Tracking a Large Number of Objects from Multiple Views

We propose a multi-object multi-camera framework for tracking large numbers of tightly-spaced objects that rapidly move in three dimensions. We formulate the problem of finding correspondences across multiple views as a multidimensional assignment problem and use a greedy randomized adaptive search procedure to solve this NP-hard problem efficiently. To account for occlusions, we relax the one-to-one constraint that one measurement corresponds to one object and iteratively solve the relaxed assignment problem. After correspondences are established, object trajectories are estimated by stereoscopic reconstruction using an epipolar-neighborhood search. We embedded our method into a tracker-to-tracker multi-view fusion system that not only obtains the three-dimensional trajectories of closely-moving objects but also accurately settles track uncertainties that could not be resolved from single views due to occlusion. We conducted experiments to validate our greedy assignment procedure and our technique to recover from occlusions. We successfully track hundreds of flying bats and provide an analysis of their group behavior based on 150 reconstructed 3D trajectories.

Singing Through Struggle: Music as a Mode of Cultural Exchange in African American Border City Churches After Emancipation, 1862-1890

This project investigates how religious music, invested with symbolic and cultural meaning, provided African Americans in border city churches with a way to negotiate conflict, assert individual values, and establish a collective identity in the post- emancipation era. In order to focus on the encounter between former slaves and free Blacks, the dissertation examines black churches that received large numbers of southern migrants during and after the Civil War. Primarily a work of history, the study also employs insights and conceptual frameworks from other disciplines including anthropology and ritual studies, African American studies, aesthetic theory, and musicology. It is a work of historical reconstruction in the tradition of scholarship that some have called "lived religion." Chapter 1 introduces the dissertation topic and explains how it contributes to scholarship. Chapter 2 examines social and religious conditions African Americans faced in Baltimore, MD, Philadelphia, PA, and Washington, DC to show why the Black Church played a key role in African Americans' adjustment to post-emancipation life. Chapter 3 compares religious slave music and free black church music to identify differences and continuities between them, as well as their functions in religious settings. Chapters 4, 5, and 6 present case studies on Bethel African Methodist Episcopal Church (Baltimore), Zoar Methodist Episcopal Church (Philadelphia), and St. Luke’s Protestant Episcopal Church (Washington, DC), respectively. Informed by fresh archival materials, the dissertation shows how each congregation used its musical life to uphold values like education and community, to come to terms with a shared experience, and to confront or avert authority when cultural priorities were threatened. By arguing over musical choices or performance practices, or agreeing on mutually appealing musical forms like the gospel songs of the Sunday school movement, African Americans forged lively faith communities and distinctive cultures in otherwise adverse environments. The study concludes that religious music was a crucial form of African American discourse and expression in the post-emancipation era. In the Black Church, it nurtured an atmosphere of exchange, gave structure and voice to conflict, helped create a public sphere, and upheld the values of black people.

A Two-Tiered On-Line Server-Side Bandwidth Reservation Framework for the Real-Time Delivery of Multiple Video Streams

The advent of virtualization and cloud computing technologies necessitates the development of effective mechanisms for the estimation and reservation of resources needed by content providers to deliver large numbers of video-on-demand (VOD) streams through the cloud. Unfortunately, capacity planning for the QoS-constrained delivery of a large number of VOD streams is inherently difficult as VBR encoding schemes exhibit significant bandwidth variability. In this paper, we present a novel resource management scheme to make such allocation decisions using a mixture of per-stream reservations and an aggregate reservation, shared across all streams to accommodate peak demands. The shared reservation provides capacity slack that enables statistical multiplexing of peak rates, while assuring analytically bounded frame-drop probabilities, which can be adjusted by trading off buffer space (and consequently delay) and bandwidth. Our two-tiered bandwidth allocation scheme enables the delivery of any set of streams with less bandwidth (or equivalently with higher link utilization) than state-of-the-art deterministic smoothing approaches. The algorithm underlying our proposed frame-work uses three per-stream parameters and is linear in the number of servers, making it particularly well suited for use in an on-line setting. We present results from extensive trace-driven simulations, which confirm the efficiency of our scheme especially for small buffer sizes and delay bounds, and which underscore the significant realizable bandwidth savings, typically yielding losses that are an order of magnitude or more below our analytically derived bounds.