Publications
AniViz: A Template-based Animation Tool for Volume Visualization
Hiroshi Akiba, Chaoli Wang, and Kwan-Liu MaIEEE Computer Graphics and Applications
(accepted for publication)
2009In the communication of scientific studies and findings, animations are often more effective than still images for showing and explaining complex, dynamic processes, relationships, and structures hidden in the data. This paper introduces AniViz - a tool for making visualization animations. The design of AniViz is mainly based on two principles. First, it is desirable to directly turn the results of data exploration and visualization into the content of an animation that displays the most relevant aspects of the data. ...
A Comparison of Gradient Estimation Methods for Volume Rendering on Unstructured Meshes
Carlos Correa, Robert Hero, and Kwan-Liu MaIEEE Transactions for Visualization and Computer Graphics
(Accepted for publication)
2009This paper presents a study of gradient estimation methods for rendering unstructured-mesh volume data. Gradient estimation is necessary for rendering shaded isosurfaces and specular highlights, which provide important cues for shape and depth. Gradient estimation has been widely studied and deployed for regular-grid volume data to achieve local illumination effects, but has been otherwise for unstructured-mesh data. As a result, most of the unstructured-mesh volume visualizations made so far were unlit ...
Proximity-based Visualization of Movement Trace Data
Tarik Crnovrsanin, Chris Muelder, Carlos Correa, and Kwan-Liu MaIn Proceedings of IEEE Symposium on Visual Analytics Science and Technology (VAST 2009)
October, 2009The increasing availability of motion sensors and video cameras in living spaces has made possible the analysis of motion patterns and collective behavior in a number of situations. The visualization of this movement data, however, remains a challenge. Although maintaining the actual layout of the data space is often desirable, direct visualization of movement traces becomes cluttered and confusing as the spatial distribution of traces may be disparate and uneven ...
A Framework for Uncertainty Aware Visual Analytics
Carlos D. Correa, Yu-Hsuan Chan, and Kwan-Liu MaIn Proceedings of IEEE Symposium on Visual Analytics Science and Technology (VAST 2009)
October, 2009Visual analytics has become an important tool for gaining insight on large and complex collections of data. Numerous statistical tools and data transformations, such as projections, binning and clustering, have been coupled with visualization to help analysts understand data better and faster. However, data is inherently uncertain, due to error, noise or unreliable sources. When making decisions based on uncertain data, it is important to quantify and present to the analyst both the aggregated uncertainty of the results and the impact of the sources of that uncertainty ...
code_swarm: A Design Study in Organic Software Visualization
Michael Ogawa and Kwan-Liu MaIEEE Transactions on Visualization and Computer Graphics
(InfoVis 2009)
Volume 15, Number 6, October, 2009This paper is a study of our code swarm application, comprising its design, results and public response. We share our design methodology, including why we chose the organic information visualization technique, how we designed for both developers and a casual audience, and what lessons we learned from our experiment. We validate the results produced by code swarm through a qualitative analysis and by gathering online user comments ...
Visual Analysis of Inter-Process Communication for Large-Scale Parallel Computing
Chris Muelder, Francois Gygi, and Kwan-Liu MaIEEE Transactions on Visualization and Computer Graphics
(InfoVis 2009)
Volume 15, Number 6, October, 2009Abstract—In serial computation, program profiling is often helpful for optimization of key sections of code. When moving to parallel computation, not only does the code execution need to be considered, but also communication between the different processes which can induce delays that are very detrimental to performance. As the number of processes increases, so does the impact of the communication delays on performance ...
The Occlusion Spectrum for Volume Classification and Visualization
Carlos Correa and Kwan-Liu MaIEEE Transactions for Visualization and Computer Graphics
(Visualization 2009 Conference)
Volume 15, Number 6, October, 2009Despite the ever-growing improvements on graphics processing units and computational power, classifying 3D volume data remains a challenge. In this paper, we present a new method for classifying volume data based on the ambient occlusion of voxels. This information stems from the observation that most volumes of a certain type, e.g., CT, MRI or flow simulation, contain occlusion patterns that reveal the spatial structure of their materials or features ...
Curve-Centric Volume Deformation for Comparative Visualization
Ove Daae Lampe, Carlos Correa, Kwan-Liu Ma, and Helwig HauserIEEE Transactions for Visualization and Computer Graphics
(Visualization 2009 Conference)
Volume 16, Number 5, October, 2009We present two visualization techniques for curve-centric volume reformation with the aim is to create compelling comparative visualizations. A curve-centric volume reformation deforms a volume, with regards to a curve in space, to create a new space in which the curve evaluates to zero in two dimensions and spans its arc-length in the third. The volume surrounding the curve is deformed such that spatial neighborhood to the curve is preserved ...
