光学遥感影像的山地冰川运动速度分析方法

Mountain Glacier Flow Velocities Analyzed from Satellite Optical Images

山地冰川随着地形、气候变化等因素不断运动,及时准确的获取冰川运动速度是研究山地冰川特性以及冰川灾害预警的重要组成部分.将光学影像相关技术应用于冰川的运动监测,并在运算中提出了"移动格网"方法.选用相同区域时间序列影像,一幅影像上用格网分割冰川区域,每个小单元格在另一幅影像上根据冰川表面纹理特征进行相关分析,取相关性最大的对应单元格作为变化后的位置,两幅图像由单元格位移量计算运动速度.影像上格网逐步移动,直至完成整个冰川区域的速度解算.选用天山区域一块冰川间隔10a的光学影像,对方法进行了验证.

Mountain glaciers are sensitive to environment, of which flow is dependent on topography. It is important to acquire ice flow velocities in time for glacier research and hazard forecast. In this paper, cross-correlating optical imageries are used to monitor ice flow velocities, and an improvement, which is called moving grid, is made to this method. In certain glacier area, two remote sensing images in different times are selected for this research. The first image is divided into grid, and the correlation coefficient of each square in the grid with the square on the second image is calculated. The square with highest correlation coefficient is considered as the counterpart one on the first image. The displacement of the two corresponding squares is the movement of the glacier and it is used to calculate glacier surface velocity. Comparing to the traditional way to divide image with certain grid, this method uses small step to move grid from one location to another adjacent location until the whole glacier area is covered in the image, increasing corresponding point density. A glacier in the Tianshan Mountains is selected for this experiment and two remote sensing images with ten years interval are used to testify this method.