{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T22:31:42Z","timestamp":1785537102689,"version":"3.56.0"},"reference-count":23,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2020,6,9]],"date-time":"2020-06-09T00:00:00Z","timestamp":1591660800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>This article provides an angular-based radiometric slope correction routine for Sentinel-1 SAR imagery on the Google Earth Engine platform. Two established physical reference models are implemented. The first model is optimised for vegetation applications by assuming volume scattering on the ground. The second model is optimised for surface scattering, and therefore targeted at urban environments or analysis of soil characteristics. The framework of both models is extended to simultaneously generate masks of invalid data in active layover and shadow affected areas. A case study, using openly available and reproducible code, exemplarily demonstrates the improvement of the backscatter signal in a mountainous area of the Austrian Alps. Furthermore, suggestions for specific use cases are discussed and drawbacks of the method with respect to pixel-area based methods are highlighted. The radiometrically corrected radar backscatter products are overcoming current limitations and are compliant with recent CEOS specifications for SAR backscatter over land. This improves a wide range of potential usage scenarios of the Google Earth Engine platform in mapping various land surface parameters with Sentinel-1 on a large scale and in a rapid manner. The provision of an openly accessible Earth Engine module allows users a smooth integration of the routine into their own workflows.<\/jats:p>","DOI":"10.3390\/rs12111867","type":"journal-article","created":{"date-parts":[[2020,6,9]],"date-time":"2020-06-09T06:34:16Z","timestamp":1591684456000},"page":"1867","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":166,"title":["Angular-Based Radiometric Slope Correction for Sentinel-1 on Google Earth Engine"],"prefix":"10.3390","volume":"12","author":[{"given":"Andreas","family":"Vollrath","sequence":"first","affiliation":[{"name":"European Space Agency, ESRIN, ESA Phi-Lab, Largo Galileo Galilei, 00044 Frascati (RM), Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7711-8523","authenticated-orcid":false,"given":"Adugna","family":"Mullissa","sequence":"additional","affiliation":[{"name":"Department of Environmental Sciences, Wageningen University and Research, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4327-4349","authenticated-orcid":false,"given":"Johannes","family":"Reiche","sequence":"additional","affiliation":[{"name":"Department of Environmental Sciences, Wageningen University and Research, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.rse.2017.06.031","article-title":"Google Earth Engine: Planetary-scale geospatial analysis for everyone","volume":"202","author":"Gorelick","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1038\/nclimate2919","article-title":"Combining satellite data for better tropical forest monitoring","volume":"6","author":"Reiche","year":"2016","journal-title":"Nat. Clim. Chang."},{"key":"ref_3","unstructured":"Google Developers (2020, March 17). Sentinel-1 Algorithms. Available online: https:\/\/developers.google.com\/earth-engine\/sentinel1."},{"key":"ref_4","unstructured":"Committee on Earth Observation Satellites (2020, March 17). Analysis Ready Data For Land. Available online: http:\/\/ceos.org\/ard\/files\/PFS\/v4.1\/CARD4L_Product_Family_Specification-Normalised_Radar_Backscatter-v4.1.pdf."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3081","DOI":"10.1109\/TGRS.2011.2120616","article-title":"Flattening gamma: Radiometric terrain correction for SAR imagery","volume":"49","author":"Small","year":"2011","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.rse.2014.08.037","article-title":"Multi-model radiometric slope correction of SAR images of complex terrain using a two-stage semi-empiralc approach","volume":"156","author":"Hoekman","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1109\/JSTARS.2010.2072984","article-title":"Ortho-Rectification and Slope Correction of SAR Data Using DEM and Its Accuracy Evaluation","volume":"3","author":"Shimada","year":"2010","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1109\/LGRS.2012.2192093","article-title":"DEM-based SAR pixel-area estimation for enhanced geocoding refinement and radiometric normalization","volume":"10","author":"Frey","year":"2013","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.enggeo.2006.09.013","article-title":"Investigating landslides with space-borne Synthetic Aperture Radar (SAR) interferometry","volume":"88","author":"Colesanti","year":"2006","journal-title":"Eng. Geol."},{"key":"ref_10","first-page":"2335","article-title":"Geocoding for classification of ERS\/JERS-1 SAR composites","volume":"4","author":"Kellndorfer","year":"1996","journal-title":"Int. Geosci. Remote Sens. Symp."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1109\/36.45752","article-title":"The Generation of SAR Layover and Shadow Maps from Digital Elevation Models","volume":"28","author":"Kropatsch","year":"1990","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_12","unstructured":"European Space Agency (2020, March 17). Sentinel-1 Toolbox. Available online: https:\/\/sentinel.esa.int\/web\/sentinel\/toolboxes\/sentinel-1."},{"key":"ref_13","unstructured":"Hoekman, D.H. (1990). Radar Remote Sensing Data for Applications in Forestry. [Ph.D. Thesis, Technical University Delft]."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.rse.2011.05.028","article-title":"GMES Sentinel-1 mission","volume":"120","author":"Torres","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_15","unstructured":"Greifeneder, F., and Google Earth Engine Developer Group (2020, May 15). Discussion on Derivation of Local Incidence Angle from Sentinel-1. Available online: https:\/\/groups.google.com\/forum\/#\\protect\\kern-.1667em\\relaxmsg\/google-earth-engine-developers\/3-q0TEwa-Tk\/h3J4havuBAAJ."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1115","DOI":"10.1109\/36.536527","article-title":"Radiometrie slope correction of synthetic-aperture radar images","volume":"34","author":"Ulander","year":"1996","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Chen, X., Sun, Q., and Hu, J. (2018). Generation of complete SAR geometric distortion maps based on DEM and neighbor gradient algorithm. Appl. Sci., 10.","DOI":"10.3390\/app8112206"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2005RG000183","article-title":"The Shuttle Radar Topography Mission","volume":"45","author":"Farr","year":"2007","journal-title":"Rev. Geophys."},{"key":"ref_19","unstructured":"GeoVille Information Systems Gmbh (2020, March 17). Land Information System Austria. Available online: https:\/\/www.landinformationsystem.at\/."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Reiche, J., Verhoeven, R., Verbesselt, J., Hamunyela, E., Wielaard, N., and Herold, M. (2018). Characterizing tropical forest cover loss using dense Sentinel-1 data and active fire alerts. Remote Sens., 10.","DOI":"10.3390\/rs10050777"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1016\/j.rse.2017.10.034","article-title":"Improving near-real time deforestation monitoring in tropical dry forests by combining dense Sentinel-1 time series with Landsat and ALOS-2 PALSAR-2","volume":"204","author":"Reiche","year":"2018","journal-title":"Remote Sens. Environ."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"605","DOI":"10.1109\/JSTARS.2010.2070059","article-title":"PALSAR Wide-Area Mapping of Borneo: Methodology and Map Validation","volume":"3","author":"Hoekman","year":"2010","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_23","unstructured":"Google Developers (2020, March 17). Datasets Tagged Elevation in Earth Engine. Available online: https:\/\/developers.google.com\/earth-engine\/datasets\/tags\/elevation."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/11\/1867\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:36:58Z","timestamp":1760175418000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/11\/1867"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,6,9]]},"references-count":23,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2020,6]]}},"alternative-id":["rs12111867"],"URL":"https:\/\/doi.org\/10.3390\/rs12111867","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,6,9]]}}}