Attitude Adjustment and Nonlinear Calibration Method for Imaging the Same Region of Inhomogeneous Scene

Abstract

The invention relates to an attitude adjustment and nonlinear calibration method for imaging in the identical region of a heterogeneous scene. The attitude adjustment and nonlinear calibration method comprises the following steps: calculating an initial drift angle of satellite imaging and adjusting a satellite yaw angle, transferring into a calibration mode of imaging in the same region of the heterogeneous scene; accurately calculating an image drift size by adopting a top-down time interface step length in an imaging process of the calibration mode, controlling an accurate push-sweeping direction of imaging of a linear array CCD (Charge Coupled Device) through adjusting the satellite yaw angle to ensure that the linear array CCD can be used for sequentially imaging the identical region; and determining whether the obtained image data meets the condition of nonlinear calibration, and if being met, establishing a nonlinear calibration mapping relationship table on the basis of histogram matching histogram matching, and if not, re-determining an imaging scene to continuously execute on-tract calibration so that more image data is obtained. The attitude adjustment and nonlinear calibration method is low in requirement for a ground scene without a more uniform scene; a non-uniform scene can meet a calibration task, each track of satellite operating can realize calibration, with high calibration frequency.

Description

technical field [0001] The invention relates to an attitude adjustment and non-linear calibration method for imaging the same area of ​​a non-uniform scene, belongs to the technical field of remote sensing satellite calibration, and is especially used for attitude adjustment and non-linear calibration of an optical remote sensing satellite linear array CCD camera for imaging the same area of ​​​​a non-uniform scene. Linear scaling. Background technique [0002] At present, the linear array CCD cameras of optical remote sensing satellites mainly use push-broom imaging to acquire satellite images. However, there are problems such as non-uniformity noise and dark current noise in each CCD detector and amplification gain of the remote sensing satellite camera, which leads to inconsistency in the response of the optical system and CCD detector, which is directly manifested in the inconsistency of the output gray value of each pixel , resulting in some "banding" or "streaks" in t...

AI Technical Summary

Problems solved by technology

① Laboratory calibration method before satellite launch. This method obtains calibration coefficients through the image data of multiple calibration lamps in the laboratory. However, after the satellite is launched to in-orbit operation, the devices carried will change to a certain extent.

② Use the on-board calibration device for on-orbit calibration. This method requires a standard on-board calibration source, but due to the low stability of the calibration source, the application efficiency of this calibration method is low

③Constructing a large-area uniform calibration field on the ground requires a lot of financial and material resources to maintain, affected by weather conditions, orbital movement, etc., the cycle of calibration is very long, and the goal is single, it is difficult to achieve multi-point nonlinearity Correction

④ Utilize the uniform ground scenery in nature such as lakes, grasslands, glaciers, etc., but there are few absolutely uniform scenery in such a large area, and it is also difficult to achieve high-precision nonlinear calibration

⑤ The on-orbit statistical method based on multi-track data is also a method that is widely used at present. This method needs to accumulate multi-track image data and establish a histogram lookup table based on histogram matching. However, this method must ensure the stability of each track data sex

⑥ The Side-slither calibration method proposed abroad for agile satellites (see Radiometric correction of Rapid Eye imagery using the on-orbitside-slither method, SPIE, 2011), rotates the yaw angle of the satellite by 90°, and needs to select relatively uniform scenes such as rain forests, deserts, and ice sheets as the calibration method. Therefore, the high requirements for the calibration source lead to the limited selection of the calibration area, which affects the calibration frequency

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