{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:56:04Z","timestamp":1760241364975,"version":"build-2065373602"},"reference-count":42,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,2,4]],"date-time":"2018-02-04T00:00:00Z","timestamp":1517702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJGI"],"abstract":"<jats:p>Soil spectroscopy is a promising technique for soil analysis, and has been successfully utilized in the laboratory. When it comes to space, the presence of vegetation significantly affects the performance of imaging spectroscopy or hyperspectral imaging on the retrieval of topsoil properties. The Forced Invariance Approach has been proven able to effectively suppress the vegetation contribution to the mixed image pixel. It takes advantage of scene statistics and requires no specific a priori knowledge of the referenced spectra. However, the approach is still mainly limited to lithological mapping. In this case study, the objective was to test the performance of the Forced Invariance Approach to improve the estimation accuracy of soil salinity for an agricultural area located in the semi-arid region of Northwest China using airborne hyperspectral data. The ground truth data was obtained from an eco-hydrological wireless sensing network. The relationship between Normalized Difference Vegetation Index (NDVI) and soil salinity is discussed. The results demonstrate that the Forced Invariance Approach is able to improve the retrieval accuracy of soil salinity at a depth of 10 cm, as indicated by a higher value for the coefficient of determination (R2). Consequently, the vegetation suppression method has the potential to improve quantitative estimation of soil properties with multivariate statistical methods.<\/jats:p>","DOI":"10.3390\/ijgi7020048","type":"journal-article","created":{"date-parts":[[2018,2,5]],"date-time":"2018-02-05T04:29:42Z","timestamp":1517804982000},"page":"48","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["A Case Study of the Forced Invariance Approach for Soil Salinity Estimation in Vegetation-Covered Terrain Using Airborne Hyperspectral Imagery"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2001-7542","authenticated-orcid":false,"given":"Lanfa","family":"Liu","sequence":"first","affiliation":[{"name":"Institute for Cartography, TU Dresden, 01062 Dresden, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Min","family":"Ji","sequence":"additional","affiliation":[{"name":"Institute for Cartography, TU Dresden, 01062 Dresden, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6051-2249","authenticated-orcid":false,"given":"Manfred","family":"Buchroithner","sequence":"additional","affiliation":[{"name":"Institute for Cartography, TU Dresden, 01062 Dresden, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,2,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.geoderma.2005.10.009","article-title":"Detecting salinity hazards within a semiarid context by means of combining soil and remote-sensing data","volume":"134","author":"Douaoui","year":"2006","journal-title":"Geoderma"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1373","DOI":"10.1007\/s12517-014-1279-0","article-title":"Evaluation of soil salinization in a Mediterranean site (Agoulinitsa district-West Greece)","volume":"8","author":"Alexakis","year":"2014","journal-title":"Arabian J. 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