Structured Models for Videos
Tuesday, December 3rd, 2013 from 12-1 pm in GHC 6501.
Bag of Words is a popular and successful framework for the task of activity classification in videos. In BoW we extract features, cluster them to learn a codebook of words, and then quantize each video by pooling the features. We address limitations of two fundamental aspects of this framework. First, we add structure to the clustering step to enable generalization across different execution styles. Second, we provide a method for pooling features in a structured way. In prior work, this pooling is done over pre-determined rigid cuboids. It is natural to consider pooling features over a video segmentation, but this produces a video representation of variable size. We propose a fixed size representation, Motion Words, where we pool features over supervoxels. To segment the video into supervoxels we propose a superpixel-based method, Globally Consistent Supervoxels, designed to preserve motion boundaries over the entire video. Evaluation on classification and retrieval tasks on two datasets shows that Motion Words achieves state-of-the-art performance. In addition to providing a more flexible support for capturing actions, the proposed method enables interpretation of the results, i.e. it provides understanding of why two videos are similar.
The Student Seminar Series is an informal research seminar by and for SCS graduate students from noon to 1 pm on Tuesdays and Fridays. Lunch is provided by the Computer Science Department (personal thanks to Sharon Burks and Debbie Cavlovich!). At each meeting, a different student speaker will give an informal, 40-minute talk about his/her research, followed by questions/suggestions/brainstorming. We try to attract people with a diverse set of interests, and encourage speakers to present at a very general, accessible level.
So why are we doing this and why take part? In the best case scenario, this will lead to some interesting cross-disciplinary work among people in different fields and people may get some new ideas about their research. In the worst case scenario, a few people will practice their public speaking and the rest get together for a free lunch.
Note: Step #1 below are applicable to all SSS speakers. You can schedule AT MOST THREE talks per semester.
SSS is an ideal forum for SCS students to give presentations that count toward fulfilling their speaking requirements. The specifics, though, vary with each department. For instance, students in CSD will need to be familiar with the notes in Section 8 of the Ph.D. document and follow the instructions outlined on the Speakers Club homepage. Roughly speaking, these are the steps:
Armaghan Naik, Computational Biology