**5. Conclusions**

*4.2. Discussion* 

The above experimental results show that the proposed method can deal with the contour polylines obtained by geological logging in mine production with good effects. Firstly, the constructed model conforms to the geological trend and is smooth in every mesh. Secondly, the closed-loop division can be carried out automatically, which will greatly improve the efficiency of modeling. Thirdly, since modeling between different regions will not affect each other, it can be carried out at the same time, which will greatly reduce the overall modeling time. However, this method still has some limitations that need to be further studied and solved. Firstly, due to the inherent limitations of the Coons technology, the model constructed by Coons surface interpolation is difficult to update, and it is difficult to take faulting crosscutting into account, which will affect the accuracy We propose a modeling method based on bicubic Coons surface interpolation, which needs the contour polyline to be in an approximate plane within the tolerance range. The innovation of this paper is that we proposed a creative method of automatically dividing the closed loops, which will greatly reduce the modeling time. Additionally, the constructed sub-meshes can be combined without manual intervention. This method solves the problem that it is difficult to divide closed loops based on contour polylines with complex shapes, and it greatly improves the efficiency of modeling based on complex cross-contour polylines. Firstly, the contour polylines are cut by the approximate planes to divide the subspaces. Then, the divided polylines are grouped and connected according to the specified tolerance to form closed loops. Secondly, the Coons surface interpolation is used for modeling based on the closed-loop information. Finally, the constructed sub-meshes are combined to form a complete orebody model. Through experiments with multiple groups of cross-contour

of the model. In mine production, many orebodies are cross-cut by faults. For these orebodies, we should choose other modeling methods. Secondly, due to the complexity of

polylines, as shown in Figure 15, it can not complete all closed-loop divisions well, which needs to be specified manually. Finally, before Coons surface interpolation, all regions except simple single-sided regions need to be transformed into four-sided regions, which may affect the final modeling results by introducing numerical instability issues when adding virtual edges and vertexes. Therefore, to further improve the efficiency and accuracy of the modeling of cross-contour polylines, it is necessary to develop a closedpolylines, the results show that the proposed method can accurately divide closed loops and model the contour polylines with good effects.

**Author Contributions:** Conceptualization, Z.W., L.B., D.Z. and Q.T.; methodology, Z.W., L.B., D.Z., J.Z. and Q.T.; software, Z.W., L.B., D.Z., J.Z. and Q.T.; formal analysis, Z.W., L.B., and D.Z.; data curation, Z.W., and D.Z.; writing—original draft preparation, Z.W.; writing—review and editing, Z.W., L.B. and D.Z.; visualization, Z.W., L.B., D.Z., and J.Z.; project administration, L.B., and M.J.; funding acquisition, D.Z. and M.J. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (52104171), the National Key R&D Program of China (2019YFC0605304), and the China Postdoctoral Science Foundation (2022T150740).

**Acknowledgments:** We thank the reviewers for their comments and suggestions to improve the quality of the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
