Research on Image Motion Compensation of an Airborne Camera with a Focal Plane Charge-Coupled Device Camera and an Analysis of Image Motion

Abstract

The imaging quality of a target is dramatically influenced by image motion (IM), which results from the relative movement between a charge-coupled device (CCD) camera and an aircraft during the exposure time. Therefore, it is quite necessary to produce appropriate systems to compensate for this kind of movement and achieve high-quality, real-time imaging. The image motion velocity should be precisely calculated to compensate for the image motion as much as possible. In the paper, several methods were introduced to calculate the image motion velocity by using coordinate transformation, which deduced the image motion value of a given point by considering the difference before and after the gesture angles and position changes. Furthermore, both a theoretical and a mechanical image motion compensation (IMC) method were analyzed. A three-axis stable platform was assembled between the camera system and the unmanned aircraft. The IM caused by variation in the airplane gesture angles, including the pitch angle, yaw angle and roll angle, could be compensated by the reverse rotation of the stable platform in the corresponding axis. Similarly, the IM caused by the aircraft’s continuing flight could be compensated by the reverse rotation in the pitch axis. The residual errors of the IMC of the camera from the aircraft navigation were analyzed and calculated in detail. The residual errors of the image points were less than one third of the diameter of a CCD pixel, which demonstrates that the IMC system satisfied the imaging system.