Exact and Distributed Algorithms for Collaborative Camera Control

We are developing network-based applications for education, journalism, and entertainment where many users share control of a single physical resource. Our latest project, Sharecam, is a single robotic pan, tilt, and zoom digital camera. In this proect we explore algorithms for controlling the camera frame based on independent requests from online users. We propose a metric for the degree of satisfaction for each user and formulate frame selection as an optimization problem. We propose a computational geometry-based algorithm and its distrbuted version. For n users, the algorithm runs in O(n²) time. Its distributed versions run in O(n) time on the client side and in O(n log n) time on the server side.

Figure 1: Sharecam's collaborative camera control interface on the Internet. Each Internet-based user loads two image windows. The lower window is a fixed image of the camera's reachable range of view. Each user requests a camera frame by positioning a dashed rectangle in the lower window. Based on these requests, the algorithm computes an optimal camera frame (shown with solid rectangle), moves the camera accordingly, and displays the resulting live image in the upper window. Requests and camera frames are updated every 10 seconds.
¹Graduate Student (non-EECS)
²Visiting Professor, Utrecht University, The Netherlands
³Professor