1. A method of processing seismic data acquired at a plurality of locations, the method comprising: interpolating and/or extrapolating the seismic data-to estimate seismic data at a target location different from the plurality of locations, wherein the interpolating and/or extrapolating of the seismic data is performed in a polar co-ordinate system, and wherein a coordinate origin of the polar co-ordinate system is configured to be substantially coincident with a location of a seismic source used in the acquisition of the seismic data; and processing the estimated seismic data for the target location to obtain information about one or more parameters of the earth's interior.