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Tushar Athawale is a research scientist at the Computer Science and Mathematics Division of the Oak Ridge National Laboratory (ORNL) in the visualization group led by Dr. Dave Pugmire . His primary research interests are in uncertainty quantification and statistical analysis for scientific data discovery. He was a postdoctoral fellow at the University of Utah's Scientific Computing & Imaging (SCI) Institute from Oct, 2016 - Oct, 2021 with Prof. Chris R. Johnson as his advisor. He received PhD in Computer Science from the University of Florida in May, 2015, and he worked with Prof. Alireza Entezari while pursuing his PhD. He was a full-time employee at MathWorks, the developer of the leading computing software MATLAB, before joining the SCI Institute.

PhD Dissertation:

Quantification and Visualization of Spatial Uncertainty in Isosurfaces for Parametric and Nonparametric Noise Models

T. M. Athawale
 [PhD dissertation preprint] [BibTex] [PhD defense presentation slides] [Proposal presentation slides] (University of Florida, ProQuest Dissertations Publishing, 2015)
Defense committee: Dr. Alireza Entezari (Chair), Dr. Arunava Banerjee, Dr. Anand Rangarajan, Dr. Manuel Bermudez, and Dr. Haldun Aytug (External)
Abstract

Isosurfaces are the key entities in visualization, and recent research has focused on the visualization of uncertain data. We study positional uncertainty in isosurfaces when data uncertainty is modeled with parametric and nonparametric density models. Noise in sampled data leads to topological and geometric variations in the extracted isosurface. We propose probabilistic techniques that reduce topological uncertainty in isosurfaces and resolve ambiguities in identifying topological configurations. We also characterize, in closed form, a random variable modeling the geometric uncertainty in isosurface extraction. Closed-form characterization of geometric uncertainty allows analytic computation of expected value of level-crossing location, as well as the variance. While former quantity can be used for constructing a stable isosurface for uncertain data, the latter can be used for visualizing the spatial uncertainty in the extracted isosurface. We show computational advantage of proposed analytic approach over expensive Monte-Carlo sampling approach for quantifying geometric uncertainty. The advantages of nonparametric statistical models over parametric noise models for uncertainty characterization are evident from our experiments on ensemble datasets and uncertain scalar fields. We also propose a novel approach that leverages nonlocal statistics for accurate characterization of underlying uncertainties in the nonparametric framework.
 

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