{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T11:29:43Z","timestamp":1786706983877,"version":"build-2736575974"},"reference-count":36,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T00:00:00Z","timestamp":1786665600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100014538","name":"Indonesia Endowment Fund for Education (LPDP), Ministry of Finance of the Republic of Indonesia","doi-asserted-by":"publisher","award":["LOG-13094\/LPDP.3\/2024"],"award-info":[{"award-number":["LOG-13094\/LPDP.3\/2024"]}],"id":[{"id":"10.13039\/501100014538","id-type":"DOI","asserted-by":"publisher"}]},{"award":["LOG-13094\/LPDP.3\/2024"],"award-info":[{"award-number":["LOG-13094\/LPDP.3\/2024"]}],"id":[{"id":"https:\/\/ror.org\/05p2xef58","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>(1) Background: Reliable forehead region-of-interest (ROI) localization remains challenging in low-resolution thermal imaging because limited spatial detail increases localization uncertainty. This study develops a lightweight nostril-anchored geometric ROI projection method for contactless forehead skin temperature estimation. (2) Methods: The forehead ROI was projected from the detected nostril bounding box using anthropometry-guided proportional geometry, followed by 95th-percentile (P95) spatial aggregation and exponential moving average (EMA) stabilization. Direct localization was evaluated against fixed-crop and MediaPipe Pose-based baselines using 120 annotated pilot frames across 0.5\u20131.5 m, followed by validation on 150 additional annotated frames from ten formal participants. A medical non-contact infrared forehead thermometer targeting the same central forehead region was used as a practical, rather than traceably calibrated, comparator. (3) Results: The proposed method outperformed the two localization baselines in the pilot evaluation. Formal-cohort validation achieved an overall IoU of 0.714, FIR of 0.870, and NCE of 0.091, with a 0.7% spatial-failure rate. Across 90 temperature measurements, the method achieved an MAE of 0.514\u00a0\u00b0C, RMSE of 0.614\u00a0\u00b0C, and mean bias of \u22120.187\u00a0\u00b0C, with 95% Bland\u2013Altman limits of agreement from \u22121.340\u00a0\u00b0C to 0.966\u00a0\u00b0C. Real-time implementation achieved 24.12\u00b11.43 FPS on a Jetson Orin Nano. (4) Conclusions: The proposed method provides a computationally efficient forehead ROI localization approach for low-resolution thermal imaging. Localization was strongest at 0.5 m and lower at farther distances; therefore, its scale adaptation should not be interpreted as distance-invariant performance. The temperature results represent agreement with the practical comparator rather than absolute clinical accuracy.<\/jats:p>","DOI":"10.3390\/s26165147","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T10:39:01Z","timestamp":1786703941000},"page":"5147","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Nostril-Anchored Geometric ROI Projection for Contactless Forehead Skin Temperature Estimation Using Low-Resolution Thermal Imaging"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9614-6386","authenticated-orcid":false,"given":"Riska","family":"Analia","sequence":"first","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"},{"name":"Department of Electrical Engineering, Politeknik Negeri Batam, Batam 29461, Indonesia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7466-4414","authenticated-orcid":false,"given":"Anne","family":"Forster","sequence":"additional","affiliation":[{"name":"Academic Unit for Ageing and Stroke Research, Leeds Institute of Health Sciences, University of Leeds, Leeds LS2 9LN, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2641-2620","authenticated-orcid":false,"given":"Sheng-Quan","family":"Xie","sequence":"additional","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0204-3867","authenticated-orcid":false,"given":"Zhiqiang","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"R33","DOI":"10.1088\/0967-3334\/33\/3\/R33","article-title":"Infrared thermal imaging in medicine","volume":"33","author":"Ring","year":"2012","journal-title":"Physiol. 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