Thierry Coowar’s scientific contributions

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Publications (2)


(a) Flowchart of the unsupervised clustering-based fold detection algorithm. (b) Example showing how a grid of rays is created across a geologic map from which data are to be extracted.
Synthetic geological model used to illustrate the unsupervised learning method. (a) The geological map in the absence of topography (at approximately the mean elevation of (b)), with the axes of the two anticlines marked by dotted lines. (b) The topography of the model (with elevations in meters above the base of the model). (c) The geologic map formed by the intersection of the topography with the geologic model, with the topographic contours from (b) overlaid. (d) A cross section illustrating the two anticlines and the syncline in the model. The color scale is the same in (a), (c), and (d).
Illustration of clustering-based unsupervised fold identification using the synthetic geological map from Fig. 2. The relative unit ages are now represented in grayscale in order to show the fold identification process more clearly. (a) One of the rays used to sample the map divided into segments corresponding to the geologic units of the map. (b) All ray segments along which possible folds were identified. (c) The midpoints of the possible fold segments. (d) The midpoints after rejection based on bedding orientation to exclude fold-mimicking topography. (e) The midpoints as clustered by HDBSCAN. (f) The points to be used for finding the fold axes, which exclude points from (e) for which rays cross at a high angle to the strike of the bedding. (g) The fold axes fit to the points in (f). (h) The line segments corresponding to the midpoints in (e). (i) The fold areas identified by finding the convex hulls of the line segments in (h).
Sparse categorical cross-entropy loss from training the convolutional neural network. (a) Training and validation losses with our preferred hyperparameters. (b–f) Training losses with various alternative values for hyperparameters: the learning rate, the batch size, the number of levels of the U-Net, the number of features at the first level of the U-Net, and the activation function. In (b)–(f), the second value (the orange line) is the value used in the preferred model in (a).
The fold identification process with the convolutional neural network, illustrated using the example from Figs. 2 and 3. (a, b) The input consists of two raster images, both scaled between 0 and 1, with the first giving the geological map in terms of the relative age of the units and the second giving the elevation. (c–e) The output consists of the probabilities that each pixel belongs to each of three classes: Class 1 for the background, Class 2 for off-axis parts of the fold, and Class 3 for the fold axis. The three class probabilities sum to 1 at each pixel. (f–h) The truth is plotted with each pixel given a probability of 1 for the correct class and 0 for the other classes.

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GEOMAPLEARN 1.2: detecting structures from geological maps with machine learning – the case of geological folds
  • Article
  • Full-text available

February 2025

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115 Reads

David Oakley

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Thierry Coowar

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[...]

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The increasing availability of large geological datasets and modern methods of data analysis facilitate a data science approach to geology in which inferences are drawn from geological data using automated methods based on statistics and machine learning. Such methods offer the potential for faster and less subjective interpretations of geological data than are possible from a human interpreter, but translating the understanding of a trained geologist to an algorithm is not straightforward. In this paper, we present automated workflows for detecting geological folds from map data using both unsupervised and supervised machine learning. For the unsupervised case, we use regular expression matching to identify map patterns suggestive of folds along lines crossing the map. We then use the HDBSCAN clustering algorithm to cluster these possible fold identifications into a smaller number of distinct folds. This clustering algorithm is chosen because it does not require the number of clusters to be known a priori. For the supervised learning case, we use synthetic models of folds to train a convolutional neural network to identify folds using map and topographic data. We test both methods on synthetic and real datasets, where they both prove capable of identifying folds. We also find that distinguishing folds from similar map patterns produced by topography is a major issue that must be accounted for with both methods. The unsupervised method has advantages, including the explainability of its results, and provides clearly better results in one of the two real-world test datasets, while the supervised learning method is more fully automated and likely more easily extensible to other structures. Both methods demonstrate the ability of machine learning to interpret folds on geological maps and have potential for further development targeting a wider range of structures and datasets.

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GEOMAPLEARN 1.0: Detecting geological structures from geological maps with machine learning

May 2024

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118 Reads

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1 Citation

The increasing availability of large geological datasets together with modern methods of data analysis facilitate a data science approach to geology in which inferences are drawn from geological data using automated methods based on statistics and machine learning. Such methods offer the potential for faster and less subjective interpretations of geological data than are possible from a human interpreter, but translating the understanding of a trained geologist to an algorithm is not straightforward. In this paper, we present automated workflows for detecting geological folds from map data using both unsupervised and supervised machine learning. For the unsupervised case, we use regular expression matching to identify map patterns suggestive of folds along lines crossing the map. We then use the hdbscan clustering algorithm to cluster these possible fold identifications into a smaller number of distinct folds, the number of which is not known a priori. For the supervised learning case, we use synthetic models of folds to train a convolutional neural network to identify folds using map and topographic data. We test both methods on synthetic and real datasets.

Citations (1)


... The observed deformation pattern could be interpreted by experts as one or more folding structures, or some faulted displaced blocks. The generation of such hypotheses is intuitive for human interpreters familiar with deformation concepts, but challenging for machines (Oakley et al. 2024). For sake of example, let the chosen hypothesis be the existence of some folds. ...

Reference:

A knowledge-driven modeling formalism for automatic structural interpretation
GEOMAPLEARN 1.0: Detecting geological structures from geological maps with machine learning