Analysis of L-band SAR backscatter and coherence for delineation of land-use/land-cover

Abstract

In this study, we investigated the potential improvement of land-use/land-cover (LU/LC) classification using multidate backscatter intensity as well as interferometric coherence images derived from Advanced Land Observing Satellite phased array L-band synthetic aperture radar data. Four interferometric synthetic aperture radar data pairs in horizontal–horizontal polarizations were processed to obtain backscatter intensity and coherence images. From the analysis of these images, it was observed that backscatter values alone are not sufficient to separate certain LU/LC classes, e.g. forest and mining areas, due to similarities in the associated scattering mechanisms producing similar backscatter values. However, the temporal coherence values from these LU/LC features were found to be distinctly different. Supervised classifications using maximum-likelihood distance were performed with various combinations of data (three-date backscatter intensity and two-date backscatter intensity with corresponding coherence data) to generate LU/LC maps of the study area. The comparison of classification accuracies obtained for different combinations of data indicates that the classification accuracy is improved by adding coherence information to the backscatter intensity data compared to using the multidate backscatter intensity data alone. Thus, the analysis of backscatter intensity along with coherence is a better alternative than using backscatter intensity alone to improve the accuracy in LU/LC classification.

Acknowledgements

The authors are thankful to JAXA, Japan, for providing ALOS-PALSAR and ALOS-AVNIR-2 data for this study. The authors from the Space Applications Centre (SAC) are thankful to the director, SAC, for supporting and providing facilities to carry out the present work. The work was carried out under the ALOS Announcement of Opportunities project funded by SAC (ISRO). We sincerely thank the anonymous referees and the editor for their critical reviews and comments.