{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T22:08:00Z","timestamp":1771366080962,"version":"3.50.1"},"reference-count":89,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2019,8,12]],"date-time":"2019-08-12T00:00:00Z","timestamp":1565568000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Across the world, cultural heritage is eradicated at an unprecedented rate by development, agriculture, and natural erosion. Remote sensing using airborne and satellite sensors is an essential tool for rapidly investigating human traces over large surfaces of our planet, but even large monumental structures may be visible as only faint indications on the surface. In this paper, we demonstrate the utility of a machine learning approach using airborne laser scanning data to address a \u201cneedle-in-a-haystack\u201d problem, which involves the search for remnants of Viking ring fortresses throughout Denmark. First ring detection was applied using the Hough circle transformations and template matching, which detected 202,048 circular features in Denmark. This was reduced to 199 candidate sites by using their geometric properties and the application of machine learning techniques to classify the cultural and topographic context of the features. Two of these near perfectly circular features are convincing candidates for Viking Age fortresses, and two are candidates for either glacial landscape features or simple meteor craters. Ground-truthing revealed the latter sites as ice age features, while the cultural heritage sites Borg\u00f8 and Tr\u00e6lbanke urge renewed archaeological investigation in the light of our findings. The fact that machine learning identifies compelling new candidate sites for ring fortresses demonstrates the power of the approach. Our automatic approach is applicable worldwide where digital terrain models are available to search for cultural heritage sites, geomorphological features, and meteor impact craters.<\/jats:p>","DOI":"10.3390\/rs11161881","type":"journal-article","created":{"date-parts":[[2019,8,12]],"date-time":"2019-08-12T06:38:02Z","timestamp":1565591882000},"page":"1881","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Searching for Viking Age Fortresses with Automatic Landscape Classification and Feature Detection"],"prefix":"10.3390","volume":"11","author":[{"given":"David","family":"Stott","sequence":"first","affiliation":[{"name":"Department of Archaeological Science and Conservation, Moesgaard Museum, Moesg\u00e5rd All\u00e9 20, 8270 H\u00f8jbjerg, Denmark"},{"name":"Department of Geoscience, Aarhus University, H\u00f8egh-Guldbergs Gade 2, 8000 Aarhus C, Denmark"}]},{"given":"S\u00f8ren Munch","family":"Kristiansen","sequence":"additional","affiliation":[{"name":"Department of Geoscience, Aarhus University, H\u00f8egh-Guldbergs Gade 2, 8000 Aarhus C, Denmark"},{"name":"Center for Urban Network Evolutions (UrbNet), Aarhus University, Moesg\u00e5rd All\u00e9 20, 8270 H\u00f8jbjerg, Denmark"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1254-1256","authenticated-orcid":false,"given":"S\u00f8ren Michael","family":"Sindb\u00e6k","sequence":"additional","affiliation":[{"name":"Center for Urban Network Evolutions (UrbNet), Aarhus University, Moesg\u00e5rd All\u00e9 20, 8270 H\u00f8jbjerg, Denmark"}]}],"member":"1968","published-online":{"date-parts":[[2019,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/j.jas.2014.08.010","article-title":"High resolution space and ground-based remote sensing and implications for landscape archaeology: The case from Portus, Italy","volume":"52","author":"Keay","year":"2014","journal-title":"J. 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