{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:01:49Z","timestamp":1760148109555,"version":"build-2065373602"},"reference-count":29,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T00:00:00Z","timestamp":1680220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Australian Government\u2019s CRC Program"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Polarimetric Synthetic Aperture Radar Interferometry (Pol-InSAR) based forest height estimation for ecosystem monitoring and management has been developing rapidly in recent years. Spaceborne Pol-InSAR systems with long temporal baselines of several days always lead to severe temporal decorrelation, which can cause a forest height overestimation error. However, most forest height estimation studies have not considered the change in dielectric property as a factor that may cause temporal decorrelation with a long temporal baseline. Therefore, it is necessary to propose a new method that considers dielectric fluctuations and random motions of scattering elements to compensate for the temporal decorrelation effect. The lack of ground truth for forest canopy also needs a solution. Unsupervised methods could be a solution because they do not require the use of true values of tree heights as the ground truth to calculate their estimation accuracies. This paper aims to present an unsupervised forest height estimation method called Dielectric Fluctuation and Random Motion over Ground (DF-RMoG) to improve accuracy by considering the dielectric fluctuations and random motions. Its performance is investigated using Advanced Land Observing Satellite (ALOS)-1 Pol-InSAR data acquired over a German forest site with temporal intervals of 46 and 92 days. The authors analyze the relationship between forest height and different parameters with DF-RMoG and conventional models. Compared with conventional models, the proposed DF-RMoG model significantly reduces the overestimation error due to temporal decorrelation in forest height estimation according to its lowest average forest height.<\/jats:p>","DOI":"10.3390\/rs15071877","type":"journal-article","created":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T09:12:59Z","timestamp":1680253979000},"page":"1877","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dielectric Fluctuation and Random Motion over Ground Model (DF-RMoG): An Unsupervised Three-Stage Method of Forest Height Estimation Considering Dielectric Property Changes"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5672-9138","authenticated-orcid":false,"given":"Chang","family":"Liu","sequence":"first","affiliation":[{"name":"School of Civil and Environmental Engineering, Faculty of Engineering, University of New South Wales, Sydney, NSW 2052, Australia"}]},{"given":"Qi","family":"Zhang","sequence":"additional","affiliation":[{"name":"Data Science in Earth Observation, Technical University of Munich (TUM), 85521 Ottobrunn, Germany"}]},{"given":"Linlin","family":"Ge","sequence":"additional","affiliation":[{"name":"School of Civil and Environmental Engineering, Faculty of Engineering, University of New South Wales, Sydney, NSW 2052, Australia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2568-3111","authenticated-orcid":false,"given":"Samad M. E.","family":"Sepasgozar","sequence":"additional","affiliation":[{"name":"School of Built Environment, Faculty of Arts, Design & Architecture, University of New South Wales, Sydney, NSW 2052, Australia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8532-8440","authenticated-orcid":false,"given":"Ziheng","family":"Sheng","sequence":"additional","affiliation":[{"name":"School of Civil and Environmental Engineering, Faculty of Engineering, University of New South Wales, Sydney, NSW 2052, Australia"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Zhang, Q., Ge, L., and Du, Z. (August, January 28). A Modified RMoG Model for Forest Height Inversion Using L-Band Repeat-Pass Pol-InSAR Data. Proceedings of the IGARSS 2019\u20142019 IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan.","DOI":"10.1109\/IGARSS.2019.8900551"},{"key":"ref_2","first-page":"1814","article-title":"Radar polarimetry and polarimetric interferometry","volume":"84","author":"Cloude","year":"2001","journal-title":"IEICE Trans. Electron."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Papathanassiou, K., Reigber, A., Scheiber, R., Horn, R., Moreira, A., and Cloude, S. (1998, January 6\u201310). Airborne polarimetric SAR interferometry. Proceedings of the IGARSS 1998\u20141998 IEEE International Geoscience and Remote Sensing Symposium, Seattle, WA, USA.","DOI":"10.1109\/IGARSS.1998.703689"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.isprsjprs.2022.02.008","article-title":"PolGAN: A deep-learning-based unsupervised forest height estimation based on the synergy of PolInSAR and LiDAR data","volume":"186","author":"Zhang","year":"2022","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Xie, J., Li, L., Zhuang, L., and Zheng, Y. (2022). A New Strategy for Forest Height Estimation Using Airborne X-Band PolInSAR Data. Remote Sens., 14.","DOI":"10.3390\/rs14194743"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2352","DOI":"10.1109\/36.964971","article-title":"Single-baseline polarimetric SAR interferometry","volume":"39","author":"Papathanassiou","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Managhebi, T., Maghsoudi, Y., and Amani, M. (2022). Forest Height Retrieval Based on the Dual PolInSAR Images. Remote Sens., 14.","DOI":"10.3390\/rs14184503"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Eriksson, L.E., Santoro, M., and Fransson, J.E. (2008, January 6\u201311). Temporal decorrelation for forested areas observed in spaceborne L-band SAR interferometry. Proceedings of the IGARSS 2008\u2014IEEE 2008 Geoscience and Remote Sensing Symposium, Boston, MA, USA.","DOI":"10.1109\/IGARSS.2008.4780083"},{"key":"ref_9","unstructured":"Lee, S., Kugler, F., Papathanassiou, K., and Moreira, A. (2009, January 28). Forest height estimation by means of Pol-InSAR limitations posed by temporal decorrelation. Proceedings of the 11th ALOS Kyoto & Carbon Initiative, Tsukuba, Japan."