Modelling Orebody Structures: Block Merging Algorithms and Block Model Spatial Restructuring Strategies Given Mesh Surfaces of Geological Boundaries

Raymond Leung

doi:10.5311/josis.2020.21.582

Abstract

This paper describes a framework for capturing geological structures in a 3D block model and improving its spatial fidelity given new mesh surfaces. Using surfaces that represent geological boundaries, the objectives are to identify areas where refinement is needed, increase spatial resolution to minimize surface approximation error, reduce redundancy to increase the compactness of the model and identify the geological domain on a block-by-block basis. These objectives are fulfilled by four system components which perform block-surface overlap detection, spatial structure decomposition, sub-blocks consolidation and block tagging, respectively. The main contributions are a coordinate-ascent merging algorithm and a flexible architecture for updating the spatial structure of a block model when given multiple surfaces, which emphasizes the ability to selectively retain or modify previously assigned block labels. The techniques employed include block-surface intersection analysis based on the separable axis theorem and ray-tracing for establishing the location of blocks relative to surfaces. To demonstrate the robustness and applicability of the proposed block merging strategy in a more narrow setting, it is used to reduce block fragmentation in an existing model where surfaces are not given and the minimum block size is fixed. To obtain further insight, a systematic comparison with octree subblocking subsequently illustrates the inherent constraints of dyadic hierarchical decomposition and the importance of inter-scale merging. The results show the proposed method produces merged blocks with less extreme aspect ratios and is highly amenable to parallel processing. The overall framework is applicable to orebody modelling given geological boundaries, and 3D segmentation more generally, where there is a need to delineate spatial regions using mesh surfaces within a block model.

Highlights

JOSIS, as Mike Worboys put it in his editorial introducing the first issue ten years ago, is “an online publication and all articles are free to access for any person” [17]
We asked all members of our editorial board to write vision pieces showing the diversity of ways in which our field can contribute to both basic science and major societal challenges
Some editorial board members chose to write their piece alone; others asked colleagues to contribute. These are diverse, and they span a range of topics

Summary

Introduction

JOSIS, as Mike Worboys put it in his editorial introducing the first issue ten years ago, is “an online publication and all articles are free to access for any person” [17]. Climate change has become a climate emergency, biodiversity and nature’s contributions to people have been recognized as important contributors to Sustainable Development Goals1, easy access to locationenabled devices in many people’s pockets has changed the way that societies operate, and most recently, a global pandemic has impacted on all of our lives. All of these events bring into sharp focus the ways in which the data, technologies, and methods we work on can be used for good.

Results

Conclusion