Depicting Time Evolving Flow with Illustrative Visualization Techniques
Wei-Hsien Hsu, Jianqiang Mei, Carlos Correa, and Kwan-Liu MaIn Proceedings of International Conference on Arts & Technology (ArtsIT 2009)
(Best Paper Award)
September, 2009Visualization has become an indispensable tool for scientists to extract knowledge from large amounts of data and convey that knowledge to others. Visualization may be exploratory or illustrative. Exploratory visualization generally provides multiple views of the data at di erent levels of abstraction and should be highly interactive, whereas illustrative visualization is often made offine at high quality with sufficient knowledge about the data and features of interest ...
Social Network Discovery based on Sensitivity Analysis
Tarik Crnovsanin, Carlos Correa, and Kwan-Liu MaIn Proceedings of International Conference on on Advances in Social Networks Analysis and Mining (ASONAM 2009)
July, 2009This paper presents a novel methodology for social network discovery based on the sensitivity coefficients of importance metrics, namely the Markov centrality of a node, a metric based on random walks. Analogous to node importance, which ranks the important nodes in a social network, the sensitivity analysis of this metric provides a ranking of the relationships between nodes. The sensitivity parameter of the importance of a node with respect to another measures the direct or indirect impact of a node ...
Visibility Driven Transfer Functions
Carlos Correa and Kwan-Liu MaIn Proceedings of IEEE Pacific Visualization 2009 Symposium
April, 2009Direct volume rendering is an important tool for visualizing complex data sets. However, in the process of generating 2D images from 3D data, information is lost in the form of attenuation and occlusion. The lack of a feedback mechanism to quantify the loss of information in the rendering process makes the design of good transfer functions a difficult and time consuming task ...
Correlation Study of Time-Varying Multivariate Climate Data Sets
Jeffrey Sukharev, Chaoli Wang, and Kwan-Liu MaIn Proceedings of IEEE Pacific Visualization 2009 Symposium
April, 2009We present a correlation study of time-varying multivariate volumetric data sets. In most scientific disciplines, to test hypotheses and discover insights, scientists are interested in looking for connections among different variables, or among different spatial locations within a data field. In response, we propose a suite of techniques to analyze the correlations in time-varying multivariate data. Various temporal curves are utilized to organize the data and capture the temporal behaviors ...
A Hybrid Space-Filling and Force-Directed Layout Method for Visualizing Multiple-Category Graphs
Takayuki Itoh, Chris Muelder, Kwan-Liu Ma, and Jun SeseIn Proceedings of IEEE Pacific Visualization 2009 Symposium
April, 2009Many graphs used in real-world applications consist of nodes belonging to more than one category. We call such graph ”multiplecategory graphs”. Social networks are typical examples of multiplecategory graphs: nodes are persons, links are friendships, and categories are communities that the persons belong to. It is often helpful
to visualize both connectivity and categories of the graphs simultaneously. In this paper, we present a new visualization technique for multiple-category graphs ...
Interactive Feature Extraction and Tracking by Utilizing Region Coherency
Chris Muelder and Kwan-Liu MaIn Proceedings of IEEE Pacific Visualization 2009 Symposium
April, 2009In this paper, we present a prediction-correction method that uses a prediction step to make the best guess of the feature region in the subsequent time step, followed by growing and shrinking the border of the predicted region to coherently extract the actual feature of interest. This method makes use of the temporal-space coherency of the data to accelerate the extraction process while implicitly solving the tedious correspondence problem that previous methods focus on ...
Next-Generation Visualization Technologies: Enabling Discoveries at Extreme Scale
Kwan-Liu Ma, Chaoli Wang, Hongfeng Yu, Kenneth Moreland, Jian Huang, and Rob RossSciDAC Review
Number 12, February, 2009, pp. 12-21The SciDAC Institute for Ultra-Scale Visualization aims to enable extreme-scale knowledge discovery by advancing the state of visualization technologies, fostering awareness of and communication about new visualization technologies, and placing these technologies into the hands of application scientists. ...
Terascale Direct Numerical Simulations of Turbulent Combustion using S3D
J H Chen, A Choudhary, B de Supinski, M DeVries, E R Hawkes, S Klasky, W K Liao, K-L Ma, J Mellor-Crummey, N Podhorszki, R Sankaran, S Shende, and C S YooComputational Science & Discovery
Volume 2, January-March, 2009Terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. ...