6 Wavelet Analysis of SAR Images in the Marginal Ice Zone
127
In this work the wavelet transform was applied to satellite SAR imagery and the feasibility of this technique for feature extraction was demonstrated. Especially when the
signal-to-noise ratio is relatively low in the satellite imagery, this technique of extracting features first and then matching the features in sequential images is very efficient
and promising. This kind of SAR processing by wavelet transform as described here
can be used interactively as needed for operation and also applied to the mapping of
mesoscale ocean features in the coastal zone (Liang et al.1995; Liu et al.1997). The wavelet
transforms of satellite images can be used for near real-time "quick look" screening of
satellite data (feature detection), data reduction (binary image), and image enhancement (edge linking). By combining ocean color SeaWiFS/OCTS, ERS-2/RADARSAT
SAR, and infrared AVHRR images (wavelet transformed binary images) by a data
fusion technique, mesoscale features of various physical processes such as oil spills, surfate slicks, fronts, upwelling, eddies, ice floes, and ice edge meandering can be detected and tracked in the coastal area and in the MIZ. Reliable imaging of such mesoscale
features by certain sensors and definition of the conditions under which imaging is
possible will provide a better understanding of the processes.
Acknowledgments. The authors wish to thank Ron Kwok and Ben Holt of the Jet
Propulsion Laboratory and Seelye Martin of the University of Washington for their valuable discussions and suggestions. The ERS-1 SAR images were collected by ESA satellite and processed by ASP. This work was supported by the National Aeronautics and
Space Administration and the Office of Naval Research.
References
Ballard DH, Brown CM (1982) Computer vision. Prentice-Hall, Englewood Cliffs, New
Jersey
Canny J, (1986) A computational approach to edge detection. IEEE Trans Pattern Analysis and Machine Intelligence 8: 679-698
Combes JM, Grossmann A, Tchamitchian Ph (eds) (1989) Wavelet: time frequency
methods and phase space. Proc Int Wavelet Conf, December 14-18, 1987, Marseille,
France, Springer, Berlin Heidelberg New York
Kwok R, Rothrock DA, Cunningham GF, Stern H (1994) Determination of ice age: a proposed scheme for a RADARSAT sea ice geophysical processor system. Proc Int Geosci
Remote Sens Symp IGARSS' 94,August 8-12, Pasadena, California, pp 1750-1752
Liang NK, Liu AK, Peng CY (1995) A preliminary study of SAR imagery on Taiwan
coastal water. Acta Oceanogr Taiwanica 34: 17-28
Liu AK (1995) Study of waves in ice-covered ocean using SAR. In: Ikeda M, Dobson F
(eds) Oceanographic application of remote sensing. CRC Press, New York, pp 397-404
Liu AK, Peng CY (1992) Waves and mesoscale features in the marginal ice zone. Proc 1st
ERS-1 Symp, November 4-6, Cannes, France, pp 343-348
Liu AK, Peng CY (1993a) Synthetic aperture radar for ocean applications. Proc of Symp
Remote Sensing in Environmental Research and Global Change. Environment '93,
Hong Kong, pp 167-182
Liu AK, Peng CY (1993b) Ocean-ice interaction in the marginal ice zone. Proc 2nd ERS1 Symp, Hamburg, Germany, October 11-14, 1993. ESA SP-361 (January 1994): 317-322
127
In this work the wavelet transform was applied to satellite SAR imagery and the feasibility of this technique for feature extraction was demonstrated. Especially when the
signal-to-noise ratio is relatively low in the satellite imagery, this technique of extracting features first and then matching the features in sequential images is very efficient
and promising. This kind of SAR processing by wavelet transform as described here
can be used interactively as needed for operation and also applied to the mapping of
mesoscale ocean features in the coastal zone (Liang et al.1995; Liu et al.1997). The wavelet
transforms of satellite images can be used for near real-time "quick look" screening of
satellite data (feature detection), data reduction (binary image), and image enhancement (edge linking). By combining ocean color SeaWiFS/OCTS, ERS-2/RADARSAT
SAR, and infrared AVHRR images (wavelet transformed binary images) by a data
fusion technique, mesoscale features of various physical processes such as oil spills, surfate slicks, fronts, upwelling, eddies, ice floes, and ice edge meandering can be detected and tracked in the coastal area and in the MIZ. Reliable imaging of such mesoscale
features by certain sensors and definition of the conditions under which imaging is
possible will provide a better understanding of the processes.
Acknowledgments. The authors wish to thank Ron Kwok and Ben Holt of the Jet
Propulsion Laboratory and Seelye Martin of the University of Washington for their valuable discussions and suggestions. The ERS-1 SAR images were collected by ESA satellite and processed by ASP. This work was supported by the National Aeronautics and
Space Administration and the Office of Naval Research.
References
Ballard DH, Brown CM (1982) Computer vision. Prentice-Hall, Englewood Cliffs, New
Jersey
Canny J, (1986) A computational approach to edge detection. IEEE Trans Pattern Analysis and Machine Intelligence 8: 679-698
Combes JM, Grossmann A, Tchamitchian Ph (eds) (1989) Wavelet: time frequency
methods and phase space. Proc Int Wavelet Conf, December 14-18, 1987, Marseille,
France, Springer, Berlin Heidelberg New York
Kwok R, Rothrock DA, Cunningham GF, Stern H (1994) Determination of ice age: a proposed scheme for a RADARSAT sea ice geophysical processor system. Proc Int Geosci
Remote Sens Symp IGARSS' 94,August 8-12, Pasadena, California, pp 1750-1752
Liang NK, Liu AK, Peng CY (1995) A preliminary study of SAR imagery on Taiwan
coastal water. Acta Oceanogr Taiwanica 34: 17-28
Liu AK (1995) Study of waves in ice-covered ocean using SAR. In: Ikeda M, Dobson F
(eds) Oceanographic application of remote sensing. CRC Press, New York, pp 397-404
Liu AK, Peng CY (1992) Waves and mesoscale features in the marginal ice zone. Proc 1st
ERS-1 Symp, November 4-6, Cannes, France, pp 343-348
Liu AK, Peng CY (1993a) Synthetic aperture radar for ocean applications. Proc of Symp
Remote Sensing in Environmental Research and Global Change. Environment '93,
Hong Kong, pp 167-182
Liu AK, Peng CY (1993b) Ocean-ice interaction in the marginal ice zone. Proc 2nd ERS1 Symp, Hamburg, Germany, October 11-14, 1993. ESA SP-361 (January 1994): 317-322