{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,27]],"date-time":"2026-06-27T15:47:54Z","timestamp":1782575274194,"version":"3.54.5"},"reference-count":23,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2022,10,16]],"date-time":"2022-10-16T00:00:00Z","timestamp":1665878400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42127804"],"award-info":[{"award-number":["42127804"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In recent years, non-contact human\u2013computer interactions have aroused much attention. In this paper, we mainly propose a dual view observation system based on the frontal and side millimeter-wave radars (MWR) to collect echo data of the Air writing digits \u201c0~9\u201d, simultaneously. Additionally, we also propose a novel distance approximation method to make the trajectory reconstruction more efficient. To exploit these characteristics of spatial-temporal adjacency in handwriting digits, we propose a novel clustering algorithm, named the constrained density-based spatial clustering of application with noise (CDBSCAN), to remove background noise or clutter. Moreover, we also design a robust gesture segmentation method by using twice-difference and high\u2013low thresholds. In our trials and comparisons, based on the trajectories formulated by echo data series of time\u2013distance and time\u2013velocity of dual views, we present a lightweight-based convolution neural network (CNN) to realize these digits recognition. Experiment results show that our system has a relatively high recognition accuracy, which would provide a feasible application for future human\u2013computer interaction scenarios.<\/jats:p>","DOI":"10.3390\/rs14205177","type":"journal-article","created":{"date-parts":[[2022,10,17]],"date-time":"2022-10-17T03:43:58Z","timestamp":1665978238000},"page":"5177","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["New Application: A Hand Air Writing System Based on Radar Dual View Sequential Feature Fusion Idea"],"prefix":"10.3390","volume":"14","author":[{"given":"Yinan","family":"Zhao","sequence":"first","affiliation":[{"name":"School of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tao","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Harbin Institute of Technology, Weihai 264209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiang","family":"Feng","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Harbin Institute of Technology, Weihai 264209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhanfeng","family":"Zhao","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Harbin Institute of Technology, Weihai 264209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenqing","family":"Cui","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Harbin Institute of Technology, Weihai 264209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Fan","sequence":"additional","affiliation":[{"name":"School of Information Science and Engineering, Harbin Institute of Technology, Weihai 264209, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,16]]},"reference":[{"key":"ref_1","first-page":"5103112","article-title":"Semisupervised human activity recognition with radar micro-Doppler signatures","volume":"60","author":"Li","year":"2021","journal-title":"IEEE Trans. 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