Kalman filters for audio-video source localization

In prior work, we proposed using an extended Kalman filter to directly update position estimates in a speaker localization system based on time delays of arrival. We found that such a scheme provided superior tracking quality as compared with the conventional closed-form approximation methods. In this work, we enhance our audio localizer with video information. We propose an algorithm to incorporate detected face positions in different camera views into the Kalman filter without doing any explicit triangulation. This approach yields a robust source localizer that functions reliably both for segments wherein the speaker is silent, which would be detrimental for an audio only tracker, and wherein many faces appear, which would confuse a video only tracker. We tested our algorithm on a data set consisting of seminars held by actual speakers. Our experiments revealed that the audio-video localizer functioned better than a localizer based solely on audio or solely on video features.