基于等高线和Fourier-Polar变换的3D地形匹配导航方法

The Novel 3D Terrain Matching Navigation Algorithm Based on Contour Map and Fourier-Polar Transform

一种新的3D地形匹配导航方法。实时地形和参考地形分别用结构简单的等高线表示,地形导航转化为等高线的匹配问题。提出Fourier与Polar变换结合的等高线匹配方法,优点:利用图像整体频谱信息,不需寻找控制点,对一定的噪声和变形具有鲁棒性;Fourier变换易于硬件实现,具有一定的实际应用的优势。实现步骤:在参考等高线图中截取与实时等高线图大小相同的图;利用提出的算法配准这两幅等高线图,获得它们之间的旋转和平移量,从而纠正飞行器飞行姿态。本文理论上证明了构造的旋转平移不变算子的正确性,沙盘地形仿真实验结果表明本文算法具有强的抗噪声和抗变形能力以及高可靠性与精确度,对3D地形辅助导航系统具有重要的理论参考价值。

A novel 3D terrain matching algorithm is presented in this paper. Contour map is utilized to represent the real-time recovered terrain and the aircraft-borne referenced terrain, so the 3D terrain matching is converted to contour matching. Integrating Polar transform into Fourier transform resolves matching problem between real-time contour map and reference contour map, which had the following advantages： it doesn＇t need extracting features, instead it matches the two contour maps in the whole frequency domain which is rotation and translation invariability and is inherently insensitive to random noise and local distortion; Fourier transform is easily hardware realization and has certain superiority in practical application. In this method, intercept the same size map with the real-time contour map in the reference contour map at first, and then the matching of these two maps is carried out by the proposed algorithm which achieves the rotation and translation parameters to correct the flight attitude of aircraft. By way of theoretical analysis and sand-table simulation results, this algorithm is insensitive to noise and distortion, which also has the merits of high reliability and high accuracy, and has important reference value to the practical 3D terrain navigation system.