基于GIS的黏性土SEM图像三维可视化与孔隙度计算

黏性土微结构的SEM图像是了解土微结构特征的重要方法，但多数研究仍然以定性分析为主。由于SEM图像在拍摄过程中蕴含了土样中颗粒表面到成像表面的距离信息，因此利用GIS的三维分析模块实现了土样颗粒表面起伏状态的三维显示。利用GIS提供的面积和体积计算方法，分别研究了利用SEM图像计算土样孔隙度的二维和三维方法，并对其进行分析和比较。研究结果显示，基于二维图像处理得到的土样孔隙度受图像处理中阈值的影响较大，阈值越小，图像中颗粒体积越大，土样的孔隙度越小。而基于三维图像处理得到的孔隙度，由于直接采用灰度图像进行计算，得到的孔隙度更加符合实际情况。

3D visualization and porosity computation of clay soil SEM image by GIS

Analyzing the image of SEM of clay soil is a very important method to study the soil microstructure. But most of the traditional method is just qualitative. In fact, there are much information in the image of SEM, for example, the distance from the grain surface to the photographic plate. The authors apply GIS to recreate the three-dimension model of the clay through the SEM image. Also, the method of computing the porosity by GIS technique is introduced, including the two-dimension method and three-dimension method. At last, the analysis and comparison of these two methods are carried out. The result shows that the porosity obtained from two-dimension image (binary image) is affected by the threshold in binarization process, the lower the threshold, the more the volume of the grains, and the lower the porosity. Because the porosity obtained from three-dimension image is gotten directly from the grey-scale image and is not affected by the binarization process, it is more reasonable.