In this paper we compare, using ISRO's RISAT-1 FRS-1 mode Compact Polarimetric (CL-Pol) data, two widely used hybrid polarimetric decomposition techniques, m-δ and m-χ decompositions, with regard to classification accuracy for various agricultural crops of north and west India. We show that the classification based on the m-χ decomposition results in better crop separability in general. But the crop stage and existence of orientating structures in the crops affects the efficacy of decomposition; a fact vividly brought out in this paper. Theoretical insights into the effectiveness of these decomposition techniques for different crop geometry are brought forth. We also compare the classification accuracy subsequent to polarimetric speckle filtering vis-a-vis spatial multilooking (downsampling). We show that usage of an appropriate polarimetric filter tends to produce comparable accuracy for most of the agricultural classes, as that of multilook case, without degrading spatial resolution. This work showcases a custom implementation of Stokes parameter based decomposition as well as POLSAR filter based on refined Lee algorithm, written in C and tailored to RISAT-1.
1. Raney, R. K., "Hybrid-polarimetry SAR architecture," IEEE Trans. Geosci. Remote Sens., Vol. 45, No. 11, 3397-3404, Nov. 2007. doi:10.1109/TGRS.2007.895883
2. Raney, R. K., "Dual-polarized SAR and stokes parameters," IEEE Geosci. Remote Sens. Lett., Vol. 3, No. 3, 317-319, Jul. 2006. doi:10.1109/LGRS.2006.871746
3. Charbonneau, F., "Compact polarimetry: General results," Proceedings of the 2nd Compact Polarimetry Workshop, Ottawa, Ont, January 6-7, 2009.
4. Charbonneau, F. J., B. Brisco, R. K. Raney, H. McNaim, C. Liu, P. W. Vachon, J. Shang, R. De Abreau, C. Champagne, A. Merzouki, and T. Geldsetzer, "Compact polarimetry overview and applications assessment," Can. J. Remote Sensing, Vol. 36, S298-S315, 2010. doi:10.5589/m10-062
5. Dubois-Fernandez, P., J.-C. Souyris, S. Angelliaume, and F. Garestier, "The compact polarimetry alternative for spaceborne SAR at low frequency," IEEE Trans. Geosci. Remote Sens., Vol. 46, 3208-3222, 2008. doi:10.1109/TGRS.2008.919143
6. Ainsworth, T. L., J. P Kelly, and J.-S. Lee, "Classification comparisons between dual-pol, compact polarimetry, and quad-pol imagery," ISPRS Journal of Photogrammetry and Remote Sensing, Vol. 64, No. 5, 464-471, 2009. doi:10.1016/j.isprsjprs.2008.12.008
7. Lee, J. S., "Digital image enhancement and noise filtering by use of local statistics," IEEE Transactions on Pattern Analysis and Machine Intelliegence, Vol. 2, No. 2, 165-168, 1980. doi:10.1109/TPAMI.1980.4766994
8. Lee, J. S., "Refined filtering of image noise using local statistics," Computer Vision, Graphics, and Image Processing, Vol. 15, 380-389, 1981. doi:10.1016/S0146-664X(81)80018-4
9. Lee, J. S., M. R. Grunes, and G. De Grandi, "Polarimetric SAR speckle filtering and its implication for classification," IEEE Transactions of Geoscience and Remote Sensing, Vol. 37, No. 5, 2363-2373, 1999. doi:10.1109/36.789635
10. Lee, J. S. and E. Pottier, Polarimetric Radar Imaging: From Basics to Applications, CRC Press, 2009. doi:10.1201/9781420054989
11. Stratton, J. A., Electromagnetic Theory, McGraw-Hill, New York, 1941.
12. Raney, R. K., "Decomposition of hybrid-polarity SAR data," PolIn-SAR 2007: Proceedings of the 3rd International Workshop on Science and Applications, Frascati, Italy, January 22-26, 2007, H. Lacoste and L. Ouwehand (eds.), ESA Publications, ESTEC, SP-644, Noordwijk, The Netherlands, 2007.
13. Jayasri, P. V., H. S. V. Usha Sundari, E. V. S. Sita Kumari, and A. V. V. Prasad, "M-delta decomposition of hybrid dual-polarimetric RISAT-1 SAR data," 9th International Radar Symposium India, 2013.
14. Lardeux, C., D. Niamen, J. B. Routier, A. Giraud, P. L. Frison, E. Pottier, and J. P. Rudant, "Assessment of compact polarimetry over different tropical environment and dataset," Geoscience and Remote Sensing Symposium (IGARSS), 3279-3282, 2010.
15. Lardeux, C., P.-L. Frison, C. Tison, J.-C. Souyris, B. Stoll, B. Fruneau, and J.-P. Rudant, "Support vector machine for multifrequency SAR polarimetric data classification," IEEE Trans. GRS, Vol. 47, No. 12, 4143-4152, 2009.
16. Tapan, M., S. S. Rana, N. M. Desai, D. B. Dave, Rajeevjyoti, R. K. Arora, C. V. N. Rao, B. V. Bakori, R. Neelakantan, and J. G. Vachchani, "Synthetic Aperture Radar payload on-board RISAT-1: configuration, technology and performance," Current Science, Vol. 104, No. 4, 2013.
17. Haldar, D., A. Das, S. Mohan, O. Pal, R. S. Hooda, and M. Chakraborty, "Assessment of L-band SAR data at different polarization combinations for crop and other landuse classification," Progress In Electromagnetics Research B, Vol. 36, 303-321, 2012. doi:10.2528/PIERB11071106
18. Haldar, D., M. Chakraborty, K. R. Manjunath, and J. S. Parihar, "Role of polarimetric SAR data for discrimination/biophysical parameters of crops based on canopy architecture," Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci. XL-8, ISPRS Technical Commission VIII Symposium, 737-744, Hyderabad, India, 2014. doi:10.5194/isprsarchives-XL-8-737-2014
19. Congalton, R. G., "A review of assessing the accuracy of classifications of remotely sensed data," Remote Sens. Environ., Vol. 37, 35-46, 1991. doi:10.1016/0034-4257(91)90048-B
20. Kumar, V. and Y. S. Rao, "Comparative analysis of RISAT-1 and simulated RADARSAT-2 hybrid polarimetric SAR data for different land features," Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci. XL-8, ISPRS Technical Commission VIII Symposium, Hyderabad, India, 2014.