A semi-automated methodology for rock mass discontinuity trace map construction

The data obtained from rock mass discontinuity traces are used as significant parameters for rock engineering projects. The methodology of documenting discontinuity orientations by photogrammetry has the advantages of non-contact, fast, safe, and high precision measurement. The discontinuity trace detection and recognition is the key technology. In this paper, a new discontinuity trace detection methodology is presented based on line detection and segmentation traces´ semi-automated linking. This methodology considers a rock mass exposure digital image as a discrete surface, the elevation of which is given by pixel brightness levels. The discontinuity trace line feature is automatically detected by using a line detection algorithm based on Hessian matrix to extract the curvilinear structure of the digital image. The discontinuity trace map is constructed by selecting the seed pixel in the line segment map and linking the line segments interpretatively. The experimental results show that this paper´s methodology can be used in processing digital images of rock exposures from underground caverns and open environments. The trace map constructed by the new methodology is mainly consistent with a map drawn manually. These results demonstrate the effectiveness of the proposed methodology.