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Events for March 31, 2011
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CS Seminar
Thu, Mar 31, 2011 @ 11:00 AM - 12:00 PM
Thomas Lord Department of Computer Science
Conferences, Lectures, & Seminars
Speaker: Dr. Sven Dickinson, Department of Computer Science, University of Toronto
Talk Title: The Role of Intermediate Shape Priors in Perceptual Grouping and Image Abstraction
Abstract: Perceptual grouping played a prominent role in support of early object recognition systems, which typically took an input image and a database of shape models and identified which of the models was visible in the image. When the database was large, local features were not sufficiently distinctive to prune down the space of models to a manageable number that could be verified. However, when causally related shape features were grouped, using intermediate-level shape priors, e.g., cotermination, symmetry, and compactness, they formed effective shape indices and allowed databases to grow in size. In recent years, the recognition (categorization) community has focused on the object detection problem, in which the input image is searched for a specific target object. Since indexing is not required to select the target model, perceptual grouping is not required to construct a discriminative shape index; the existence of a much stronger object-level shape prior precludes the need for a weaker intermediate-level shape prior. As a result, perceptual grouping activity at our major conferences has diminished. However, there are clear signs that the recognition community is moving from appearance back to shape, and from detection back to unexpected object recognition. Shape-based perceptual grouping will play a critical role in facilitating this transition. But while causally related features must be grouped, they also need to be abstracted before they can be matched to categorical models. In this talk, I will describe our recent progress on the use of intermediate shape priors in segmenting, grouping, and abstracting shape features. Specifically, I will describe the use of symmetry and non-accidental attachment to detect and group symmetric parts, the use of closure to separate figure from background, and the use of a vocabulary of simple shape models to group and abstract image contours.
Biography: Sven Dickinson received the B.A.Sc. degree in Systems Design Engineering from the University of Waterloo, in 1983, and the M.S. and Ph.D. degrees in Computer Science from the University of Maryland, in 1988 and 1991, respectively. He is currently Professor and Chair of the Department of Computer Science at the University of Toronto, where he has also served as Acting Chair (2008-2009), Vice Chair (2003-2006), and Associate Professor (2000-2007). From 1995-2000, he was an Assistant Professor of Computer Science at Rutgers University, where he also held a joint appointment in the Rutgers Center for Cognitive Science (RuCCS) and membership in the Center for Discrete Mathematics and Theoretical Computer Science (DIMACS). From 1994-1995, he was a Research Assistant Professor in the Rutgers Center for Cognitive Science, and from 1991-1994, a Research Associate at the Artificial Intelligence Laboratory, University of Toronto. He has held affiliations with the MIT Media Laboratory (Visiting Scientist, 1992-1994), the University of Toronto (Visiting Assistant Professor, 1994-1997), and the Computer Vision Laboratory of the Center for Automation Research at the University of Maryland (Assistant Research Scientist, 1993-1994, Visiting Assistant Professor, 1994-1997). Prior to his academic career, he worked in the computer vision industry, designing image processing systems for Grinnell Systems Inc., San Jose, CA, 1983-1984, and optical character recognition systems for DEST, Inc., Milpitas, CA, 1984-1985.
Host: Prof. Gerard Medioni
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Kanak Agrawal
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CS Colloquium
Thu, Mar 31, 2011 @ 03:30 PM - 05:00 PM
Thomas Lord Department of Computer Science
Conferences, Lectures, & Seminars
Speaker: Dr. Zhichun Li, NEC Research Labs
Talk Title: Towards Scalable User-Agnostic Attack Defense
Abstract: Security has become one of the major concerns for todayâs Internet. End users, however, are slow in adopting new security technologies. Many users cannot do good security management by themselves. On the other hand, IT managers desire efficient and scalable protection mechanisms.
Towards solving these issues, in this talk, I would like to introduce two of my efforts I did at Northwestern University. First, I will present the design of NetShield, a new vulnerability signature based NIDS/NIPS, which achieves high throughput comparable to that of the state-of-the-art regular expression based systems while offering much better accuracy. In particular, I propose a candidate selection algorithm which efficiently matches thousands of vulnerability signatures simultaneously, and design a parsing transition state machine that achieves fast protocol parsing.
Second, I will talk about WebShield, a secure web proxy design that protects clients from web-based exploits by processing potentially malicious JavaScript in a sandboxed environment (shadow browser) on a middlebox. With shadow browsers, WebShield also aims to deploy client-based defenses against various classes of web attacks without client modifications.
Biography: Zhichun Li currently is a research staff member at NEC Research Labs. Before joining NEC, he received his Ph.D. on Dec 2009 from Northwestern University, and continued working in the same university as a research associate for half a year. He earned both M.S. and B.S. degrees from Tsinghua University in China. His research interests span the areas of security, networking and distributed systems with an emphasis on network security, web security, smartphone security, cloud security, social network security, network measurement and distributed system diagnosis. He has conducted research at Microsoft Research Redmond and International Computer Science Institute (ICSI) of UC Berkeley.
Host: Prof. William Halfond
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Kanak Agrawal
