Archived Weekly Agendas for Spring 2010
From Utah Center for Neuroimage Analysis
Contents |
Dates
January 25
Jeff Phillips
Algorithms for the Current Distance
The "current distance" was introduced by Vaillant and Glaunes as a way of comparing shapes (point sets, curves, surfaces) without having to rely on computing correspondences between features in each shape. This distance measure is defined by viewing a shape as a linear operator on a k-form field, and constructing a (dual) norm on the space of shapes. As formulated, it takes O(nm) time to compute the current distance between two shapes of size n and m, and there are no known algorithms to compute the current distance between shapes minimized under transformation groups. In this paper, we provide the first algorithmic analysis of the current distance. Our main results are (i) a method for computing the approximate current distance between two shapes in near-linear time, (ii) a coreset construction that allows us to approximate the current norm of a shape using a constant-sized sample, and (iii) an approximation algorithm for computing the current distance between two d-dimensional shapes under rigid transformations (rotations and translations).
An interesting aspect of our work is that we can compute the current distance between curves, surfaces, and higher-order manifolds via a simple reduction to instances of weighted point sets, thus obviating the need for different kinds of algorithms for different kinds of shapes.
joint work w/ Sarang Joshi, Raj Varma Kammaraju, and Suresh Venkatasubramanian
February 1
Adam Bolton, Department of Physics and Astronomy, University of Utah
"Massive Astronomical Survey Spectroscopy"
Abstract: The Baryon Oscillation Spectroscopic Survey (BOSS) is an astronomical project to map the three-dimensional distribution of massive galaxies and intergalactic gas over a larger volume of the universe than any other survey to date, with the University of Utah as a major institutional partner. The core scientific goal of BOSS is to measure the clustering properties of matter on the largest scales in the universe, and to thereby constrain the nature of the "dark energy" that is believed to drive the present-day expansion of the universe. To accomplish this goal, BOSS uses a 54-CCD imaging camera and custom 1000-fiber optical spectrograph on the dedicated 2.5-meter Sloan Digital Sky Survey (SDSS) telescope in Apache Point, NM. In this presentation, I will describe the survey science, hardware, and operations. I will focus significant attention on the image-processing challenges that we face in attempting to make the most accurate reconstruction of astronomical stimuli from CCD detector responses. If time permits, I will also describe an additional scientific project using the SDSS and BOSS databases to discover and study new examples of the strong gravitational lens effect.
February 8
Antonio
February 15 - no image lunch president's day
February 22
Yongsheng Pan
A presentation on backscatter simulator and iterative reconstruction using SART from the simulated projection data
Linh Khanh Ha
CUDA CompOnc library and the implementation with atlas building
March 1
Review of SPIE
Neda Sadeghi
Yongsheng Pan
