Active contours and optical flow for automatic tracking of flying vehicles

Abstract

In this paper, we describe fast implementations of optical flow and geometric active contours to reliably track flying vehicles. Given the position of the vehicle at time t -1, optical flow information is used to initially place an active contour in the basin of attraction of a region of interest in a given dynamical image at time t. For real-time tracking, fast convergence of the active contour as wen as rapid computation of the optical flow are crucial. In this note, we will describe algorithms that make fast tracking possible in this framework using only standard computing platforms.

Vision-Based Tracking of Uncooperative Targets

“…An ownship navigation filter and a flight guidance and control system have already been developed and implemented [9]. The image processor used is developed for realtime target tracking by Ha et al [10,11]. In flight experiments, closedloop vision-based formation flights of two UAVs have been successfully achieved [12].…”

“…This paper will address only the tracking and estimation part of the problem. The particular image processing algorithms used in our application are described in [6].…”

“…Additionally, as long as the difference between the camera and target pitch angles is small, there will be no ambiguity between pitch and roll orientation of the target. The image processor developed in [10] tracks the target's contour in images, and can thus extract the target size. Figure 2 shows an example of the image tracking result.…”

“…Image processing techniques are based on [6] and extended to use the Fast Level Set Marching Method [7] for computational speed. Section 3 provides the Extended Kalman Filter formulation for the navigation problem where image processing is able to provide subtended angle information.…”

“…The EKF prediction and update procedures discussed in the Appendix are applied to the process and measurement models given in (10) and (14).…”