Automatic detection and analysis of discontinuity geometry of rock mass from digital images

The inaccessibility of rock exposures is an inherent problem in geotechnical data acquisition that compromises effective geotechnical evaluation. The digital image processing method is a tool that permits a fast, complete, and accurate acquisition of information. Using digital images in photogrammetry, the present study analyzes the discontinuity geometry of rock mass exposures. The study has demonstrated that (a) the transformation function is appropriate for images without any perspective error; (b) the developed system is versatile and can detect both lines as well as curves in multilinear form; (c) the Hough transform algorithm can provide excellent results for rock mass with multiple joint sets having considerable amount of noise; and (d) the beamlets can be classified in an automated manner. The authors recommend the digital face mapping method to characterize rock masses, as it reduces the time spent in the field, thus preserving data integrity. Furthermore, this technique allows for systematic mapping and the building of a permanent and huge database for rock mass characterization.