Terrain influences on SAR backscatter around Mt. Taranaki, New Zealand

An L-band SAR image from the Japanese JERS-1 satellite has been analyzed for the effects of local surface orientation relative to the radar illumination direction. Orthorectification of the SAR imagery and determination of the local surface orientation is achieved with the aid of a high resolution digital terrain model. An improved method of determining scatterer density for a surface in three dimensions is introduced and used to correct radiometrically the image for terrain variation. Residual radiometric effects due to surface orientation are shown to be dependent on the ground cover class. Backscatter from the indigenous forest was more isotropic than that from the farmland. As accurate registration was required for this study, a method for identifying control points in the rectified imagery is described which alleviated the difficulty of identifying them in the raw image.