New Integrated QDC-2D Toolbox for 2D Discontinuity Abundance Calculation

Quantitative characterisation of the geometrical properties of discontinuities in fractured rock masses is fundamental for understanding their mechanical behaviour, structural characterisation, and for performing reliable rockfall susceptibility assessments. Discontinuity abundance parameters, such as intensity and density, play a key role in rock mass classification and hazard analysis. Yet, accurately estimating them remains challenging due to limited accessibility, scale effects, and censoring bias in conventional field surveys.

Recent advances in remote sensing techniques, particularly UAV-based digital photogrammetry, enable the acquisition of high-resolution three-dimensional point clouds and ortho-view images, commonly referred to as Digital Outcrop Models (DOMs). These datasets significantly improve access to steep or unstable rock faces and enable detailed, reproducible discontinuity mapping. However, standardised, open-source tools for the quantitative analysis of discontinuity abundance from 2D ortho-view images remain limited.

Here, we present a new toolbox within the open-source MATLAB application QDC-2D (Quantitative Discontinuity Characterization, 2D) (Loiotine et al., 2021), focused on the calculation and spatial visualization of discontinuity abundance parameters. The toolbox computes commonly used linear (P10) and areal (P20, P21) discontinuity intensity and density metrics using two approaches. It uses well-established Mauldon estimators (Mauldon et al., 2001) and introduces a circular scan window approach that improves fracture intensity and density estimation through direct calculation of discontinuity trace segment lengths and number within the circular scan window. The toolbox further allows user-defined regions of interest (ROI) and cluster-based abundance calculation to capture spatial variability in discontinuity density and intensity. This approach enables the detection of high-fracturing zones with high certainty.

The toolbox's capabilities have been thoroughly tested and validated using multiple synthetic discontinuity datasets, demonstrating robust, reliable performance. This extension toolbox for QDC-2D provides a reproducible, accessible framework for quantitative discontinuity analysis, thereby supporting improved structural characterisation of fractured rock masses.

 

References:

Mauldon, M., Dunne, W. M., & Rohrbaugh, M. B., Jr. (2001). Circular scanlines and circular windows: New tools for characterizing the geometry of fracture traces. Journal of Structural Geology, 23(2–3), 247–258.

Loiotine, L., Wolff, C., Wyser, E., Andriani, G. F., Derron, M.-H., Jaboyedoff, M., & Parise, M. (2021). QDC-2D: A Semi-Automatic Tool for 2D Analysis of Discontinuities for Rock Mass Characterization. Remote Sensing, 13(24), 5086. https://doi.org/10.3390/rs13245086