influence from neighbors lying on other segments during denoising. Our method identifies piecewise smooth subneighborhoods using a robust density-based clustering algorithm based on shared nearest neighbors. In our method, we obtain an initial estimate of vertex normals and curvature tensors by robustly fitting a local quadric model. An anisotropic filter based on optimal estimation theory is further applied to smooth the normal field and the curvature tensor field. This is followed by second-order bilateral filtering, which better preserves curvature details and alleviates volume shrinkage during denoising. The support of these filters is defined by the consistent subneighborhood of a vertex. We have applied this algorithm to both generic and CAD models, and sharp features, such as edges and corners, are very well preserved.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.70
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.70

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 273
TI RACBVHs: Random-Accessible Compressed Bounding Volume Hierarchies
A1 Tae-Joon Kim,
A1 Sung-Eui Yoon,
A1 Bochang Moon,
A1 Duksu Kim,
K1 Hierarchy and BVH compression
K1 random access
K1 cache-coherent layouts
K1 ray tracing
K1 collision detection.
AB We present a novel compressed bounding volume hierarchy (BVH) representation, random-accessible compressed bounding volume hierarchies (RACBVHs), for various applications requiring random access on BVHs of massive models. Our RACBVH representation is compact and transparently supports random access on the compressed BVHs without decompressing the whole BVH. To support random access on our compressed BVHs, we decompose a BVH into a set of clusters. Each cluster contains consecutive bounding volume (BV) nodes in the original layout of the BVH. Also, each cluster is compressed separately from other clusters and serves as an access point to the RACBVH representation. We provide the general BVH access API to transparently access our RACBVH representation. At runtime, our decompression framework is guaranteed to provide correct BV nodes without decompressing the whole BVH. Also, our method is extended to support parallel random access that can utilize the multicore CPU architecture. Our method can achieve up to a 12:1 compression ratio, and more importantly, can decompress 4.2 M BV nodes ({=}135 {\rm MB}) per second by using a single CPU-core. To highlight the benefits of our approach, we apply our method to two different applications: ray tracing and collision detection. We can improve the runtime performance by more than a factor of 4 as compared to using the uncompressed original data. This improvement is a result of the fast decompression performance and reduced data access time by selectively fetching and decompressing small regions of the compressed BVHs requested by applications.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.71
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.71

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 325
TI Real-Time Physics-Based 3D Biped Character Animation Using an Inverted Pendulum Model
A1 Yao-Yang Tsai,
A1 Wen-Chieh Lin,
A1 Tong-Yee Lee,
A1 Jehee Lee,
A1 Kuangyou B. Cheng,
K1 3D human motion
K1 physics-based simulation
K1 biped walk and balance
K1 motion capture data.
AB We present a physics-based approach to generate 3D biped character animation that can react to dynamical environments in real time. Our approach utilizes an inverted pendulum model to online adjust the desired motion trajectory from the input motion capture data. This online adjustment produces a physically plausible motion trajectory adapted to dynamic environments, which is then used as the desired motion for the motion controllers to track in dynamics simulation. Rather than using Proportional-Derivative controllers whose parameters usually cannot be easily set, our motion tracking adopts a velocity-driven method which computes joint torques based on the desired joint angular velocities. Physically correct full-body motion of the 3D character is computed in dynamics simulation using the computed torques and dynamical model of the character. Our experiments demonstrate that tracking motion capture data with real-time response animation can be achieved easily. In addition, physically plausible motion style editing, automatic motion transition, and motion adaptation to different limb sizes can also be generated without difficulty.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.76
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.76

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 287
TI Evolving Mazes from Images
A1 Liang Wan,
A1 Tien-Tsin Wong,
A1 Chi-Sing Leung,
A1 Xiaopei Liu,
K1 Maze
K1 multiscale RD simulator
K1 cellular neural networks
K1 intuitive user controls.
AB We propose a novel reaction diffusion (RD) simulator to evolve image-resembling mazes. The evolved mazes faithfully preserve the salient interior structures in the source images. Since it is difficult to control the generation of desired patterns with traditional reaction diffusion, we develop our RD simulator on a different computational platform, cellular neural networks. Based on the proposed simulator, we can generate the mazes that exhibit both regular and organic appearance, with uniform and/or spatially varying passage spacing. Our simulator also provides high controllability of maze appearance. Users can directly and intuitively “paint” to modify the appearance of mazes in a spatially varying manner via a set of brushes. In addition, the evolutionary nature of our method naturally generates maze without any obvious seam even though the input image is a composite of multiple sources. The final maze is obtained by determining a solution path that follows the user-specified guiding curve. We validate our method by evolving several interesting mazes from different source images.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.85
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.85

