Long linear array payload scanning imaging correction method and system for geostationary meteorological satellites

Abstract

The present invention provides a method and system for correcting the scanning imaging of a long linear array payload on a geostationary meteorological satellite. The method comprises the following steps: Step S1: Modeling the optical path based on the imaging principle of the long linear array scanning imaging payload to describe the error mechanism of the long linear array scanning imaging payload; Step S2: Derivation of a geometric correction model for the long linear array scanning imaging; and Step S3: Implementing pixel-by-pixel scanning imaging correction based on the geometric correction model. The imaging correction method proposed in the present invention can effectively compensate for the imaging errors of the long linear array payload.

Description

Technical Field

[0001] The present invention relates to the overall technology of spacecraft, and in particular to a method and system for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite. Background Art

[0002] With the continuous development of my country's high-orbit remote sensing satellites, high-orbit Earth remote sensing technology is evolving towards diversified detection methods, more refined detection targets, and more quantitative detection. New remote sensing payloads are emerging continuously. Long linear array payloads, with their advantages of large swath width, fast imaging speed, and stable scanning control, are important payloads for geostationary meteorological satellites. However, due to the large detector angle and strong coupling with the scanning mechanism, long linear array payloads can cause scanning imaging errors, seriously affecting the application of remote sensing images.

[0003] A literature search revealed that Wu Yinan, Zhang Yu, Han Shuangli, and others published a paper titled "Image Motion Matching and MTF Analysis of Long-Array TDICCD Space Cameras" (Electronic Measurement Technology, 2014). This paper mentions that long-array space cameras can achieve wider ground widths and shorten revisit cycles through maneuverable imaging. Due to factors such as angle shifts and the curvature of the Earth, the image motion velocity and drift angle at different camera field-of-view positions vary. The longer the focal plane of the long-array and the larger the maneuvering angle, the greater the difference. By calculating the image velocity vector at each point on the image plane using an image motion analytical model, the impact of differences in image motion velocity and drift angle at each point in the field of view of the space camera on the modulation transfer function during pan and tilt imaging is quantitatively analyzed. This article focuses on the impact of the long-array imaging environment on the modulation transfer function and proposes corresponding solutions, but does not address correction methods for long-array geometric imaging.

[0004] In their published paper, "A Geometric Correction Method for Infrared Swinging Imaging," published in Electronic Measurement Technology in 2018, Ding Yifan, You Hongjian, Chen Shuangjun, and others proposed a geometric correction method for infrared swinging imaging. This method uses single-frame images to construct a rigorous line-of-sight-based model and performs forward calculations. Multiple single-frame images are then projected onto a plane for stitching, and the resulting RPC model is constructed as a whole for inverse calculations. This method achieves high-precision geometric correction of infrared swinging imaging. The paper focuses on the geometric correction method for whole-satellite swinging payloads and does not address the geometric correction of long linear array scanning imaging. Summary of the Invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a method and system for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite.

[0006] A method for correcting long linear array payload scanning imaging of a geostationary meteorological satellite provided by the present invention comprises the following steps:

[0007] Step S1: Based on the imaging principle of the long linear array scanning imaging payload, optical path modeling is performed to describe the long linear array payload scanning imaging error mechanism;

[0008] Step S2: deriving a long linear array scanning imaging geometric correction model;

[0009] Step S3: Implement pixel-by-pixel scanning imaging correction based on the geometric correction model.

[0010] Preferably, in step S1, the optical path modeling adopts a line-of-sight reflection modeling method, starting from the long linear array pixel, and obtaining the load output light pointing model through detector angle change, east-west mirror reflection, and north-south mirror reflection.

[0011] Preferably, the scanning imaging geometric correction model in step S2 derives an equivalent compensation formula based on the theoretical scanning path of the long linear array load and the actual scanning path deviation.

[0012] Preferably, the scanning imaging geometric correction model in step S2 includes detector pixel numbers, east-west mirror scanning angles, and north-south mirror scanning angle model parameters.

[0013] Preferably, in step S3, the scanning imaging correction is performed pixel-by-pixel by pixel geometric correction based on an equivalent compensation amount, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path.

[0014] According to the present invention, a geostationary meteorological satellite long linear array payload scanning imaging correction system includes the following modules:

[0015] Module M1: Based on the imaging principle of the long linear array scanning imaging payload, optical path modeling is performed to describe the error mechanism of the long linear array payload scanning imaging.

[0016] Module M2: Derive the geometric correction model for long linear array scanning imaging;

[0017] Module M3: Implement pixel-by-pixel scanning imaging correction based on the geometric correction model.

[0018] Preferably, in the module M1, the optical path modeling adopts the line-of-sight reflection modeling method, starting from the long linear array pixel, and obtaining the load output light pointing model through the detector angle change, east-west mirror reflection and north-south mirror reflection.

[0019] Preferably, the scanning imaging geometric correction model in the module M2 derives an equivalent compensation formula based on the theoretical scanning path of the long linear array payload and the actual scanning path deviation.

