3D Digital Geological Models

From Terrestrial Outcrops to Planetary Surfaces

Andrea Bistacchi, Matteo Massironi, Sophie Viseur, Andrea Bistacchi, Matteo Massironi, Sophie Viseur

• Publisher: Wiley
• Year: 2022
• Print ISBN:
  9781119313885
• eBook ISBN:
  9781119313892
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Geophysics

Discover the practical aspects of modeling techniques and their applicability on both terrestrial and extraterrestrial structures

A wide overlap exists in the methodologies used by geoscientists working on the Earth and those focused on other planetary bodies in the Solar System. Over the course of a series of sessions at the General Assemblies of the European Geosciences Union in Vienna, the intersection found in 3D characterization and modeling of geological and geomorphological structures for all terrestrial bodies in our solar system revealed that there are similar datasets and common techniques for the study of all planets—Earth and beyond—from a geological point-of-view. By looking at Digital Outcrop Models (DOMs), Digital Elevation Models (DEMs), or Shape Models (SM), the researcher may achieve digital representations of outcrops, topographic surfaces, or entire small bodies of the Solar System, like asteroids or comet nuclei.

3D Digital Geological Models has two central objectives, namely, to highlight the similarities that geological disciplines have in common when applied to entities in the Solar System, and to encourage interdisciplinary communication and collaboration between different scientific communities. The book particularly focuses on analytical techniques on DOMs, DEMs and SM that allow for quantitative characterization of outcrops and geomorphological features. It also highlights innovative 3D interpretation and modeling strategies that allow scientists to gain new and more advanced quantitative results on terrestrial and extraterrestrial structures.

3D Digital Geological Models readers will also find:

• The first volume dedicated to this subject matter that successfully integrates methodology and applications
• A series of methodological chapters that provide instruction on best practices involving DOMs, DEMs, and SMs
• A wide range of case studies, including small- to large-scale projects on Earth, Mars, the 67P/Churyumov-Gerasimenko comet, and the Moon
• Examples of how data collected at surface can help reconstruct 3D subsurface models

3D Digital Geological Models is a useful reference for academic researchers in earth science, structural geology, geophysics, petroleum geology, remote sensing, geostatistics, and planetary scientists, among others, and graduate students studying in these fields. It may also be of interest for professionals from industry, particularly those in the mining and hydrocarbon fields.

1
3D Digital Geological Models: From Terrestrial Outcrops to Planetary Surfaces

Andrea Bistacchi¹, Matteo Massironi², and Sophie Viseur³

¹Dipartimento di Scienze dell'Ambiente e della Terra, Università degli Studi di Milano - Bicocca, Piazza della Scienza, 4, 20126 Milano

²Dipartimento di Geoscienze, Università degli Studi di Padova, Via Gradenigo 6, 35131 Padova

³Aix Marseille Univ, CNRS, IRD, INRAE, Coll France, CEREGE., Case 67, 3 place Victor Hugo, 13331 Marseille CEDEX 03, France

Abstract

Collecting quantitative data to support geological analysis and modelling is nowadays a fundamental requirement in all geology disciplines, including structural geology, stratigraphy, and geomorphology, on the Earth and on planetary bodies of the Solar System. In many cases the answer to this need is a Digital Outcrop Model (DOM), a Digital Elevation Model (DEM), or a Shape Model (SM): this can be a digital representation of an outcrop or topographic surface, or of a whole small body (asteroid or comet nucleus) for an SM, generally combined with imagery, that can be quantitatively visualized and studied in 3D, with the goal of obtaining quantitative measurements.

3D datasets and models for geological purposes include different complementary products: DEMs, DOMs, SMs, and subsurface models. The main differences among these different products are: (i) their nature, since DEMs, DOMs, and SMs represent relief surfaces showing outcropping geological structures that are completely accessible to characterization (up to some precision/resolution), while subsurface models reproduce inaccessible subsurface geological structures with some unavoidable level of uncertainty (hence they are models); and (ii) their topology/dimensionality, as DEMs are actually 2.5D surfaces, generally covering large areas, DOMs are truly 3D surfaces, including multivalued reliefs (e.g. complex or overhanging reliefs, cliffs, caves, etc.), but are generally limited to smaller‐scale outcrops, and SMs are closed surfaces covering a whole small body, where subsurface models are essentially volumetric.

