Synthetic aperture radar interferometry: a model for the joint statistics in layover areas

The joint statistics of coregistered SAR images are studied, concentrating particularly on the statistics of the signals in layover areas of the SAR image. A new model for the joint statistics in layover areas (i.e., where several parts of the scene map into the same range bin) is derived. It is shown that, under certain assumptions, the statistics in layover areas may be modelled by a jointly circular Gaussian probability distribution, parameterized by the so-called covariance matrix. It is shown that the coherence between two SAR images may be expressed as the weighted average of the complex coherence values of each of the individual regions whose mappings are overlaid. The model is verified with simulated data.