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Clear-Cut Detection in Swedish Boreal Forest Using Multi-Temporal ALOS PALSAR Backscatter Data

M. Santoro ; J.E.S. Fransson ; Leif E.B. Eriksson (Institutionen för radio- och rymdvetenskap, Radarfjärranalys) ; Lars M. H. Ulander (Institutionen för radio- och rymdvetenskap, Radarfjärranalys)
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (1939-1404). Vol. 3 (2010), 4, p. 618-631.
[Artikel, refereegranskad vetenskaplig]

An extensive dataset of images acquired by the Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) is investigated for clear-cut detection in the county of Västerbotten, Sweden. Strong forest/non-forest contrast and temporal consistency were found for the Fine Beam Dual HV-polarized backscatter in summer/fall. In consequence of a clear-cut between image acquisitions, the HV-backscatter dropped in most cases between 2 and 3 dB. Thus, a simple thresholding algorithm that exploits the temporal consistency of time series of HV-backscatter measurements has been developed for clear-cut detection. The detection algorithm was applied at pixel level to ALOS PALSAR strip images with a pixel size of 50 m. The performance of the detection algorithm was tested with three different threshold values (2.0, 2.5 and 3.0 dB). The classification accuracy increased from 57.4% to 78.2% for decreasing value of the threshold. Conversely, the classification error increased from 3.0% to 9.7%. For about 90% of the clear-felled polygons used for accuracy assessment the proportion of pixels correctly detected as clear-felled was above 50% when using a threshold value of 2.0 dB. For the threshold values of 2.5 and 3.0 dB the corresponding figures were 80% and 65%, respectively. The total area classified as clear-felled during the time frame of the ALOS PALSAR data differed by 5% compared to an estimate of notified fellings for the same period of time when using a detection threshold of 2.5 dB. The performance of the simple detection algorithm is reasonable when aiming at detecting clear-cuts, whereas there are shortcomings in terms of delineation.

Nyckelord: ALOS, PALSAR, boreal forest, clear-cut, Kyoto & Carbon Initiative, SAR backscatter, Sweden



Denna post skapades 2010-12-29. Senast ändrad 2017-08-17.
CPL Pubid: 132108

 

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Institutioner (Chalmers)

Institutionen för radio- och rymdvetenskap, Radarfjärranalys (2005-2010)

Ämnesområden

Hållbar utveckling
Rymd- och flygteknik
Fjärranalys

Chalmers infrastruktur