Geometric correction method for spotlight-mode satellite SAR (synthetic aperture radar) image

A geometric correction and space-borne technology, applied in the field of image processing, can solve problems such as equation parameter mismatch, large positioning error, and processing accuracy impact, and achieve the effect of improving processing efficiency, increasing processing speed, and reducing calculation amount

Inactive Publication Date: 2012-07-11
BEIHANG UNIV
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Problems solved by technology

Although this method improves the processing efficiency, the processing accuracy is greatly affected, and it is difficult to achieve high-precision geometric correction of spaceborne SAR images
[0008] However, both the geometric correction forward calculation method based on the range-Doppler (R-D) positioning model and the geometric correction inverse calculation method based on the simplified spaceborne SAR spatial geometric model are proposed for the sp

Method used

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  • Geometric correction method for spotlight-mode satellite SAR (synthetic aperture radar) image
  • Geometric correction method for spotlight-mode satellite SAR (synthetic aperture radar) image
  • Geometric correction method for spotlight-mode satellite SAR (synthetic aperture radar) image

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Embodiment

[0130] Embodiment: Taking a SAR image with a size of 4096×4096 as an example, the specific process is as follows figure 1 shown, including the following steps:

[0131] Step 1: Read in the relevant parameters and echo data, and establish a positioning equation consisting of three equations: slant distance equation, Doppler equation, and earth model equation on the basis of the geometric relationship between the satellite and the earth. The specific steps are divided into:

[0132] A. Read in geometric correction parameters, including ephemeris parameters and Doppler parameters: eccentricity e, semi-major axis a, ascending node equator Ω, perigee argument ω, orbital inclination i, periapsis time τ, deviation Navigation angle Ψ, pitch angle θ, roll angle Φ, radar irradiation center time t 0 , wavelength λ, Doppler center frequency Doppler frequency Reference slope distance R min , oblique angle φ, signal sampling rate f s , pulse repetition frequency prf, the approximate...

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Abstract

The invention discloses a geometric correction method for a spotlight-mode satellite SAR image. The method comprises the following steps: (1) reading related parameters and echo data, and constructing a positioning equation; (2) calculating the coordinates of the position vector and velocity vector of a satellite in a non-rotating geocentric coordinate system at a moment of radar illumination center according to the spatial geometric relationship between the satellite and the earth; (3) completing slope distance and Doppler frequency correction; (4) acquiring the coordinates as well as longitude and latitude of a certain pixel point (i, j) of the satellite SAR image in the non-rotating coordinate system; (5) determining whether all of the pixel points of the satellite SAR image are processed; and (6) re-dividing the latitude-longitude grid, and outputting the geometric correction result. The method provided by the invention can be used for carrying out row-by-row geometric correction on the satellite SAR image, and can process the satellite SAR image in blocks as required due to the completely independent treatment process between the rows of the satellite SAR image, thereby further improving the treatment efficiency.

Description

technical field [0001] The invention belongs to the field of image processing, and relates to an image geometric correction method, in particular to a high-precision geometric correction method of a spaceborne SAR image in a spotlight mode. Background technique [0002] Synthetic Aperture Radar (SAR) satellites have developed rapidly in recent years. Since SAR satellites are not limited by factors such as weather, geography, and time, they can observe the earth all day long and have certain penetrating power, so they are widely used. It is used in military reconnaissance, topographic mapping, resource detection, ocean observation, ecological monitoring, natural disaster monitoring, rapid rescue, etc. [0003] With the development of spaceborne SAR, the quality requirements for spaceborne SAR images are getting higher and higher, which not only requires radar images to have high spatial resolution, but also requires radar images to have high geometric fidelity and radiometric...

Claims

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Application Information

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IPC IPC(8): G01S13/90G01S7/40
Inventor 王鹏波门志荣陈杰杨威李春升刘月珊
Owner BEIHANG UNIV
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