{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T17:36:06Z","timestamp":1771608966579,"version":"3.50.1"},"reference-count":79,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2022,4,8]],"date-time":"2022-04-08T00:00:00Z","timestamp":1649376000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000844","name":"European Space Agency","doi-asserted-by":"publisher","award":["4000125506\/18\/NL\/IA"],"award-info":[{"award-number":["4000125506\/18\/NL\/IA"]}],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In the next few years, the new Copernicus Hyperspectral Imaging Mission (CHIME) is foreseen to be launched by the European Space Agency (ESA). This mission will provide an unprecedented amount of hyperspectral data, enabling new research possibilities within several fields of natural resources, including the \u201cagriculture and food security\u201d domain. In order to efficiently exploit this upcoming hyperspectral data stream, new processing methods and techniques need to be studied and implemented. In this work, the hybrid approach (HYB) and its variant, featuring sampling dimensionality reduction through active learning heuristics (HAL), were applied to CHIME-like data to evaluate the retrieval of crop traits, such as chlorophyll and nitrogen content at both leaf (LCC and LNC) and canopy level (CCC and CNC). The results showed that HYB was able to provide reliable estimations at canopy level (R2 = 0.79, RMSE = 0.38 g m\u22122 for CCC and R2 = 0.84, RMSE = 1.10 g m\u22122 for CNC) but failed at leaf level. The HAL approach improved retrieval accuracy at canopy level (best metric: R2 = 0.88 and RMSE = 0.21 g m\u22122 for CCC; R2 = 0.93 and RMSE = 0.71 g m\u22122 for CNC), providing good results also at leaf level (best metrics: R2 = 0.72 and RMSE = 3.31 \u03bcg cm\u22122 for LCC; R2 = 0.56 and RMSE = 0.02 mg cm\u22122 for LNC). The promising results obtained through the hybrid approach support the feasibility of an operational retrieval of chlorophyll and nitrogen content, e.g., in the framework of the future CHIME mission. However, further efforts are required to investigate the approach across different years, sites and crop types in order to improve its transferability to other contexts.<\/jats:p>","DOI":"10.3390\/rs14081792","type":"journal-article","created":{"date-parts":[[2022,4,9]],"date-time":"2022-04-09T05:13:08Z","timestamp":1649481188000},"page":"1792","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":51,"title":["Evaluation of Hybrid Models to Estimate Chlorophyll and Nitrogen Content of Maize Crops in the Framework of the Future CHIME Mission"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5270-071X","authenticated-orcid":false,"given":"Gabriele","family":"Candiani","sequence":"first","affiliation":[{"name":"Institute for Electromagnetic Sensing of the Environment, National Research Council, 20133 Milan, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9725-9956","authenticated-orcid":false,"given":"Giulia","family":"Tagliabue","sequence":"additional","affiliation":[{"name":"Remote Sensing of Environmental Dynamics Laboratory, University of Milano-Bicocca, 20126 Milan, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3745-8037","authenticated-orcid":false,"given":"Cinzia","family":"Panigada","sequence":"additional","affiliation":[{"name":"Remote Sensing of Environmental Dynamics Laboratory, University of Milano-Bicocca, 20126 Milan, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6313-2081","authenticated-orcid":false,"given":"Jochem","family":"Verrelst","sequence":"additional","affiliation":[{"name":"Image Processing Laboratory, University of Val\u00e8ncia, 46980 Val\u00e8ncia, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6803-9978","authenticated-orcid":false,"given":"Valentina","family":"Picchi","sequence":"additional","affiliation":[{"name":"Research Centre for Engineering and Agro-Food Processing, Council for Agricultural Research and Economics, 20133 Milan, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3188-1448","authenticated-orcid":false,"given":"Juan Pablo","family":"Rivera Caicedo","sequence":"additional","affiliation":[{"name":"Secretary of Research and Postgraduate, CONACYT-UAN, Tepic 63000, Nayarit, Mexico"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2156-4166","authenticated-orcid":false,"given":"Mirco","family":"Boschetti","sequence":"additional","affiliation":[{"name":"Institute for Electromagnetic Sensing of the Environment, National Research Council, 20133 Milan, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Loizzo, R., Daraio, M., Guarini, R., Longo, F., Lorusso, R., Dini, L., and Lopinto, E. 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