In this volume we collect various examples of methods and techniques used to collect, analyze, and model 3D datasets, based on one or more supports (DEM, DOM, SM, subsurface model), and on different software tools, remote sensing, and modelling techniques. Reading the chapters authored by experts in different fields, it will become apparent that (i) the fundamental techniques allowing the production of DEMs, DOMs, and SMs through photogrammetry, laser scanning devices, and radar interferometry are well consolidated, and are almost seamlessly shared between the community of scientists working on the Earth and on planetary bodies of the Solar System; (ii) the particular way these techniques are applied in specific geological environments may change and, for instance, acquisition schemes in photogrammetry still represent a potentially critical issue; (iii) DOM, DEM, and SM processing, elaboration and analysis, including the analysis of image data associated with these surfaces, are active fields of research that are subject to continuous improvements; and (iv) the production of subsurface geological models based (also) on surface data is still not very common, particularly in planetary geology contexts.

One of the aims of this volume is to disclose the numerous points that geological disciplines have in common in applications on the Earth and on planetary bodies of the Solar System, and to favor the communication and collaboration between different scientific communities.

1.1 Introduction

Collecting 3D quantitative data is a fundamental requirement in many structural geology, stratigraphy, sedimentology, geomorphology, and engineering geology projects both on the Earth and on planetary bodies of the Solar System (e.g. Bistacchi et al., 2011; Simioni et al., 2015; Jones et al., 2016; Tavani et al., 2016; Martinelli et al., 2017, 2020; Penasa et al., 2017; Triantafyllou et al., 2019; Siddiqui et al., 2019; Caravaca et al., 2020; Crane, 2020; De Toffoli et al., 2020; Le Mouélic et al., 2020). This can be achieved using different and complementary 3D datasets: Digital Elevation Models (DEMs), Digital Outcrop Models (DOMs), and Shape Models (SMs).

DEMs are 2.5D representations of topographic surfaces (e.g. Jones et al., 2008), generally with regional to global extension, produced through consolidated approaches from photogrammetry, laser scanning devices, and radar interferometry. DEMs are generally stored as 2D regular grids, but triangulated surfaces can be used in some applications, and are called Triangulated Irregular Networks (TINs) in GIS systems.

DOMs (e.g. Bellian et al., 2005) are instead digital high‐resolution representations of outcrops, or of the topographic surface at smaller scale. DOMs, represented as triangulated surfaces or point clouds, can represent multivalued reliefs (e.g. cliffs, caves, highly rough or overhanging reliefs) and can be really considered as 3D geometrical representations (Jones et al., 2008). DOMs can be textured if stored as triangulated surfaces (Catmull, 1974) and colored in case of point clouds (e.g. with RGB, LiDAR intensity). The textures mapped onto the surfaces may be single photos or, more recently, texture atlases (Lévy et al., 2002). DOMs can be visualized and studied, with dedicated software, with the final goal of obtaining quantitative measurements of sedimentary, stratigraphic, intrusive, tectonic, or geomorphological structures, or mapping lithology or alteration halos, etc.

SMs are produced for irregular small bodies of the Solar System, mainly using photogrammetric approaches (e.g. Carry et al., 2012; Preusker et al., 2012, 2015; Willner et al., 2014). Their particularity is that they are closed surfaces since they represent a whole small body. Apart from this, they share most other properties with DOMs.

3D geological models are 3D reconstructions of the subsurface geology and, historically, they have been produced based on geophysical and borehole/well datasets, mainly in oil and mining exploration contexts (e.g. Mallet, 2002, and references therein). More recently, they have been used also in other contexts, such as academic research projects or engineering geology, and, thanks to the emergence of high‐resolution DEMs and DOMs, they are also based on surface datasets. Subsurface geological models are often represented as a set of interface surfaces (e.g. faults, stratigraphic surfaces), termed as 3D Structural Models (Caumon et al., 2009), and sometimes as 3D structured or unstructured grids or meshes (Mallet, 2002) for specific applications (e.g. flow simulation, mechanical modelling, geostatistics). On planetary bodies of the Solar System, subsurface models have been reconstructed using surface data collected on DEMs, DOMs, or SMs (Penasa et al., 2017; Pozzobon et al., 2020; Franceschi et al., 2020), and also on subsurface geophysical datasets such as radargrams (Yuan et al., 2017).

Using the same techniques when reconstructing and analyzing DOMs, DEMs, SMs, and 3D subsurface geological models on the...

Table of contents

• Cover
• Table of Contents
• Title Page
• Copyright
• List of Contributors
• Preface
• 1 3D Digital Geological Models: From Terrestrial Outcrops to Planetary Surfaces
• Part I: DOM and SM Reconstruction and Interpretation Workflows
• Part II: Morphometric Analysis Across Different Scales and Planets
• Part III: 3D Modelling of the Subsurface from Surface Data
• Index
• End User License Agreement