Research Of Key Technology In Passive Ranging Based On Image Information

How to estimate the distance from a target to the camera is a technology problem, which rather difficult but has importance value both in military affairs and in civil affairs. In this paper, a schema was proposed for estimating the distance from a target to the imaging camera based on characteristic linearity. According to the schema, the relative distance variation or the distance ratio could be obtained from the image matching, with the target's azimuth, pitching, and coordinates of camera involved, the distance from an imaged target to the camera could turn out by solving the ranging equations. It was proved that the relative distance variation or the distance ratio dominates the ranging error, therefore, how to obtain a more accurate distance ratio become the key technology in this ranging schema.By analyzing and comparing the target's in the sequence image, and taking into account the real-time realizing requirement, we establish such a research steps witch begins with the corn features detection using the Harris operator, and the relative distance variation or the distance ratio could be obtained based on key points matching. It performed a target's corn features detection based on Harris operator in Visual C++ 6.0 code, in the mean time, it studied the relation of the corn features via the Harris'threshold, and some data obtained that would be benefit to further research. In our research, a digital simulation was developed for investigating target's characteristic linearity error via the key points key point extraction, this is valuable to practical image matching. At last, it matched the two adjacent frames image through the Local area correlation coefficient, consequently, we got the characteristic linearity and the distance ratio. It is showed by preliminary experiments that this algorithm could achieve a distance ratio with the error less than±10%.The method is valid for a monocular sequence imaging to a moving target, it might have some value to the passive ranging based on imaging test.