This paper proposes a generic methodology for semi-automatic generation of reliable position annotations for evaluating multi-camera people-trackers on large video datasets. Most of the annotation data is computed automatically, by estimating a consensus tracking result from multiple existing trackers and people detectors and classifying it as either reliable or not. A small subset of the data, composed of tracks with insufficient reliability is verified by a human using a simple binary decision task, a process faster than marking the correct person position. The proposed framework is generic and can handle additional trackers. We present results on a dataset of approximately 6 hours captured by 4 cameras, featuring a person in a holiday flat, performing activities such as walking, cooking, eating, cleaning, and watching TV. When aiming for a tracking accuracy of 60cm, 80% of all video frames are automatically annotated. The annotations for the remaining 20% of the frames were added after human verification of an automatically selected subset of data. This involved about 2.4 hours of manual labour. According to a subsequent comprehensive visual inspection to judge the annotation procedure, we found 99% of the automatically annotated frames to be correct. We provide guidelines on how to apply the proposed methodology to new datasets. We also provide an exploratory study for the multi-target case, applied on existing and new benchmark video sequences.

The current multi-camera systems have not studied the problem of person tracking under low resolution constraints. In this paper, we propose a low resolution sensor network for person tracking. The network is composed of cameras with a resolution of 30×30 pixels. The multi-camera system is used to evaluate probability occupancy mapping and maximum likelihood trackers against ground truth collected by ultra-wideband (UWB) testbed. Performance evaluation is performed on two video sequences of 30 minutes. The experimental results show that maximum likelihood estimation based tracker outperforms the state-of-the-art on low resolution cameras.

Real-time tracking of people has many applications in computer vision, especially in the domain of surveillance. Typically, a network of cameras is used to solve this task. However, real-time tracking remains challenging due to frequent occlusions and environmental changes. Besides, multicamera applications often require a trade-off between accuracy and communication load within a camera network. In this article, we present a real-time distributed multicamera tracking system for the analysis of people in a meeting room. One contribution of the article is that we provide a scalable solution using smart cameras. The system is scalable because it requires a very small communication bandwidth and only light-weight processing on a “fusion center” which produces final tracking results. The fusion center can thus be cheap and can be duplicated to increase reliability. In the proposed decentralized system all low level video processing is performed on smart cameras. The smart cameras transmit a compact high-level description of moving people to the fusion center, which fuses this data using a Bayesian approach. A second contribution in our system is that the camera-based processing takes feedback from the fusion center about the most recent locations and motion states of tracked people into account. Based on this feedback and background subtraction results, the smart cameras generate a best hypothesis for each person. We evaluate the performance (in terms of precision and accuracy) of the tracker in indoor and meeting scenarios where individuals are often occluded by other people and/or furniture. Experimental results are presented based on the tracking of up to 4 people in a meeting room of 9 m by 5 m using 6 cameras. In about two hours of data, our method has only 0.3 losses per minute and can typically measure the position with an accuracy of 21 cm. We compare our approach to state-of-the-art methods and show that our system performs at least as good as other methods. However, our system is capable to run in real-time and therefore produces instantaneous results.