2009 Fiscal Year
International Academic Journals
Applying manifold learning to plotting approximate contour trees
IEEE Transactions on Visualization and Computer Graphics, Vol. 15, No. 6 (Special Issue of IEEE VisWeek 2009), pp. 1185-1192, November/December 2009 [DOI:].
A contour tree is a powerful tool for delineating the topological evolution of isosurfaces of a single-valued function, and thus has been frequently used as a means of extracting features from volumes and their time-varying behaviors. Several sophisticated algorithms have been proposed for constructing contour trees while they often complicate the software implementation especially for higher-dimensional cases such as time-varying volumes. This paper presents a simple yet effective approach to plotting in 3D space, approximate contour trees from a set of scattered samples embedded in the high-dimensional space. Our main idea is to take advantage of manifold learning so that we can elongate the distribution of high-dimensional data samples to embed it into a low-dimensional space while respecting its local proximity of sample points. The contribution of this paper lies in the introduction of new distance metrics to manifold learning, which allows us to reformulate existing algorithms as a variant of currently available dimensionality reduction scheme. Efficient reduction of data sizes together with segmentation capability is also developed to equip our approach with a coarse-to-fine analysis even for large-scale datasets. Examples are provided to demonstrate that our proposed scheme can successfully traverse the features of volumes and their temporal behaviors through the constructed contour trees.
International Conference Proceedings
Topologically-based haptization and visualization of wake turbulence datasets
in DVD Proceedings of IIEEJ IEVC2010, Nice (France), March 2010
To control aircraft landing and takeoff effectively, it is important to analyze the collapse process of relevant wake turbulence. In this paper, we propose a topologically-based multisensory realization method that allows observers to comprehend the behavior of wake turbulence phenomena more intuitively. To this end, we design visual transfer functions with reference to a time-varying critical point histogram, as well as 4 DOF haptic transfer functions for producing two-dimensional forces and torques so as to identify the location and strength of a target vortex in real time. The effectiveness of our method is evaluated with a time-varying two-dimensional wake turbulence dataset calculated by measurement-integrated simulation.
Feature-driven volume fairing
in Proceedings of Smart Graphics 2009, Vol. 5531, pp. 233-242, Salamanca (Spain), May 2009
Volume datasets have been a primary representation for scientific visualization with the advent of rendering algorithms such as marching cubes and ray casting. Nonetheless, illuminating the underlying spatial structures still requires careful adjustment of visualization parameters each time when a different dataset is provided. This paper introduces a new framework, called feature-driven volume fairing, which transforms any 3D scalar field into a canonical form to be used as communication media of scientific volume data. The transformation is accomplished by first modulating the topological structure of the volume so that the associated isosurfaces never incur internal voids, and then geometrically elongating the significant feature regions over the range of scalar field values. This framework allows us to elucidate spatial structures in the volume instantly using a predefined set of visualization parameters, and further enables data compression of the volume with a smaller number of quantization levels for efficient data transmission.
International Conference Posters (Peer-Reviewed)
Interpolating 3D diffusion ten-sors through optimizing rotational transformations of anisotropic features
in Poster Proceedings of IEEE Pacific Visualization Symposium 2010, Taipei, March 3, 2010, pp. 3–4
Realizing scalable visu-alization through hierarchical provenance management
in Proceedings of Ninth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration, Sendai, November 5, 2009
Topologically-accentuated realization of wake turbulence datasets
in Proceedings of Ninth International Symposium on Advanced Fluid Information and Transdisci-plinary Fluid Integration, Sendai, November 5, 2009