基于无穷单应阵的动态天基弱小目标检测

Dim small target detection under dynamic sky background based on homography matrix

提出了一种基于无穷单应矩阵抑制动态天基背景的方法,为动态天基背景下的弱小运动目标检测提供了新思路。与以往方法不同,对于由成像卫星运动而造成运动的高频恒星背景,该方法首先利用惯性坐标系下成像卫星姿态及位置的变化,确定卫星平台运动对恒星成像的影响;然后,根据相机对无穷远点的成像原理,计算出不同时刻图像之间的单应矩阵以补偿背景恒星的运动;利用改进的中值滤波抑制低频地球背景,并结合三维时空方向滤波和卡尔曼预测实现对弱小目标的检测与稳定跟踪。实验结果表明,算法能对背景恒星运动准确补偿,抑制背景的效果(图像信噪比增益和背景抑制因子)为传统方法两倍以上,在背景抑制后对弱小目标进行有效检测,定位误差可稳定在半个像素以内。

A method based on homography matrix is proposed to remove dynamic sky background,which provides a new approach to detect small target under dynamic sky background. The movement and rotation of satellite can cause the movement and rotation of camera,which have an influence on the imaging of stars,so the homography matrix between different moments was calculated according to the rotation matrix of satellite and the imaging principle of camera on infinity points,and the movement of star background can be removed by this homography. Then,median filter is utilized to suppress earth background. Lastly,three dimensional space-time directional filter combining with Kalman filter is applied to detect and track small targets. The experimental results show that the proposed method can effectively restrain the background,and target positioning accuracy is less than half pixel.