Fransson, Johan
- Department of Forest Resource Management, Swedish University of Agricultural Sciences
Research article2010Peer reviewed
Clear-Cut Detection in Swedish Boreal Forest Using Multi-Temporal ALOS PALSAR Backscatter Data
Santoro, Maurizio; Fransson, Johan; Eriksson, Leif E.B.; Ulander, Lars M.H
Abstract
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 V sterbotten, Sweden. Strong forest/non-forest contrast and temporal consistency were found for the Fine Beam Dual H.V-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.
Keywords
ALOS PALSAR; boreal forest; clear-cut; Kyoto & Carbon Initiative; SAR backscatter; Sweden
Published in
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
2010, volume: 3, number: 4, pages: 618-631
Publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
SLU Authors
UKÄ Subject classification
Earth Observation
Forest Science
Physical Geography
Publication identifier
- DOI: https://doi.org/10.1109/JSTARS.2010.2048201
Permanent link to this page (URI)
https://res.slu.se/id/publ/60554