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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-1097</article-id>
<title-group>
<article-title>Towards robust fracture mapping: benchmarking automatic fracture mapping in 2D outcrop imagery</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Fatihi</surname>
<given-names>Ayoub</given-names>
<ext-link>https://orcid.org/0000-0001-8572-6553</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Caldeira</surname>
<given-names>Jefter</given-names>
<ext-link>https://orcid.org/0009-0006-0145-2852</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Beucler</surname>
<given-names>Tom</given-names>
<ext-link>https://orcid.org/0000-0002-5731-1040</ext-link>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Thiele</surname>
<given-names>Samuel T.</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Samsu</surname>
<given-names>Anindita</given-names>
<ext-link>https://orcid.org/0000-0003-3588-2237</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Institute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, Switzerland</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Expertise Center for Climate Extremes, University of Lausanne, 1015 Lausanne, Switzerland</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Helmholtz Institute Freiberg, Helmholtz-Zentrum Dresden-Rossendorf, Chemnitzer Str. 40, 09599 Freiberg, Germany</addr-line>
</aff>
<pub-date pub-type="epub">
<day>13</day>
<month>03</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>35</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Ayoub Fatihi et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1097/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1097/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1097/egusphere-2026-1097.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1097/egusphere-2026-1097.pdf</self-uri>
<abstract>
<p>Extracting consistent and accurate fracture traces from large volumes of high-resolution imagery remains a persistent challenge in structural analysis. We present a harmonised benchmarking dataset, FraXet, for pixel-wise fracture segmentation in high-resolution RGB orthophotos and digital elevation models (DEMs). FraXet curates images from three publicly available datasets, totalling 8953 256&lt;span&gt;&amp;thinsp;&lt;/span&gt;&amp;times;&lt;span&gt;&amp;thinsp;&lt;/span&gt;256 RGB+DEM patches spanning diverse lithologies and imaging conditions. We use this dataset to systematically assess traditional image-processing filters (Canny, Sobel, Gabor, Sato, phase congruency) and two deep-learning (DL) models, U-Net and SegFormer, for per-pixel fracture detection. Quantitative comparison using image-quality (e.g., MSE, PSNR), segmentation (e.g., Precision, Recall, F1, IoU) and proposed similarity FracSim metrics suggest that the deep models substantially outperform classical filters (F1 &amp;asymp; 03 &lt;span&gt;&amp;minus;&lt;/span&gt;0.5 vs &amp;le; 0.29), giving smoother, more continuous fracture traces with reduced noise. Training on the combined dataset (M_all) improves cross-site generalisation relative to models trained on the individual sub-datasets. Challenges remain in handling annotation misalignments, illumination artifacts, and thin traces. More importantly, probability maps derived from the DL approaches enable confidence-based triage and visualisation of model uncertainty. This work thus establishes a unified benchmark, curated dataset, and reproducible baseline to support further development of robust automated tools for fracture detection.</p>
</abstract>
<counts><page-count count="35"/></counts>
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