(A more complete list can be seen at DBLP.)


Using Global Illumination in Volume Visualization of Rheumatoid Arthritis CT Data

Lin Zheng, Abhijit Chaudhari, Ramsey Badawi, and Kwan-Liu Ma

IEEE Computer Graphics and Applications
Volume 34, Number 6, December, 2014, pp. 16-23

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Proper lighting in rendering is essential for visualizing 3D objects, but most visualization software tools still employ simple lighting models. The advent of hardware-accelerated advanced lighting suggests that volume visualization can be truly usable for clinical work. Researchers studied how volume rendering incorporating global illumination impacted perception of bone surface features captured by x-ray computed-tomography scanners for clinical monitoring of rheumatoid arthritis patients ...


Interactive Progressive Visualization with Space-Time Error Control

Steffen Frey, Filip Sadlo, Kwan-Liu Ma, and Thomas Ertl

IEEE Transactions on Visualization and Computer Graphics
(SciVis 2015)
Volume 20, Number 12, December, 2014, pp. 2397-2406

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We present a novel scheme for progressive rendering in interactive visualization. Static settings with respect to a certain image quality or frame rate are inherently incapable of delivering both high frame rates for rapid changes and high image quality for detailed investigation. Our novel technique flexibly adapts by steering the visualization process in three major degrees of freedom: when to terminate the refinement of a frame in the background and start a new one, when to display a frame currently computed, and how much resources to consume ...


Trajectory-Based Flow Feature Tracking in Joint Particle/Volume Datasets

Franz Sauer, Hongfeng Yu, and Kwan-Liu Ma

IEEE Transactions on Visualization and Computer Graphics
(SciVis 2015)
Volume 20, Number 12, December, 2014, pp. 2565-2574

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Studying the dynamic evolution of time-varying volumetric data is essential in countless scientific endeavors. The ability to isolate and track features of interest allows domain scientists to better manage large complex datasets both in terms of visual understanding and computational efficiency. This work presents a new trajectory-based feature tracking technique for use in joint particle/volume datasets. While traditional feature tracking approaches generally require a high temporal resolution, this method utilizes the indexed trajectories of corresponding Lagrangian particle data to efficiently track features over large jumps in time ...


Visual Abstraction and Exploration of Multi-class Scatterplots

Haidong Chen, Wei Chen, Honghui Mei, Zhiqi Liu, Kun Zhou, Weifeng Chen, Wentao Gu, and Kwan-Liu Ma

IEEE Transactions on Visualization and Computer Graphics
(SciVis 2014)
Volume 20, Number 12, November, 2014, pp. 1683-1692

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Scatterplots are widely used to visualize scatter dataset for exploring outliers, clusters, local trends, and correlations. Depicting multi-class scattered points within a single scatterplot view, however, may suffer from heavy overdraw, making it inefficient for data analysis. This paper presents a new visual abstraction scheme that employs a hierarchical multi-class sampling technique to show a feature-preserving simplification. To enhance the density contrast, the colors of multiple classes are optimized by taking the multi-class point distributions into account ...


Volume Rendering of Curvilinear-Grid Data Using Low-Dimensional Deformation Textures

Robert Hero, Chris Ho, and Kwan-Liu Ma

IEEE Transactions on Visualization and Computer Graphics
Volume 20, Number 9, September, 2014, pp. 1330-1343

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In this paper, we present a high quality and interactive method for volume rendering curvilinear-grid data sets. This method is based on a two-stage parallel transformation of the sample position into intermediate computational space then into texture space through the use of multiple 1 and 2D deformation textures using hardware acceleration. In this manner, it is possible to render many curvilinear-grid volume data sets at high quality and with a low memory footprint, while taking advantage of modern graphic hardware’s tri-linear filtering for the data itself ...


Object Movements Synopsis via Part Assembling and Stitching

Yongwei Nie, Hanqiu Sun, Ping Li, Chunxia Xiao, and Kwan-Liu Ma

IEEE Transactions on Visualization and Computer Graphics
Volume 20, Number 9, September, 2014, pp. 1303-1315

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Video synopsis aims at removing video\'s less important information, while preserving its key content for fast browsing, retrieving, or efficient storing. Previous video synopsis methods, including frame-based and object-based approaches that remove valueless whole frames or combine objects from time shots, cannot handle videos with redundancies existing in the movements of video object. In this paper, we present a novel part-based object movements synopsis method, which can effectively compress the redundant information of a moving video object and represent the synopsized object seamlessly ...


Regression Cube: A Technique for Multidimensional Visual Exploration and Interactive Pattern Finding

Yu-Hsuan Chan, Carlos D. Correa, and Kwan-Liu Ma

ACM Transactions on Interactive Intelligent Systems (TiiS)
(Special Issue on Interactive Computational Visual Analytics)
Volume 4, Number 1, April, 2014, pp. Article No. 7

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Scatterplots are commonly used to visualize multidimensional data; however, 2D projections of data offer limited understanding of the high-dimensional interactions between data points. We introduce an interactive 3D extension of scatterplots called the Regression Cube (RC), which augments a 3D scatterplot with three facets on which the correlations between the two variables are revealed by sensitivity lines and sensitivity streamlines. The sensitivity visualization of local regression on the 2D projections provides insights about the shape of the data through its orientation and continuity cues ...


Fast Closed-Form Matting Using a Hierarchical Data Structure

Chunxia Xiao, Meng Liu, Donglin Xiao, Zhao Dong, and Kwan-Liu Ma

IEEE Transactions on Circuits and Systems for Video Technology
Volume 24, Number 1, January, 2014, pp. 49-62

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Image/video matting is one of the key operations in many image/video editing applications. Although previous methods can generate high-quality matting results, their high computational cost in processing high-resolution image and video data often limits their usability. In this paper, we present a unified acceleration method for closed-form image and video matting using a hierarchical data structure, which achieves an excellent compromise between quality and speed ...