采用加速稳健特征对侧扫声呐图像进行分块弹性镶嵌

Elastic Mosaic Method in Block for Side-Scan Sonar Image Based on Speeded-Up Robust Features

拖曳式侧扫声呐图像沿航迹方向存在类型和大小不断变化的局部畸变,造成条带图像镶嵌时共视目标扭曲和错位。为了实现公共区域融合后目标的保形性,提出了一种基于加速稳健特征（speeded-up robust features,SURF）的分块弹性镶嵌方法。该方法通过对相邻条带重叠区域自动分块提取特征、整体刚性变换、局部薄板样条弹性变换等处理,既可消除相邻条带图像间的系统性位置和航向偏差,又能消弱各处随机性局部畸变,从而实现共视目标的特征级保形镶嵌。实验结果表明,特征点对整体配准精度达到2个像素,验证了该方法的有效性。

The side-scan sonar towed working mode leads to changing local distortion in types and magnitude along the track,and further results in features＇ disposition and distortion in mosaic image.In order to guarantee clarity edge of the local features in overlap region of adjacent images,this paper proposes an elastic blocking mosaic method based on speeded-up robust features.Firstly,combining with the information of track line and swath,each stripe image can be sliced to several blocks.Then the SURF image registration is done in each block including features extraction,matching and refining.With the registration point-pairs between blocks from adjacent stripe image,a rigid transformation in global image and a series of elastic transformation in each block image can be done.The method not only eliminates systematic errors of position and heading between two adjacent side-scan sonar images,but also weakens random local distortion and achieves high-accurate registration in local area by corresponding features.At last,the experiment demonstrates the validity of this method,the overall registration accuracy reaches two pixels.