In a first aspect, the present invention provides a method for performing radar image segmentation, the method comprising: using a radar, generating a radar image of an area of terrain, the radar image deriving from radar observations taken along a plurality of azimuth angles; performing a background extraction process on the radar image to extract a background image comprising extracted radar observations, the background extraction process comprising estimating a range spread of a radar echo from the surface of the terrain as function of the azimuth angle and a tilt of the radar relative to the surface of the terrain; fitting a model to the extracted radar observations along a particular azimuth angle; determining a value of a parameter indicative of the goodness of fit between the model and the extracted radar observations along the particular azimuth angle; and determining a classification depending on the value of the parameter for that azimuth angle.