LAUSR

Abstract Advances in estimating the three-dimensional (3D) orientation distribution include i) the stereology-based Fouche estimator (FE); and ii) its recent modification (MFE), which has one less meshing step and has three modified components compared with the FE. One way to achieve an accurate estimate is by selecting the optimum estimator. Here, we developed a recognizer for the optimum estimator to help automatically select the most likely accurate estimator for use in the FE and MFE. Before this, we conducted a systematic comparison of the likelihood of obtaining an accurate estimation to clarify for which patterns FE and MFE are likely to perform accurately. The statistical comparison results showed that the MFE was more likely to perform accurately than the FE for patterns of moderately to strongly aligned fracture sets and for patterns of poorly aligned fracture sets with medium to wide intersection angles to the 1D probe, and thus, the MFE was the optimum estimator. For patterns of poorly aligned fracture sets with narrow intersection angles to the 1D probe, however, the FE was more likely to perform accurately than the MFE, and thus, the FE was the optimum estimator. On the basis of these comparison results, we developed a recognizer for the optimum estimator. This developed recognizer provided a simple, reliable tool for selecting the optimum estimator to accurately produce a 3D orientation distribution estimation, which is beneficial to realistic fracture network modelling. Weakness of the developed recognizer was also disclosed.