},{"key":"ref_10","unstructured":"Papathanassiou, K., and Cloude, S.R. (2003, January 21\u201325). The effect of temporal decorrelation on the inversion of forest parameters from PoI-InSAR data. Proceedings of the IGARSS 2003\u2014IEEE 2003 International Geoscience and Remote Sensing Symposium, Toulouse, France."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2880","DOI":"10.1109\/TGRS.2011.2174367","article-title":"A temporal decorrelation model for polarimetric radar interferometers","volume":"50","author":"Lavalle","year":"2012","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1109\/JSTARS.2017.2761338","article-title":"An Assessment of Temporal Decorrelation Compensation Methods for Forest Canopy Height Estimation Using Airborne L-Band Same-Day Repeat-Pass Polarimetric SAR Interferometry","volume":"11","author":"Simard","year":"2018","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_13","unstructured":"Rosen, P.A., Hensley, S., Wheeler, K., Sadowy, G., Miller, T., Shaffer, S., Muellerschoen, R., Jones, C., Zebker, H., and Madsen, S. (2006, January 24\u201327). UAVSAR: A new NASA airborne SAR system for science and technology research. Proceedings of the 2006 IEEE International Radar Symposium, Verona, NY, USA."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"126990","DOI":"10.1016\/j.jhydrol.2021.126990","article-title":"Analysis of the impact of the South-to-North water diversion project on water balance and land subsidence in Beijing, China between 2007 and 2020","volume":"603","author":"Du","year":"2021","journal-title":"J. Hydrol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1080\/17455030.2016.1209594","article-title":"A physical scattering model of repeat-pass InSAR correlation for vegetation","volume":"27","author":"Lei","year":"2017","journal-title":"Waves Random Complex Media"},{"key":"ref_16","unstructured":"(2023, March 16). United States Geological Survey. USGS EROS Archive\u2014Digital Elevation\u2014Shuttle Radar Topography Mission (SRTM) 1 Arc-Second Global, Available online: https:\/\/www.usgs.gov\/centers\/eros\/science\/usgs-eros-archive-digital-elevation-shuttle-radar-topography-mission-srtm-1?qt-science_center_objects=0#qt-science_center_objects."},{"key":"ref_17","unstructured":"(2023, January 01). Federal Ministry of Food and Agriculture German. Spruce, Pine, Beech, Oak\u2014The Most Common Tree Species. Available online: https:\/\/www.bundeswaldinventur.de\/en\/third-national-forest-inventory\/the-forest-habitat-more-biological-diversity-in-the-forests\/spruce-pine-beech-oak-the-most-common-tree-species."},{"key":"ref_18","first-page":"102483","article-title":"An improved dual-baseline PolInSAR method for forest height inversion","volume":"103","author":"Shi","year":"2021","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_19","unstructured":"Ulaby, F.T., Moore, R.K., and Fung, A.K. (1982). Microwave Remote Sensing: Active and Passive: Volume 2\u2014Radar Remote Sensing and Surface Scattering and Emission Theory, Addison-Wesley."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Cloude, S. (2010). Polarisation: Applications in Remote Sensing, Oxford University Press.","DOI":"10.1093\/acprof:oso\/9780199569731.001.0001"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"498","DOI":"10.1109\/36.485127","article-title":"A review of target decomposition theorems in radar polarimetry","volume":"34","author":"Cloude","year":"1996","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2058","DOI":"10.1109\/TGRS.2005.853934","article-title":"Statistical assessment of eigenvector-based target decomposition theorems in radar polarimetry","volume":"43","author":"Pottier","year":"2005","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4752","DOI":"10.1109\/TGRS.2015.2409066","article-title":"Extraction of structural and dynamic properties of forests from polarimetric-interferometric SAR data affected by temporal decorrelation","volume":"53","author":"Lavalle","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2254","DOI":"10.1109\/TGRS.2003.817196","article-title":"Speckle filtering and coherence estimation of polarimetric SAR interferometry data for forest applications","volume":"41","author":"Lee","year":"2003","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1163\/156939300X00716","article-title":"Effect of medium symmetries on parameter estimation with polarimetric interferometry","volume":"14","author":"Moghaddam","year":"2000","journal-title":"J. Electromagn. Waves Appl."},{"key":"ref_26","unstructured":"Lee, S., Kugler, F., Hajnsek, I., and Papathanassiou, K.P. (2009, January 26\u201330). The impact of temporal decorrelation over forest terrain in polarimetric SAR interferometry. Proceedings of the 2nd International Workshop POLinSAR 2009, Frascati, Italy."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Lee, S.-K., Kugler, F., Papathanassiou, K., and Hajnsek, I. (2012, January 22\u201327). Quantification and compensation of temporal decorrelation effects in polarimetric SAR interferometry. Proceedings of the IGARSS 2012\u2014IEEE 2012 Geoscience and Remote Sensing Symposium, Munich, Germany.","DOI":"10.1109\/IGARSS.2012.6350768"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1109\/JSTARS.2013.2253448","article-title":"Quantification of temporal decorrelation effects at L-band for polarimetric SAR interferometry applications","volume":"6","author":"Lee","year":"2013","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_29","unstructured":"Lee, S.-K., Kugler, F., Papathanassiou, K.P., and Hajnsek, I. (2008, January 2\u20135). Quantifying temporal decorrelation over boreal forest at L-and P-band. Proceedings of the EUSAR 2008, Friedrichshafen, Germany."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/7\/1877\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:07:41Z","timestamp":1760123261000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/7\/1877"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,3,31]]},"references-count":29,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["rs15071877"],"URL":"https:\/\/doi.org\/10.3390\/rs15071877","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2023,3,31]]}}}