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 192
TI Cross-Filtered Views for Multidimensional Visual Analysis
A1 Chris Weaver,
K1 Information visualization
K1 interactive data exploration and discovery
K1 coordinated views
K1 multidimensional visual analysis.
AB Analysis of multidimensional data often requires careful examination of relationships across dimensions. Coordinated multiple view approaches have become commonplace in visual analysis tools because they directly support expression of complex multidimensional queries using simple interactions. However, generating such tools remains difficult because of the need to map domain-specific data structures and semantics into the idiosyncratic combinations of interdependent data and visual abstractions needed to reveal particular patterns and distributions in cross-dimensional relationships. This paper describes: 1) a method for interactively expressing sequences of multidimensional set queries by cross-filtering data values across pairs of views and 2) design strategies for constructing coordinated multiple view interfaces for cross-filtered visual analysis of multidimensional data sets. Using examples of cross-filtered visualizations of data from several different domains, we describe how cross-filtering can be modularized and reused across designs, flexibly customized with respect to data types across multiple dimensions, and incorporated into more wide-ranging multiple view designs. We also identify several important limitations of the approach. The demonstrated analytic utility of these examples suggests that cross-filtering is a suitable design pattern for instantiation in a wide variety of visual analysis tools.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.94
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.94

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 205
TI A Visual Analytics Approach to Understanding Spatiotemporal Hotspots
A1 Ahmad M. Abusalah,
A1 Mohamed Yakout,
A1 Shaun J. Grannis,
A1 William S. Cleveland,
A1 Ryan Hafen,
A1 David S. Ebert,
A1 Mourad Ouzzani,
A1 Stephen Rudolph,
A1 Ross Maciejewski,
K1 Geovisualization
K1 kernel density estimation
K1 syndromic surveillance
K1 hypothesis exploration.
AB As data sources become larger and more complex, the ability to effectively explore and analyze patterns among varying sources becomes a critical bottleneck in analytic reasoning. Incoming data contain multiple variables, high signal-to-noise ratio, and a degree of uncertainty, all of which hinder exploration, hypothesis generation/exploration, and decision making. To facilitate the exploration of such data, advanced tool sets are needed that allow the user to interact with their data in a visual environment that provides direct analytic capability for finding data aberrations or hotspots. In this paper, we present a suite of tools designed to facilitate the exploration of spatiotemporal data sets. Our system allows users to search for hotspots in both space and time, combining linked views and interactive filtering to provide users with contextual information about their data and allow the user to develop and explore their hypotheses. Statistical data models and alert detection algorithms are provided to help draw user attention to critical areas. Demographic filtering can then be further applied as hypotheses generated become fine tuned. This paper demonstrates the use of such tools on multiple geospatiotemporal data sets.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.100
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.100

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2009
VO 16
IS
SP 178
TI Principles and Tools for Collaborative Entity-Based Intelligence Analysis
A1 John W. Bodnar,
A1 Stuart K. Card,
A1 Eric A. Bier,
K1 User interfaces
K1 graphical user interfaces (GUI)
K1 information search and retrieval
K1 information filtering
K1 information systems applications
K1 miscellaneous
K1 group and organization interfaces
K1 collaborative computing
K1 computer-supported cooperative work
K1 Web-based interaction.
AB Software tools that make it easier for analysts to collaborate as a natural part of their work will lead to better analysis that is informed by more perspectives. We are interested to know if software tools can be designed that support collaboration even as they allow analysts to find documents and organize information (including evidence, schemas, and hypotheses). We have modified the Entity Workspace system, described previously, to test such designs. We have evaluated the resulting design in both a laboratory study and a study where it is situated with an analysis team. In both cases, effects on collaboration appear to be positive. Key aspects of the design include an evidence notebook optimized for organizing entities (rather than text characters), information structures that can be collapsed and expanded, visualization of evidence that emphasizes events and documents (rather than emphasizing the entity graph), and a notification system that finds entities of mutual interest to multiple analysts. Long-term tests suggest that this approach can support both top-down and bottom-up styles of analysis.
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2009.104
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2009.104

RT Journal Article
JF IEEE Transactions on Visualization & Computer Graphics
YR 2010
VO 16
IS
SP 177
TI Guest Editor's Introduction: Special Section on the IEEE Symposium on Visual Analytics Science and Technology (VAST)
A1 Thomas Ertl,
K1
PB IEEE Computer Society, [URL:http://www.computer.org]
SN 1077-2626
LA English
DO 10.1109/TVCG.2010.16
LK http://doi.ieeecomputersociety.org/10.1109/TVCG.2010.16