{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,24]],"date-time":"2026-01-24T19:01:15Z","timestamp":1769281275776,"version":"3.49.0"},"reference-count":75,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,2]],"date-time":"2021-03-02T00:00:00Z","timestamp":1614643200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001665","name":"Agence Nationale de la Recherche","doi-asserted-by":"publisher","award":["ANR- 09-VILL-0007"],"award-info":[{"award-number":["ANR- 09-VILL-0007"]}],"id":[{"id":"10.13039\/501100001665","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>With the advancement of high spatial resolution imaging spectroscopy, an accurate surface reflectance retrieval is needed to derive relevant physical variables for land cover mapping, soil, and vegetation monitoring. One challenge is to deal with tree shadows using atmospheric correction models if the tree crown transmittance Tc is not properly taken into account. This requires knowledge of the complex radiation mechanisms that occur in tree crowns, which can be provided by coupling the physical modeling of canopy radiative transfer codes (here DART) and the 3D representations of trees. First in this study, a sensitivity analysis carried out on DART simulations with an empirical 3D tree model led to a statistical regression predicting Tc from the tree leaf area index (LAI) and the solar zenith angle with good performances (RMSE \u2264 4.3% and R2 \u2265 0.91 for LAI \u2264 4 m2.m\u22122). Secondly, more realistic 3D voxel-grid tree models derived from terrestrial LiDAR measurements over two trees were considered. The comparison of DART-simulated Tc from these models with the previous predicted Tc over 0.4\u20132.5 \u00b5m showed three main sources of inaccuracy quoted in order of importance: (1) the global tree geometry shape (mean bias up to 21.5%), (2) the transmittance fraction associated to multiple scattering, Tscat (maximum bias up to 13%), and (3) the degree of realism of the tree representation (mean bias up to 7.5%). Results showed that neglecting Tc leads to very inaccurate reflectance retrieval (mean bias &gt; 0.04), particularly if the background reflectance is high, and in the near and shortwave infrared \u2013 NIR and SWIR \u2013 due to Tscat. The transmittance fraction associated to the non-intercepted transmitted light, Tdir, can reach up to 95% in the SWIR, and Tscat up to 20% in the NIR. Their spatial contributions computed in the tree shadow have a maximum dispersion of 27% and 8% respectively. Investigating how to approximate Tdir and Tscat spectral and spatial variability along with the most appropriate tree 3D modeling is crucial to improve reflectance retrieval in tree shadows when using atmospheric correction models.<\/jats:p>","DOI":"10.3390\/rs13050931","type":"journal-article","created":{"date-parts":[[2021,3,2]],"date-time":"2021-03-02T21:24:01Z","timestamp":1614720241000},"page":"931","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Impact of Tree Crown Transmittance on Surface Reflectance Retrieval in the Shade for High Spatial Resolution Imaging Spectroscopy: A Simulation Analysis Based on Tree Modeling Scenarios"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6514-3561","authenticated-orcid":false,"given":"Karine R. M.","family":"Adeline","sequence":"first","affiliation":[{"name":"ONERA-DOTA, University of Toulouse, FR-31055 Toulouse, France"},{"name":"Universit\u00e9 F\u00e9d\u00e9rale Toulouse Midi-Pyr\u00e9n\u00e9es, 41 All\u00e9es Jules Guesde, 31013 Toulouse, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1229-7396","authenticated-orcid":false,"given":"Xavier","family":"Briottet","sequence":"additional","affiliation":[{"name":"ONERA-DOTA, University of Toulouse, FR-31055 Toulouse, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8332-972X","authenticated-orcid":false,"given":"Sidonie","family":"Lefebvre","sequence":"additional","affiliation":[{"name":"ONERA-DOTA, University of Paris Saclay, 91123 Palaiseau, France"}]},{"given":"Nicolas","family":"Rivi\u00e8re","sequence":"additional","affiliation":[{"name":"ONERA-DOTA, University of Toulouse, FR-31055 Toulouse, France"}]},{"given":"Jean-Philippe","family":"Gastellu-Etchegorry","sequence":"additional","affiliation":[{"name":"CESBIO, Toulouse III University, CNRS, CNES, IRD, INRA, 31401 Toulouse, France"}]},{"given":"Fabrice","family":"Vinatier","sequence":"additional","affiliation":[{"name":"LISAH, University of Montpellier, INRAE, IRD, Institut Agro, 34060 Montpellier, France"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1641\/0006-3568(2004)054[0523:UISTSE]2.0.CO;2","article-title":"Using imaging spectroscopy to study ecosystem processes and properties","volume":"54","author":"Ustin","year":"2004","journal-title":"Bioscience"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1007\/s10712-019-09524-0","article-title":"Imaging Spectroscopy for Soil Mapping and Monitoring","volume":"40","author":"Chabrillat","year":"2019","journal-title":"Surv. 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