Robust classification of SAR imagery

In this work the G/sub A//sup 0/ distribution is assumed as the universal model for amplitude synthetic aperture radar (SAR) imagery data under the multiplicative model. The observed data, therefore, is assumed to obey a G/sub A//sup 0/ (/spl alpha/, /spl gamma/, n) law, where the parameter n is related to the speckle noise, and (/spl alpha/, /spl gamma/) are related to the ground truth, giving information about the background. Therefore, maps generated by the estimation of (/spl alpha/, /spl gamma/) in each coordinate can be used as the input for classification methods. Maximum likelihood estimators are derived and used to form estimated parameter maps. This estimation can be hampered by the presence of corner reflectors, man-made objects used to calibrate SAR images that produce large return values. In order to alleviate this contamination, robust (M) estimators are also derived for the universal model. Gaussian maximum likelihood classification is used to obtain maps using hard-to-deal-with simulated data, and the superiority of robust estimation is quantitatively assessed.