Passive Range Estimation Using Two and Three Optical Cameras

Abstract

In passive tracking of a flying object with bearing only measurements, range information is needed. This is accomplished by applying more than one passive optical imager. Active sensing systems have disadvantages for low-flying targets in cluttered backgrounds meanwhile are simply detected. In the observable regions of the target range, using two cameras, target range can be calculated by triangulation. If the target locates in the vicinity of sensors baseline, low observable target range will be resulted. This problem can be solved using three cameras. In this paper novel equations to calculate the target range using 3-D triangulation by two cameras are extracted, observability condition for target range is stated, target range is estimated by extended Kalman filter, observable target range is resulted by using three bearing sensors placed at a distance not along a straight line, and finally sensor fusion for estimated target range is performed.