[0020] Preferably, the scanning imaging geometric correction model in the module M2 includes detector pixel numbers, east-west mirror scanning angles, and north-south mirror scanning angle model parameters.

[0021] Preferably, in the module M3, the scanning imaging correction adopts a pixel-by-pixel geometric correction based on an equivalent compensation amount, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The imaging correction method proposed in the present invention can effectively compensate for the imaging error of long linear array payloads. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0025] Figure 1 This is a relative relationship diagram of the long linear array load light path reflection benchmark in an embodiment of the present invention;

[0026] Figure 2 This is a diagram showing the simulation results of long linear array load scanning imaging in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the long linear array load resampling principle in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the stellar target identification principle for space debris detection in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0030] The present invention provides a method for correcting long linear array payload scanning imaging of a geostationary meteorological satellite, comprising the following steps:

[0031] Step S1: Based on the imaging principle of the long linear array scanning imaging payload, optical path modeling is performed to describe the error mechanism of the long linear array payload scanning imaging. The optical path modeling adopts the line-of-sight reflection modeling method, starting from the long linear array pixel, and obtaining the payload output light pointing model through the detector angle change, east-west mirror reflection, and north-south mirror reflection.

[0032] In view of the geometric optical path reflection characteristics of the long linear array payload, the line-of-sight reflection modeling method is adopted. Starting from the long linear array pixel, the payload output light pointing model is obtained through the detector angle change, east-west mirror reflection, and north-south mirror reflection, thereby realizing pixel-by-pixel optical path modeling.

[0033] In the process of modeling the long linear array optical path, the detector pixel number, the east-west mirror scanning angle, and the north-south mirror scanning angle are used as model parameters. Combined with the relative geometric relationship of each reflective component, the direction of the payload's outgoing line of sight is deduced. Based on the reflection model, the satellite body coordinate system, the detector coordinate system, the east-west mirror rotation axis fixed coordinate system, and the north-south mirror rotation axis fixed coordinate system are established. The relative angle relationship of each coordinate system is shown in the attached figure. Figure 1 As shown. The transformation relationship from the light emitted by the detector to the light emitted by the light shield is:

[0034]

[0035] In the above formula, ε is the east-west mirror rotation angle, η is the north-south mirror rotation angle, a y is the angle between the long linear array pixel and the detector center.

[0036] N X is the east-west mirror reflection matrix, and its expression is:

[0037]

[0038] N z is the north-south mirror reflection matrix, and its expression is:

[0039]

[0040] C X (·) is the X-axis rotation function, and the function expression is:

[0041]

[0042] C Z (·) is the Z-direction rotation function, and the function expression is:

[0043]

[0044] Based on the above geometric model, the line of sight of the long linear array payload scanning imaging was calculated. The results are shown in the attached figure. Figure 2 According to the calculation results, the intersection area of ​​the two scanning lines of the long linear array produces misalignment and overlap, which causes imaging errors.

[0045] Step S2: Derive a long linear array scanning imaging geometric correction model. The scanning imaging geometric correction model derives an equivalent compensation formula based on the theoretical scanning path and actual scanning path deviation of the long linear array payload. The scanning imaging geometric correction model includes model parameters such as detector pixel number, east-west mirror scanning angle, and north-south mirror scanning angle.

[0046] The imaging errors corresponding to different areas of the long linear array payload optical axis are inconsistent. The imaging errors of different pixels in a single exposure of the long linear array are also inconsistent. In order to decouple the long linear array detector from the two-dimensional scanning mechanism, east-west correction and north-south correction are introduced into the line of sight model. Combined with model parameters such as the detector pixel number, the east-west mirror scanning angle, and the north-south mirror scanning angle, an equivalent compensation model is derived.

[0047] The compensation mechanism for long linear array scanning imaging errors is to increase the correction amount so that the actual line of sight vector of each pixel in the long linear array is consistent with the theoretical line of sight vector. The derived correction model is as follows:

[0048]

[0049] In the above formula, Δη is the north-south correction amount, and Δε is the east-west correction amount. By simplifying the above model formula, the geometric correction model can be derived:

[0050]

[0051] Δη=tan(a y )·η 2

[0052] In the above formula, ε is the east-west mirror rotation angle, η is the north-south mirror rotation angle, a y is the angle between the long linear array pixel and the detector center.

[0053] Step S3: Implement pixel-by-pixel scanning imaging correction based on the geometric correction model. The scanning imaging correction uses an equivalent compensation amount to implement pixel-by-pixel geometric correction, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path.

[0054] According to the above geometric correction model formula, the equivalent compensation method can be used to achieve pixel-by-pixel geometric correction, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path. In the image correction process, the pixel resampling method is used to obtain the corrected image. The resampling principle is as shown in the attached figure. Figure 3 The image comparison before and after correction is shown in the attached Figure 4 .

[0055] Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, and units provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same functions of the system and its various devices, modules, and units provided by the present invention in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; the devices, modules, and units for implementing various functions can also be considered as both software modules implementing the method and structures within the hardware component.

[0056] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite, characterized in that: The following steps are involved: Step S1: Based on the imaging principle of the long linear array scanning imaging payload, optical path modeling is performed to describe the long linear array payload scanning imaging error mechanism; Step S2: deriving a long linear array scanning imaging geometric correction model; Step S3: Implement pixel-by-pixel scanning imaging correction based on the geometric correction model; In step S1, the optical path modeling adopts the line-of-sight reflection modeling method, starting from the long linear array pixel, and obtaining the load outgoing light pointing model through the detector angle change, east-west mirror reflection, and north-south mirror reflection; In the process of modeling the long linear array optical path, the detector pixel number, the east-west mirror scanning angle, and the north-south mirror scanning angle are used as model parameters. Combined with the relative geometric relationship of each reflective component, the direction of the payload's output line of sight is derived. Based on the reflection model, the satellite body coordinate system, the detector coordinate system, the east-west mirror rotation axis fixed coordinate system, and the north-south mirror rotation axis fixed coordinate system are established. The transformation relationship from the detector output light to the light output light of the light shield is: In the above formula, ε is the east-west mirror rotation angle, η is the north-south mirror rotation angle, a y is the angle between the long linear array pixel and the detector center; N X is the east-west mirror reflection matrix, and its expression is: N z is the north-south mirror reflection matrix, and its expression is: C X (·) is the X-axis rotation function, and the function expression is: C Z (·) is the Z-direction rotation function, and the function expression is: Based on the above geometric model, the line of sight of the long linear array payload scanning imaging is calculated. According to the calculation results, the intersection area of ​​the two scanning lines of the long linear array produces misalignment and overlap, causing imaging errors.

2. The method for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite according to claim 1, characterized in that: The scanning imaging geometric correction model in step S2 derives an equivalent compensation formula based on the theoretical scanning path of the long linear array load and the actual scanning path deviation.

3. The method for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite according to claim 1, characterized in that: The scanning imaging geometric correction model in step S2 includes detector pixel numbers, east-west mirror scanning angles, and north-south mirror scanning angle model parameters.

4. The method for correcting the long linear array payload scanning imaging of a geostationary meteorological satellite according to claim 1, characterized in that: In step S3, the scanning imaging correction is performed pixel-by-pixel by pixel-based geometric correction in a manner based on an equivalent compensation amount, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path.

5. A long linear array payload scanning imaging correction system for a geostationary meteorological satellite, characterized in that: Includes the following modules: Module M1: Based on the imaging principle of the long linear array scanning imaging payload, optical path modeling is performed to describe the error mechanism of the long linear array payload scanning imaging. Module M2: Derive the geometric correction model for long linear array scanning imaging; Module M3: Pixel-by-pixel scanning imaging correction based on the geometric correction model; In the module M1, the optical path modeling adopts the line-of-sight reflection modeling method, starting from the long linear array pixel, and obtaining the load outgoing light pointing model through the detector angle change, east-west mirror reflection, and north-south mirror reflection; In the process of modeling the long linear array optical path, the detector pixel number, the east-west mirror scanning angle, and the north-south mirror scanning angle are used as model parameters. Combined with the relative geometric relationship of each reflective component, the direction of the payload's output line of sight is derived. Based on the reflection model, the satellite body coordinate system, the detector coordinate system, the east-west mirror rotation axis fixed coordinate system, and the north-south mirror rotation axis fixed coordinate system are established. The transformation relationship from the detector output light to the light output light of the light shield is: In the above formula, ε is the east-west mirror rotation angle, η is the north-south mirror rotation angle, a y is the angle between the long linear array pixel and the detector center; N X is the east-west mirror reflection matrix, and its expression is: N z is the north-south mirror reflection matrix, and its expression is: C X (·) is the X-axis rotation function, and the function expression is: C Z (·) is the Z-direction rotation function, and the function expression is: Based on the above geometric model, the line of sight of the long linear array payload scanning imaging is calculated. According to the calculation results, the intersection area of ​​the two scanning lines of the long linear array produces misalignment and overlap, causing imaging errors.

6. The geostationary meteorological satellite long linear array payload scanning imaging correction system according to claim 5, characterized in that: The scanning imaging geometric correction model in the module M2 derives an equivalent compensation formula based on the theoretical scanning path of the long linear array payload and the actual scanning path deviation.

7. The long linear array payload scanning imaging correction system for a geostationary meteorological satellite according to claim 5, characterized in that: The scanning imaging geometric correction model in the module M2 includes the detector pixel number, the east-west mirror scanning angle, and the north-south mirror scanning angle model parameters.

8. The long linear array payload scanning imaging correction system for a geostationary meteorological satellite according to claim 5, characterized in that: In the module M3, the scanning imaging correction is implemented pixel-by-pixel geometric correction based on an equivalent compensation amount, so that the corrected long linear array load scanning path is consistent with the theoretical scanning path.

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