Fracture Segmentation Method Based on Contour Evolution and Gradient Direction Consistency in Sequence of Coal Rock CT Images

Zhiwei Li,Guoying Zhang

doi:10.1155/2019/2980747

Abstract

The coal rock exhibits obvious heterogeneity and anisotropy after a long-term geological evolution in nature. Therefore, the coal rock CT (computed tomography) image shows uneven grey scale, low contrast, and the fractures with weak boundaries. The accurate segmentation of the coal rock fracture networks is challenging. In this paper, a segmentation method of fractures based on contour evolution and gradient direction consistency is proposed to accurately segment the fracture networks in the sequence of coal rock CT images. According to the contour variation rule of the fractures in the discrete 3D (three dimensional) space formed by the sequence of CT images, the fracture contour evolution model (FCEM) is constructed and the preliminary segmentation results of fractures are obtained from FCEM. A 3D adaptive median filtering (3DAMF) and a 3D bilateral filtering (3DBF) are proposed. The high density miscellaneous point noises in the coal rock CT images are filtered by the 3DAMF. And the boundaries of fractures are enhanced by 3DBF. According to the similarity of the preliminary segmentation results of fractures and the real contours of fractures, the preliminary segmentation results of fractures are optimized based on the gradient direction consistency model (GDCM) proposed in this paper to obtain the accurate boundaries of fractures. The fracture segmentation method proposed in this paper can obtain accurate boundaries of fractures with weak boundaries, and the experimental results show that the segmentation efficiency for sequence is high and adaptability is strong.

Highlights

With the increase in the depth of the underground coal mining, the gas content in the coal rock increases
A segmentation method of fractures based on contour evolution and gradient direction consistency is proposed to accurately segment the fracture networks in the sequence of coal rock CT images
By studying the 3D grey scale and 3D structure features of fractures in sequence of the coal rock CT images, a fracture segmentation method based on contour evolution and gradient direction consistency is proposed

Summary

Introduction

With the increase in the depth of the underground coal mining, the gas content in the coal rock increases . The fractures with weak boundaries often indicate the most likely change position of the coal rock under mining stress. The segmentation methods of fractures based on 3D features have been widely concerned [10,11,12]. Since these methods can utilize the 3D grey scale and 3D structural features, a higher recognition rate and a lower misjudgement rate are obtained. By studying the 3D grey scale and 3D structure features of fractures in sequence of the coal rock CT images, a fracture segmentation method based on contour evolution and gradient direction consistency is proposed. The gradient direction consistency model (GDCM) is proposed and is used to optimize the preliminary segmentation results of fractures, and the accurate segmentation results of fractures are obtained

Fracture Contour Evolution Model

Gradient Direction Consistency Model

Experimental Results and Analysis

Conclusions