Patent ID: 8903134

Claim:
A method for determining depth and surface current in a body of water comprising obtaining a first plurality of overhead images of an area of said body of water wherein said first plurality of images has pixel intensity correlated with wave height; obtaining a second plurality of images by preprocessing said first plurality of images, as and if needed, such that all images of said second plurality of images are mapped onto a grid of fixed coordinates, and the pixel intensities have a near linear relationship to wave height; obtaining a two-dimensional Fourier transform of each of said second plurality of images; finding an extremum of an objective function, wherein said objective function is a function of ℑ 2 −1 [G(F 1 ,ΦF 2 )] where ℑ 2 −1 is the inverse two-dimensional Fourier transform operator, G is a mathematical function, F 1 is a first two-dimensional Fourier transform of a first image of said second plurality of images, ΦF 2 is a second two-dimensional Fourier transform of a second image of said second plurality of images, said second two-dimensional Fourier transform propagated to the time of said first image, Φ is a gravity wave propagation function, Φ being a function of the depth and surface current (velocity) vector at each pixel location in said second plurality of images; and wherein the depth and/or surface current vector at each pixel location are varied as independent fitting parameters to find said extremum, and wherein said extremum is sharply peaked at a particular set of depth values and a particular set of surface current vector values; and displaying said particular set of depth and/or surface current vector values as numbers, as maps, or by other suitable data visualization means.