1. A method of computing wavenumber-frequency spectra comprising: computing in a sonar array processor, a position vector for each sensor in a three-dimensional array of sensors, each position vector representative of a coordinate position of a corresponding sensor on a geometric surface defined by the three-dimensional array of sensors, in three orthogonal directions; computing in the sonar array processor, a time Fourier transform on data from each said sensor in the array of sensors; computing, in the sonar array processor, a spatial Fourier transform based in part on each computed position vector; and outputting by the sonar array processor, results of said spatial Fourier transform, which is indicative of three-dimensional signal data received by said three-dimensional array of sensors, wherein each position vector is computed according to: r -> l , m = ρ ⁢ ⁢ cos ( 2 ⁢ π ⁢ ⁢ m M ) ⁢ x -> + ρ ⁢ ⁢ sin ( 2 ⁢ π ⁢ ⁢ m M ) ⁢ y -> + h ( l - 1 L - 1 - 0.5 ) ⁢ z -> where {right arrow over (x)}, {right arrow over (y)}, {right arrow over (z)} are unit vectors in the x,y,z coordinates; l,m are sensor position labeled corresponding to a layer l, and a circular position m; M is a number of elements per layer; L is a number of layers; h is the array height; and ρ is the radius of the array.