Automatic extraction of blocks from 3D point clouds of fractured rock

Na Chen, John Kemeny, Qinghui Jiang, Zhiwen Pan

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


This paper presents a new method for extracting blocks and calculating block size automatically from rock surface 3D point clouds. Block size is an important rock mass characteristic and forms the basis for several rock mass classification schemes. The proposed method consists of four steps: 1) the automatic extraction of discontinuities using an improved Ransac Shape Detection method, 2) the calculation of discontinuity intersections based on plane geometry, 3) the extraction of block candidates based on three discontinuities intersecting one another to form corners, and 4) the identification of “true” blocks using an improved Floodfill algorithm. The calculated block sizes were compared with manual measurements in two case studies, one with fabricated cardboard blocks and the other from an actual rock mass outcrop. The results demonstrate that the proposed method is accurate and overcomes the inaccuracies, safety hazards, and biases of traditional techniques.

Original languageEnglish (US)
Pages (from-to)149-161
Number of pages13
JournalComputers and Geosciences
StatePublished - Dec 2017


  • 3D point clouds
  • Automatic extraction
  • Block size
  • Discontinuity orientation
  • Rock mass

ASJC Scopus subject areas

  • Information Systems
  • Computers in Earth Sciences


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