[4] T.R. Reid, J. P Hanison. A semi-automated methodology for dis- continuity trace detection in digital images of rock mass exposures [J]. International Journal of Rock Mechanics&Minim Sciences 2000(37): 1073-1089.
[5] R.Lemy J. Hadjigeorgiou. Discontinuity trace map construction using photographs of rock exposures [J]. International Journal of Rock Mechanics&Mining Sciences, 2003(40): 903-917.
[6] Sou-Sen LeuT, Shiu-Lin Chang. Digital image Processing based approach for tunnel excavation faces[J].Automation in Construc- tion.2005, 14:750-765.