AUTOMATIC ORIENTATION ANALYSIS OF PARTICLES OF SOIL MICROSTRUCTURES

In studying soil microstructure, the orientations of soil particles and of the voids between them are two of the most important factors. In this Paper, the directed vein method and the convex hull method are proposed for automatic orientation analysis of soil microstructure. In the directed vein method a directed vein image of the boundaries of the particles in an electron micrograph of soil structure is constructed using a chain code, and the expected directions of a directed vein are calculated to provide the orientation of the vein. In the convex hull method simple polygons are constructed from the boundaries, the convex hulls of the simple polygons are built up, and the longest diagonal of each convex hull is selected, the direction of which is taken as the orientation of the particle. Before either method can be applied, image preprocessing must be carried out to find the boundaries of the particles. Both methods involve simpler programming, faster computing and less storage than do other methods.