用条件滤波法消除航磁图像测线干扰条带

CONDITIONAL FILTERING METHOD TO ELIMINATE INTERFERENCE STRIPES CAUSED BY FLIGHT LINES ON AEROMAGNETIC MAPS

航磁图像网格数据在测线方向上的不稳定，是由于飞行方向的偏离与飞行高度的起伏变化等原因所引起，虽经调平，仍未完全消除，图面上存在残留的条带状干扰，影响对构造形迹的辨认。采用条件滤波法，在调平的基础上，对测线干扰作处理。条件滤波法的要点是：用中位数法，判别干扰条带，仅对条带上的点作滤波；用区间邻点比较法，判别异常极值点，作除外极值点的二维空域滤波。此方法可以改善图像面貌，消除条带，并最大限度地保留有用信息。

Grid data of aerial magnetic image are often unstable along the direction of survey lines,Which are caused by the unstability of the direction and height of the flight.The in terference 3 stripes made difficulty to identify structures.The method that removes the interierences is called conditional filter,Which is designed on the basis of levelling.The core of the conditional filter is as follows:(1)Use of the median value to deternune the pcisition of the stripes,then to filtrate interference peints using a 2-dimensional areal filter or linear interpolation. (2)Filting exclusive of anomalous peaks is proceeded by comparing adjacent points Within an interval to de-termine the position of the anomaious peaks,then to make a 2-dimensional areal filtering. Conditional filter can remove interference stripes and preserve signal to a great extent,and thus improve the feature of image.