基于正交偏光序列消光特征的岩石薄片颗粒分割与孔隙提取

Grain segmentation and pore identification of multi-angle cross-polarized microscopic images

在岩石薄片正交偏光显微镜下角度域序列图像采集的基础上,分析了不同岩石组分在消光角度域上的光学特征及其差异性,并据此提出一种新的岩石颗粒分割和孔隙分析的方法。充分利用岩石颗粒赋存状态及其晶体光轴产状的复杂性、岩石颗粒空间排列及其接触关系的多样性,对岩石薄片在消光角维度上进行像素尺度的相关分析,并提出相关系数均值、相关系数标准差以及相关系数均差比等敏感参数,实现了岩石颗粒的分割和孔隙的提取。研究表明岩石颗粒内部的像素点灰度和RGB值在角度域上的相关性较强,在颗粒边缘及孔隙内部填隙物分布区域,其相关系数较低,且相关系数标准差要明显高于岩石颗粒内部。该方法从消光特征出发论证了角度域信息完整性的意义,提取的颗粒边缘较为清晰,孔隙结构骨架得以刻画,颗粒分割的效果好于Sobel和Canny等方法。

The optical characteristics and differences of rock components in the thin section were analyzed on the basis of images at sequential extinction angles under the cross-polarized microscope. A new methods for grain segmentation and pore identification were proposed. Taking full advantage of the modes of occurrence of grains and the complexity of crystal optical axis,the spatial arrangement of grains and the diversity of contact relationships,the authors carried out the correlation analysis of pixel scales on the extinction angle of thin sections. The grain segmentation and the pores identification were brought about by sensitive parameters,such as the mean and the standard deviation of the correlation coefficient. The results show that the gray level and RGB values of the pixel inside the grains are more correlated in the angular domain. At the edge of a grain and distribution area of fillings in pores,the correlation coefficient was lower,and the variance of correlation coefficient was obviously higher than that in the interior of grains. This method demonstrates the significance of information integrity in the angle domain from the extinction characteristics. The edge extracted by this method is clear,the skeleton of the pore structure can be characterized,and the accuracy of grain segmentation is better than that of Sobel and Canny.