Method of generating visual representation of terrain height from SAR data employing multigrid analysis
First Claim
1. A method of generating a digital elevation model of a surface comprising transmitting radar pulses from a synthetic aperture radar system to be reflected from said surface,receiving radar pulses reflected from said surface at a first angle and a second angle slightly different than said first angle with said synthetic aperture radar system,performing the following steps with a data processor:
- processing said received reflected radar pulses into a first set of data representing the phase of the received reflected pulses at said first angle from each increment of said surface and into a second set of data representing the phase of the reflected radar pulses at said second angle from each increment of said surface,determining a third set of data representing the difference in the phases between said first set of data and said second set of data for each of said increments, said third set of data representing the relative position of increments of said surface in modulo form, unwrapping said third set of data into a fourth set of digital data representing the relative position of said surface increments in digital form, said unwrapping step comprising determining partial derivatives of said third set of data and representing said partial derivatives as a fifth set of data,defining a least squares equation representing said fourth set of data in terms of said fifth set of data and the partial derivatives of said fourth set of data,solving said equation by relaxation in a multigrid algorithm which converges to said fourth set of data.
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Abstract
In a method of recovering data representing terrain height from a synthetic aperture radar system the phase data is unwrapped by a Gauss-Seidel relaxation technique applied to a least squares differential equation in a multigrid algorithm. In the multigrid algorithm the problem represented by the least squares equation is transferred to successively coarser grids to more quickly remove the low frequency components of error. The resulting interim solutions determined on the coarser grids are then transferred successively back to the finer grids to converge on the finest grid of the grid array.
43 Citations
13 Claims
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1. A method of generating a digital elevation model of a surface comprising transmitting radar pulses from a synthetic aperture radar system to be reflected from said surface,
receiving radar pulses reflected from said surface at a first angle and a second angle slightly different than said first angle with said synthetic aperture radar system, performing the following steps with a data processor: -
processing said received reflected radar pulses into a first set of data representing the phase of the received reflected pulses at said first angle from each increment of said surface and into a second set of data representing the phase of the reflected radar pulses at said second angle from each increment of said surface, determining a third set of data representing the difference in the phases between said first set of data and said second set of data for each of said increments, said third set of data representing the relative position of increments of said surface in modulo form, unwrapping said third set of data into a fourth set of digital data representing the relative position of said surface increments in digital form, said unwrapping step comprising determining partial derivatives of said third set of data and representing said partial derivatives as a fifth set of data, defining a least squares equation representing said fourth set of data in terms of said fifth set of data and the partial derivatives of said fourth set of data, solving said equation by relaxation in a multigrid algorithm which converges to said fourth set of data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification