Autonomous solar glare suppression method and system for high-orbit optical remote sensing satellites

Abstract

The present invention discloses a method and system for autonomously suppressing solar glare by a high-orbit optical remote sensing satellite. The method pre-calculates the glare area and accurately selects the necessity and feasibility of the autonomous glare suppression task. Then, the satellite attitude maneuverability is used to rotate the angle to achieve polarization imaging, effectively suppressing solar glare. At the same time, the imaging efficiency loss caused by traditional methods such as avoidance and elimination is avoided, and the problem that high-orbit optical remote sensing satellites cannot obtain high-fidelity remote sensing images in the glare area is solved. The method is suitable for high-orbit optical remote sensing satellites designed with polarizers and having agile maneuverability.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-interference of optical remote sensing satellites, and in particular to a method and system for autonomously suppressing solar glare of a high-orbit optical remote sensing satellite. Background Art

[0002] Glare is a strong radiation signal formed by sunlight reflected by the mirror surface elements of the sea surface. Its amplitude is much larger than the ocean target signal, and it is easy to cause optical imaging information saturation and distortion, which limits the optical imaging capability. In satellite remote sensing images, solar glare is generated in specific image areas, and the geometric characteristics of high-orbit optical remote sensing imaging will cause it to lose the ability to observe specific target areas within a specific time period due to the influence of solar glare, reducing the observation efficiency of remote sensing satellites.

[0003] For situations where the intensity of glare does not cause large-area pixel saturation of the imaging detector and only causes contamination interference to the imaging, glare correction and removal can be performed. Methods based on estimating the proportion of glare in the radiation received by the sensor and subtracting the glare from the received signal can be divided into two main categories: ① For large-scale water color remote sensing applications with a resolution of 100 to 1000m, glare is estimated and corrected based on the Cox-Munk sea surface statistical model, and is applied in sensors such as SeaWiFS and MERIS; ② For high-resolution remote sensing applications with a resolution of 1 to 10m, based on the good absorption characteristics of water in the near-infrared band and the fact that the radiation away from water in the near-infrared band is approximately zero, the intensity of the received glare radiation is estimated using near-infrared radiation and the glare is subtracted. This method is applied to remote sensing satellites such as IKONOS and AVIRIS. This method places higher demands on system design and subsequent image processing capabilities.

[0004] In applications where glare causes large-area pixel saturation in the detector, pixel information is easily lost and cannot be corrected, so the glare intensity must be suppressed. Traditional suppression methods mainly adopt "avoidance" and "elimination" strategies: ① "Avoidance" means avoiding areas with severe solar glare as much as possible during sensor detection; ② "Elimination" means eliminating pixels in remote sensing images that are severely polluted by solar glare and do not participate in subsequent information extraction. The "avoidance" strategy is limited by the sensor task requirements, and the "elimination" strategy will result in many data blank areas due to the elimination of a large number of pixels. Therefore, the application of these two glare suppression methods has great limitations.

[0005] As is known, optical polarization remote sensing, as a new type of imaging method for earth observation, has unique advantages in target detection and identification compared with traditional optical radiation remote sensing methods. It is used to weaken the interference of sea clutter glare, sea fog, and sky background scattered radiation, and solve some problems that traditional optical remote sensing cannot solve. It has great application and development potential. Based on the significant polarization characteristics of glare, domestic and foreign researchers have proposed some methods for glare suppression using polarization characteristics. For example, "Polarization Analysis of Solar Glare" (Journal of Infrared and Millimeter Waves, 2007, 26) proposed a method for solar glare suppression using a single polarizer. This method has a good weakening effect on glare when the observation zenith angle is large, but as the angle between the polarization direction and the horizontal polarizer position changes, its weakening effect gradually decreases; "Mid-infrared imaging system based on polarizers for detecting marine targets covered in sun glint" (Optics Express, 2016, 24) designed a visible light polarization detection system based on dual polarizers. The system can suppress glare interference to a certain extent, but the target polarization characteristics are greatly lost. The above suppression methods use a single or two polarizers to suppress and reduce solar glare. However, in actual onboard applications, a single or two angle polarizers cannot adapt well to the polarization characteristics of solar glare that changes with different seasons and time. If the polarizer angle adjustment mechanism is further added, the hardware complexity and cost will be further increased. Summary of the invention

[0006] In order to avoid the strong radiation interference of solar glare causing saturation of optical imaging detectors, thereby causing distortion of optical remote sensing satellite imaging, the present disclosure provides a method and system for actively suppressing solar glare for high-orbit optical remote sensing satellites, which solves the problem that high-orbit optical remote sensing satellites cannot obtain high-fidelity remote sensing images in the glare area. The method is applicable to high-orbit optical remote sensing satellites designed with polarizers and the satellites have agile maneuverability.

[0007] The present disclosure provides a method for autonomously suppressing solar glare of a high-orbit optical remote sensing satellite, comprising the following steps:

[0008] Determine the flare period and area for high-orbit imaging;

[0009] Obtain the imaging plan mission parameters, including the imaging time T0, and the latitude and longitude parameters of the mission target point (L0, B0), determine the corresponding satellite roll ψ, pitch angle ω, and the time t{ψ,ω} required for the satellite to move from the current position to the imaging target;

[0010] Conduct on-board mission conflict judgment;

[0011] Determine whether the imaging task is affected by flare. If so, then:

[0012] Instruct the camera to enter the polarization imaging mode, and the camera cuts the polarizer into the optical path;

[0013] Calculate the satellite yaw angle κ according to the imaging plan task parameters;

[0014] Determine whether the yaw angle exceeds the threshold θ0. If it does not exceed the threshold, perform the attitude maneuver {ψ, ω}, and perform 0° polarization imaging on the target at time T0;

[0015] If it exceeds, then according to the current time T and the attitude maneuver time t{κ}, judge T + t {ψ,ω} +t {κ} < T0. If it is satisfied, perform the attitude maneuver {ψ, ω, κ}, and perform precise polarization imaging on the target at time T0, with the polarization imaging angle κ; otherwise, perform the attitude maneuver {ψ, ω}, and perform 0° polarization imaging on the target at time T0.

[0016] Furthermore, the steps of determining the high-orbit imaging flare period and area, the specific method includes:

[0017] According to the high-orbit satellite orbital position A(X A ,Y A ,Z A ), the target point longitude and latitude P(L, B) and the imaging time T m , calculate the solar zenith angle θ s , the satellite observation angle θ v , and the difference between the solar azimuth angle and the observation azimuth angle

[0018] Calculate the target flare angle Θ according to the following formula glit :

[0019]

[0020] Traverse the annual time and the earth longitude and latitude grid, set the time step to 1 hour, and the target longitude and latitude are in a grid size of 1 degree, and calculate the set of flare angles {Θ glit} = F{X A ,Y A ,Z A , L, B, T m};

[0021] Taking the flare angle Θ glit not greater than 5° as the threshold, and at the same time satisfying θ s +θ v ∈ [101, 111] and ​As the judgment condition, the annual sea surface glare distribution interval envelope is obtained as [T min ,T max ] n , the regional range envelope is [L min ,L max ] n , [B min ,B max ] n , where n = 2, T min is the minimum value of Beijing time, T max is the maximum value in Beijing time, L min , B min is the minimum value of longitude and latitude, L max , B max The maximum value of longitude and latitude.

[0022] Furthermore, the step of determining the conflict of onboard missions specifically includes:

[0023] Assume that the current time is T and the camera imaging preparation time is t Camera , determine whether it satisfies:

[0024] T0-T>t{ψ,ω} and T0-T>t Camera ;

[0025] If satisfied, there is no conflict and the subsequent steps are continued;

[0026] If not, the task has a conflict and cannot be executed, and the process ends.

[0027] Furthermore, the step of determining whether the imaging task is affected by glare is specifically performed as follows:

[0028] Calculate the target flare angle;

[0029] If the flare angle is ≤5° and:

[0030] If the target imaging time and longitude and latitude satisfy T0∈[T min ,T max ] n And L0∈[L min ,L max ] n And B0∈ [B min ,B max ] n ,

[0031] is affected by glare.

[0032] Furthermore, the step of calculating the satellite yaw angle κ according to the imaging plan mission parameters specifically includes:

[0033] In view of the process in which sunlight is reflected by the sea surface and enters the camera optical system, the polarization angle of the light beam incident on the camera optical system is calculated:

[0034]

[0035] Among them, R s and R p is the reflectance ratio of the s-light and p-light reflected by the sea surface. According to the Fresnel reflection formula, the reflectance ratio of the s-light and p-light reflected by the sea surface is:

[0036]

[0037]

[0038] The yaw angle that needs to be rotated on the satellite is κ = 90-β;

[0039] The above angles are all based on the east-west direction, with 0° parallel to the equator and clockwise as positive.

[0040] Furthermore, in the step of determining whether the yaw angle exceeds a threshold value θ0, the determination of θ0 is based on the degree of solar glare peeling:

[0041] The light intensity observed after passing through the analyzer at an angle θ with the vibration direction of the incident polarized light is

[0042]

[0043] Among them, I0 is the linear polarization intensity of the reflected light, and P is the degree of polarization;

[0044] when , θ0=θ=5°, that is, the threshold θ0 is taken as 5°.

[0045] The present disclosure also provides a solar glare active suppression system for a high-orbit optical remote sensing satellite, comprising:

[0046] Note module: used to obtain satellite imaging plan mission parameters and perform mission notes;

[0047] Task scheduling module: used to receive the satellite imaging plan task parameters, perform a series of related calculations and judgments, and issue corresponding control instructions, including: on-board task conflict judgment, whether the target is in the flare area, accurate flare angle calculation, polarization mode setting, satellite attitude angle and maneuvering time calculation;

[0048] Attitude maneuvering module: used to control the satellite to perform attitude maneuvers and maintain attitude according to the calculated attitude angle, so that the camera's visual axis directly points to the target point;

[0049] A camera polarization module, used to cut a polarizer into / out of a camera imaging optical path according to instructions, wherein the polarizer is a single polarizer in a camera filter box component, and the installation orientation is such that the polarizer is perpendicular to the optical axis;

[0050] Camera imaging module: used to execute imaging startup instructions and image the target at a specified time;

[0051] The transmission of instructions and information between modules is completed by the on-board bus and on-board communication protocol.

[0052] The present invention provides a method and system for autonomously suppressing solar glare by a high-orbit optical remote sensing satellite. By pre-calculating the glare area, the necessity and feasibility of the autonomous glare suppression task are accurately selected. The satellite's attitude maneuverability is then used to rotate the angle to achieve polarization imaging, effectively suppressing solar glare. At the same time, the imaging efficiency loss caused by traditional methods such as avoidance and elimination is avoided, solving the problem that high-orbit optical remote sensing satellites cannot obtain high-fidelity remote sensing images in the glare area.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] (1) Taking advantage of the strong polarization of solar glare, the solar glare can be suppressed by adding polarizers and rotating the angle through the satellite's attitude maneuverability, thus avoiding the loss of imaging performance caused by avoidance and elimination methods;

[0055] (2) No need to add complex control devices to accurately control the rotation angle of the polarizer, the satellite can be directly adjusted to achieve fidelity imaging under glare suppression;

[0056] (3) By calculating the glare area in advance and transmitting it to the satellite, the prerequisites for the glare suppression task are predicted, the satellite's autonomous glare suppression task process is optimized, and the demand for onboard computing is reduced;

[0057] (4) By determining the minimum yaw rotation angle for glare suppression, the satellite can achieve autonomous glare suppression at the lowest cost, thus reducing the satellite cost-effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the change of polarization degree in reflected light with incident angle;

[0059] Figure 2 It is a schematic diagram of the process of the high-orbit optical remote sensing satellite glare suppression method disclosed in the present invention;

[0060] Figure 3 This is a schematic diagram for calculating the observation zenith angle and the observation azimuth angle;

[0061] Figure 4A schematic diagram of the rotation of the glare suppression polarizer of the high-orbit optical remote sensing satellite disclosed in the present invention;

[0062] Figure 5 Schematic diagram of the changes in the degree of solar glare stripping in high-orbit optics throughout the year. DETAILED DESCRIPTION

[0063] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0064] The present invention provides an autonomous glare suppression method for a high-orbit optical remote sensing satellite, and an exemplary implementation process is described as follows.

[0065] Step 1: Determine the time period and area where the flare of high-orbit satellites appears.

[0066] The reflectivity of water is generally around 0.2, but its reflectivity varies greatly with the observation angle. Under certain observation conditions, the reflectivity of water can even exceed 0.9, which will cause solar glare. Solar glare can cause sensor saturation and seriously affect the observation of other objects.

[0067] When the solar azimuth and observation azimuth of a certain point on the sea surface are on the same principal plane at different sides (i.e., when the satellite-sun azimuth angle is about 180°), the linear polarization in the reflected light from the water surface will increase with the increase of the incident angle, and then decrease after the incident angle reaches the Brewster angle of water, such as Figure 1 shown.

[0068] The Brewster angle calculation formula is as follows:

[0069]

[0070] Where n2 is the refractive index of the refracting side, n1 is the refractive index of the incident side, and assuming that the refractive index of water is 1.33, the Brewster angle of the sea surface is 53°. The present invention takes the principal plane ±5° (i.e., the sun-satellite azimuth angle 180°±5°) and the Brewster angle ±5° as necessary conditions for easy glare generation.

[0071] 1.1) Calculate the solar zenith angle θ based on the geometric position relationship between the high-orbit satellite, the sun and the target point s , satellite observation angle θ v , and the difference between the solar azimuth and the observed azimuth

[0072] Solar zenith angle θ s The formula for calculating the cosine value of is:

[0073] cosθ s =sin(sinB0sinδ+cosB0cosδcosφ)

[0074] Solar azimuth The formula for calculating the cosine value of is:

[0075]

[0076] In the above two formulas, δ is the solar declination, φ is the solar hour angle, and the calculation formula for solar declination δ is:

[0077] δ=0.3723+23.2567sinθ+0.1149sin2θ-0.1712sin3θ-0.7568cosθ+0.2656cos2θ+0.0201cos3θ

[0078] Among them, θ is the sun angle, and its calculation formula is:

[0079]

[0080] in:

[0081] t sun =N+ΔN-N0

[0082] Among them, N is the accumulated day, that is, the serial number of the date corresponding to the imaging moment in the year, and ΔN is the accumulated day correction value.

[0083] Observation zenith angle θ v With observation azimuth The calculation method, combined with the Figure 3 Note: This is done in the WGS84 coordinate system, where the feature P is converted into the WGS84 coordinate P (X0, Y0, Z0) through longitude and latitude, and the satellite coordinate A (X A ,Y A ,Z A ) can be obtained by orbital extrapolation, where OP is the line between the center of the earth and the object, plane α is the tangent plane of the object relative to the earth, N is the intersection of plane α and the Z axis, B is the projection point of satellite A on plane α, and C is the projection point of satellite A on the normal vector of plane α. Therefore, the true north direction of the object point P is is the projection of the line connecting satellite A and object P on plane α. Specifically:

[0084]

[0085] in,

[0086] Observation azimuth The formula for calculating the cosine value is:

[0087]

[0088] Among them, the coordinates of point N can be calculated through geometric relationship Where R is the radius of the Earth, then and In addition, there are geometric relationships:

[0089]

[0090] The observation azimuth can be obtained according to the cosine value calculation formula.

[0091] The flare angle θ is calculated according to the following formula: glit :

[0092]

[0093] Traverse the full year time and the earth's longitude and latitude grid, set the time step to 1 hour, the target longitude and latitude with a grid size of 1 degree, and calculate the set of flare angles {Θ glit}=F{X A ,Y A ,Z A , L, B, T};

[0094] 1.2) Flare angle θ glit The threshold is no greater than 5° and satisfies θ s +θ v ∈[101,111] and As the judgment condition, the envelope of the annual sea surface glare distribution period is obtained as [T min ,T max ] n , the regional range envelope is [L min ,L max ] n , [B min ,B max ] n , where n = 2, T min is the minimum value of Beijing time, T max is the maximum value in Beijing time, L min , B min is the minimum value of longitude and latitude, L max , B max The maximum value of longitude and latitude.

[0095] Taking the orbit altitude of 3600km, the fixed position of 120° and the whole year of 2019 as an example, the distribution area and time of sea surface glare can be calculated: the sea surface glare is concentrated in the east and west areas, with 120° east longitude as the center line, such as Figure 3 As shown:

[0096] The main area on the east side is (17°N, 159°E)-(21°S, 166°E).

[0097] The main area on the west side is (18°N, 73°E)-(21°S, 82°E).

[0098] In the area east of 120° east longitude, the flare appears from 4:00 to 7:00 (Beijing time), which is about 7:00 to 10:00 local time. In the area west of 120° east longitude, the flare appears from 17:00 to 20:00 (Beijing time), which is about 14:00 to 17:00 local time. The area where the flare appears every day is about 220,000 square kilometers.

[0099] Table 1 Distribution of sea surface glare throughout the year

[0100]

[0101]

[0102] Before the satellite is launched, the annual sea surface glare distribution period [T min ,T max ] n , Regional scope [L min ,L max ] n , [B min ,B max ] n Upload to the satellite service computer.

[0103] Step 2: Obtain satellite imaging mission parameters and register the mission

[0104] Get satellite imaging mission parameters: imaging time T0, longitude and latitude parameters of mission center point (L0, B0).

[0105] Step 3: The satellite service computer receives the satellite imaging plan mission parameters and performs on-board mission conflict judgment.

[0106] 3.1) According to the satellite orbital position coordinates at time T0 and the target longitude and latitude (L0, B0), the satellite sway ψ and pitch angle ω are calculated inversely, and the time t{ψ, ω} required for the satellite to move from the current position to point to the imaging target is obtained through the on-board attitude maneuverability lookup table;

[0107] 3.2) Let the current time be T and the camera imaging preparation time be t Camera , determine whether the conditions are met: T0-T >t{ψ,ω} and T0-T>t Camera ; If satisfied, execute the next step; if not satisfied, the task cannot be executed and the process ends.

[0108] Step 4, determine whether the satellite imaging mission is affected by glare:

[0109] Calculate the target flare angle according to formula (1);

[0110] Determine whether the target flare angle is ≤5° and whether the latitude and longitude of the imaging target is within the flare area: that is, T0∈[T min ,T max ] n And L0∈[L min ,L max ] n And B0∈[B min ,B max ] n ,

[0111] If yes, a polarization imaging mode setting instruction is sent to the camera, and the camera cuts the polarizer into the light path.

[0112] Step 5: The satellite computer calculates the satellite yaw angle κ based on T0 and the target longitude and latitude, which is used to realize the polarizer deflection angle κ

[0113] 5.1) Calculate the polarization angle of the light beam incident on the camera optical system when the sunlight is reflected by the sea surface and enters the camera optical system:

[0114]

[0115] Among them, R s and R p is the reflectance ratio of the s-light and p-light reflected by the sea surface. According to the Fresnel reflection formula, the reflectance ratio of the s-light and p-light reflected by the sea surface is:

[0116]

[0117]

[0118] 5.2) The yaw angle that the satellite needs to rotate is κ = 90°-β.

[0119] The above angles are all based on the east-west direction, with the direction parallel to the equator being 0° and clockwise being positive. Figure 4 shown.

[0120] Step 6, determine whether the yaw angle exceeds the threshold value θ0; if it does not exceed the threshold value, perform the attitude maneuver {ψ, ω}, and perform 0° polarization imaging of the target at time T0; otherwise, execute the next step;

[0121] The determination of θ0 is based on the degree of solar glare stripping:

[0122]

[0123] Among them, I0 is the linear polarization intensity of the reflected light, and P is the degree of polarization.

[0124] 6.1) When θ is 0°, the solar incident plane is in the equatorial plane

[0125] When considering a large solar incidence angle (>50°), the specular reflection phenomenon is likely to occur, and the degree of polarization stripping is as shown in the following table. It can be seen from the table that the 0° horizontal polarization can play a good role in suppressing the solar specular reflection with the incident plane in the equatorial plane.

[0126] Table 2 Analysis table of the degree of polarization stripping of sunlight

[0127] Sunlight incident angle / ° Polarization degree of water after reflection Light intensity after passing through the analyzer Degree of solar glare stripping / % 50 0.9849 <![CDATA[0.0075I0]]> 99.25 60 0.9264 <![CDATA[0.0368I0]]> 96.32 70 0.6436 <![CDATA[0.1782I0]]> 82.18 80 0.3121 <![CDATA[0.3439I0]]> 65.61

[0128] 6.2) When θ is not 0°

[0129] Considering the summer solstice, winter solstice, etc., the sun does not shine directly on the equator, and the solar incident plane is not in the equatorial plane. According to the different annual specular reflection distribution regions, the change range of the angle between the polarization direction of the polarizer and the horizontal position of the camera is ±21°, and the stripping of solar specular reflection is as Figure 5 shown. It can be seen that the 0° polarizer setting can play a good role in suppressing the strong solar specular reflection throughout the year.

[0130] According to the calculation, when θ0 = θ = 5°, satisfying at this time, the threshold θ0 is set to 5°.

[0131] Step 7, obtain the attitude maneuver time t{κ} through the attitude maneuverability look-up table;

[0132] Step 8, determine whether T + t{ψ,ω} + t{κ} < T0. If it is satisfied, perform the attitude maneuver {ψ,ω,κ}, and perform precise polarization imaging on the target at the moment T0; otherwise, perform the attitude maneuver {ψ,ω}, and perform 0° polarization imaging on the target at the moment T0.

[0133] According to an embodiment of the solar specular reflection active suppression system of a geostationary optical remote sensing satellite of the present disclosure, it includes:

[0134] Mission upload module: Obtain the task parameters of the satellite imaging plan and perform mission upload: imaging time T0, target longitude and latitude;

[0135] Mission scheduling module: The satellite on-board computer receives the satellite imaging plan task parameters, performs on-board task scheduling, specular reflection angle calculation, and imaging mode judgment and decision-making;

[0136] Attitude maneuver module: The satellite performs attitude maneuver and attitude holding according to the calculated attitude angle, so that the camera optical axis directly points to the target point.

[0137] Camera polarization module: A single polarizer in the camera filter box, installed with the polarizer perpendicular to the optical axis; the polarizer spectral range is the visible and near-infrared spectral range, and the extinction ratio is 1000:1; the camera polarization module can cut the polarizer into / out of the camera imaging light path according to instructions.

[0138] Camera imaging module: The camera executes the imaging power-on instruction group, and the satellite accurately aligns with the target center point for imaging at T0.

[0139] In the process of glare suppression, the information flow relationship of the above five modules is:

[0140] The camera polarization module is installed in the filter box component of the camera subsystem before the satellite is launched.

[0141] Before imaging, the uplink injection module receives the satellite's "imaging plan mission uplink injection instruction", including the imaging time T0, the longitude and latitude parameters of the mission target point (L0, B0), and forwards it to the task scheduling module.

[0142] The task scheduling module determines on-board task conflicts, determines whether the target is in the flare area, calculates the precise flare angle, sets the polarization mode, calculates the satellite attitude angle and maneuvering time, etc. It sends instructions to the camera polarization module, attitude maneuvering module, and camera imaging module based on the calculation and judgment results.

[0143] After receiving the "polarization mode imaging setting" instruction from the task scheduling module, the camera polarization module cuts the polarizer into the light path and waits for imaging;

[0144] The attitude maneuvering module receives the instruction of "maneuver according to attitude {ψ, ω}" or "maneuver according to attitude {ψ, ω, κ}" from the task scheduling module, and adjusts the satellite attitude to make the camera point to the target point;

[0145] After receiving the "camera imaging on" instruction from the task scheduling module, the camera imaging module starts the camera and performs image output.

[0146] The transmission of instructions and information between different units is completed by the on-board bus and on-board communication protocol.

[0147] The present invention provides a method and system for autonomously suppressing solar glare by a high-orbit optical remote sensing satellite. The method does not require the addition of complex devices, but only requires the addition of a polarizing plate, and does not require precise control of its rotation angle. The method can effectively suppress solar glare by rotating the angle of the satellite's attitude maneuverability, thereby avoiding the loss of imaging efficiency caused by avoidance, elimination and other methods, and solving the problem that high-orbit optical remote sensing satellites cannot obtain high-fidelity remote sensing images in the glare area.

[0148] At the same time, the present invention adopts the method of pre-calculating the glare area and making multiple judgments before the task is executed, accurately selecting the necessity and feasibility of the autonomous glare suppression task, optimizing the satellite autonomous glare suppression task process, and reducing the satellite cost-effectiveness.

[0149] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for autonomously suppressing solar glare of a high-orbit optical remote sensing satellite, characterized in that: The following steps are involved: Determine the flare period and area for high-orbit imaging; Get imaging schedule task parameters, including imaging time T 0, and the latitude and longitude parameters of the mission target point ( L 0, B 0), determine the corresponding satellite roll ψ, pitch angle ω, and the time t{ψ,ω} required for the satellite to move from its current position to point to the imaging target; Conduct on-board mission conflict judgment; Determine whether the imaging plan task is affected by glare, if so, then: Instruct the camera to enter polarization imaging mode, and the camera cuts the polarizer into the light path; Calculating the satellite yaw angle κ according to the imaging plan mission parameters; Determine whether the yaw angle exceeds the threshold θ0. If it does not exceed the threshold, perform the attitude maneuver {ψ, ω}. T At time 0, the target is imaged with 0° polarization; If it exceeds, then according to the current time T , attitude maneuver time t{κ}, judge T+t {ψ,ω} +t {κ} < T 0, if it is satisfied, then perform the attitude maneuver {ψ,ω, κ}, in T At time 0, the target is accurately polarized and imaged with a polarization imaging angle of κ; otherwise, the attitude maneuver {ψ, ω} is performed. T At time 0, the target is imaged with 0° polarization; The step of calculating the satellite yaw angle κ according to the imaging plan mission parameters specifically includes: In the process of sunlight being reflected by the sea surface and entering the camera optical system, the polarization angle of the light beam incident on the camera optical system is calculated: in, and is the reflectance ratio of the s-light and p-light reflected by the sea surface. According to the Fresnel reflection formula, the reflectance ratio of the s-light and p-light reflected by the sea surface is: The yaw angle required to rotate the satellite is ; The above angles are all based on the east-west direction, with the direction parallel to the equator being 0° and clockwise being positive; Determining whether the yaw angle exceeds the threshold θ 0, the θ The determination of 0 is based on the degree of solar glare stripping: The angle between the incident polarized light and the vibration direction is θ The light intensity observed after passing through the analyzer at an angle is: in, I 0 is the intensity of linear polarization in the reflected light, P is the degree of polarization; when When ≤1%, θ 0 =θ=5° , that is, the threshold θ 0 is taken as 5°.

2. The method according to claim 1, characterized in that The step of determining the high orbit imaging flare period and area specifically includes: According to the high-orbit satellite orbital position A ( X A ,Y A ,Z A )、target point latitude and longitude P( L, B ) and imaging time T , calculate the solar zenith angle , Satellite observation angle , and the difference between the solar azimuth and the observed azimuth ; Calculate the flare angle according to the following formula : Traverse the full year time and the earth's longitude and latitude grid, set the time step to 1 hour, the target longitude and latitude with a grid size of 1 degree, and calculate the set of flare angles { }= F{ X A ,Y A ,Z A , L, B, T }; Flare Angle The threshold is no greater than 5° and meets the following conditions: and To determine the conditions, the annual sea surface glare distribution interval envelope is obtained as [ T min ,T max ] n , the regional range envelope is [ L min , L max ] n 、[ B min , B max ] n ,in, n =2, T min is the minimum value of Beijing time, T max is the maximum value of Beijing time. L min、 B min is the minimum value of longitude and latitude, L max、 B max The maximum value of longitude and latitude.

3. The method according to claim 1, characterized in that The step of determining the conflict of on-board missions specifically includes: Assume the current satellite time is T , the camera imaging preparation time is t Camera , determine whether it satisfies: T0-T> t{ψ,ω}and T0-T>t Camera ; If the conditions are met, there is no conflict and the subsequent steps will continue; if not, there is a conflict in the task and it cannot be executed, and the process ends.

4. The method according to claim 2, characterized in that: The specific method of determining whether the imaging plan task is affected by glare is as follows: Calculate the target flare angle; If the flare angle is ≤ 5° and: If the target imaging time and longitude and latitude meet T 0 ∈ [ T min ,T max ] n and L 0 ∈ [ L min , L max ] n and B 0 ∈ [ B min , B max ] n , is affected by glare.

5. A high-orbit optical remote sensing satellite solar glare active suppression system, used to implement any of the methods described in claims 1-4, characterized in that: include: Note module: used to obtain satellite imaging plan mission parameters and perform mission notes; Task scheduling module: used to receive the satellite imaging plan task parameters, perform a series of related calculations and judgments, and issue corresponding control instructions, including: on-board task conflict judgment, whether the target is in the flare area, accurate flare angle calculation, polarization mode setting, satellite attitude angle and maneuvering time calculation; Attitude maneuvering module: used to control the satellite to perform attitude maneuvers and maintain attitude according to the calculated attitude angle, so that the camera's visual axis directly points to the target point; A camera polarization module, used to cut a polarizer into / out of a camera imaging optical path according to instructions, wherein the polarizer is a single polarizer in a camera filter box component, and the installation orientation is such that the polarizer is perpendicular to the optical axis; Camera imaging module: used to execute imaging startup instructions and image the target at a specified time; The transmission of instructions and information between modules is completed by the on-board bus and on-board communication protocol.

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