On-orbit compensation method for optical remote sensing satellite earth observation line-of-sight angle

Abstract

The application provides an on-orbit compensation method for a line-of-sight angle of an optical remote sensing satellite for earth observation, and the method comprises the following steps: obtaining an atmospheric refraction index in an optical band; obtaining a partial derivative of the atmospheric refraction index with respect to pressure and a partial derivative of the atmospheric refraction index with respect to temperature, and obtaining a calculation precision of an atmospheric refraction index model according to the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature; adaptively layering the atmosphere according to the calculation precision of the atmospheric refraction index model to obtain an adaptive height layer distribution of the atmosphere; and obtaining a line-of-sight angle deviation of the optical remote sensing satellite for earth observation by using a ray tracing method on the basis of the adaptive height layer distribution of the atmosphere, and compensating the line-of-sight angle of the optical remote sensing satellite for earth observation according to the line-of-sight angle deviation of the optical remote sensing satellite for earth observation. The application can solve the technical problem that the existing compensation method for the line-of-sight angle of the earth observation cannot meet the real-time high-precision calculation on the satellite.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical remote sensing satellites, and particularly relates to an on-orbit compensation method for a line-of-sight angle of an optical remote sensing satellite. BACKGROUND

[0002] With the gradual development of satellite technology, optical remote sensing satellites are constantly pursuing higher resolution, higher positioning accuracy, faster dynamic response and on-orbit real-time processing capability. When a high-resolution optical remote sensing satellite observes the earth, the incident light passes through the atmosphere with uneven density, resulting in a line-of-sight angle deviation. The geometric positioning error caused by this atmospheric refraction error far exceeds a pixel, which seriously restricts the high-precision geometric positioning capability of the optical remote sensing satellite.

[0003] In the prior art, in order to weaken the influence of atmospheric refraction on the geometric positioning of the optical remote sensing satellite, the traditional method divides the atmosphere into equal and uniform layers and uses the ray tracing method to calculate the line-of-sight angle deviation caused by atmospheric refraction, thereby realizing the compensation of the line-of-sight angle for earth observation. In order to meet the high-precision requirement, the number of atmospheric layer heights to be divided by this method is increasing, and the demand for calculation amount is increasing. Due to the limited on-board resources, it is difficult to meet the on-orbit real-time calculation requirement.

[0004] Therefore, the prior art cannot meet the on-orbit high-precision compensation requirement of the line-of-sight angle for earth observation, and it is necessary to develop related algorithms that take into account high precision and real-time performance suitable for on-orbit real-time processing. SUMMARY

[0005] The present application provides an on-orbit compensation method for a line-of-sight angle for earth observation of an optical remote sensing satellite, which can solve the technical problem that the compensation method for the line-of-sight angle for earth observation in the prior art cannot meet the on-orbit real-time high-precision calculation.

[0006] According to an aspect of the present application, an on-orbit compensation method for a line-of-sight angle for earth observation of an optical remote sensing satellite is provided, which comprises:

[0007] obtaining an atmospheric refraction index in an optical band;

[0008] obtaining a partial derivative of the atmospheric refraction index with respect to pressure and a partial derivative of the atmospheric refraction index with respect to temperature, and obtaining the calculation accuracy of the atmospheric refraction index model according to the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature;

[0009] adaptively layering the atmosphere according to the calculation accuracy of the atmospheric refraction index model, to obtain an adaptive height layer distribution of the atmosphere;

[0010] On the basis of the adaptive height layer distribution of the atmosphere, the ray tracing method is used to obtain the line-of-sight angle deviation of the optical remote sensing satellite for the earth observation, and the line-of-sight angle of the optical remote sensing satellite for the earth observation is compensated according to the line-of-sight angle deviation of the optical remote sensing satellite for the earth observation.

[0011] Preferably, the adaptive height layer distribution of the atmosphere is obtained by adaptively dividing the atmosphere according to the calculation accuracy of the atmospheric refraction index model, including:

[0012] The atmosphere is uniformly divided along the height direction according to the preset height, and the atmospheric refraction index variation of each height layer is obtained.

[0013] The atmospheric refraction index variations of each height layer are sequentially added in order from the highest height layer to the lowest height layer, after each addition, the current cumulative value is compared with the calculation accuracy of the atmospheric refraction index model, if the current cumulative value is less than the calculation accuracy of the atmospheric refraction index model, the next addition is continued, if the current cumulative value is greater than or equal to the calculation accuracy of the atmospheric refraction index model, the height corresponding to the beginning of the addition to the current height is taken as an adaptive height layer, and the next addition is performed after the current cumulative value is cleared, until the height of the atmosphere is the height of the lowest height layer, thereby obtaining the adaptive height layer distribution of the atmosphere.

[0014] Preferably, the calculation accuracy of the atmospheric refraction index model is obtained according to the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature, including:

[0015] The size of the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature is compared.

[0016] The larger value of the two is taken as the calculation accuracy of the atmospheric refraction index model.

[0017] Preferably, the ray tracing method is used to obtain the line-of-sight angle deviation of the optical remote sensing satellite for the earth observation, including:

[0018] The initial incidence angle of the observation light ray incident to the first adaptive height layer is obtained.

[0019] The incidence angle and the refraction angle of each adaptive height layer are obtained according to the initial incidence angle.

[0020] The corresponding geocentric angle under the condition of atmospheric refraction is obtained according to the initial incidence angle, the incidence angle and the refraction angle of each adaptive height layer.

[0021] The actual line-of-sight angle for the earth observation is obtained according to the corresponding geocentric angle under the condition of atmospheric refraction.

[0022] The line-of-sight angle deviation of the optical remote sensing satellite for the earth observation is obtained according to the actual line-of-sight angle for the earth observation and the line-of-sight angle for the earth observation under the condition of atmospheric refraction.

[0023] Preferably, the initial incidence angle is obtained by the following formula:

[0024]

[0025] The incidence angle of each adaptive height layer is obtained by the following formula:

[0026]

[0027] The refraction angle of each adaptive height layer is obtained by the following formula:

[0028]

[0029] The corresponding geocentric angle with atmospheric refraction is obtained by the following formula:

[0030]

[0031] The actual line-of-sight angle of observation on the earth is obtained by the following formula:

[0032]

[0033] The line-of-sight angle deviation of observation on the earth caused by atmospheric refraction is obtained by the following formula:

[0034] δ = β - γ

[0035] In the formula, i0 represents the initial incidence angle, Re represents the radius of the earth, H represents the satellite height, β represents the line-of-sight angle of observation on the earth with atmospheric refraction, r0 represents the geocentric distance of the initial layer adaptive height layer, ik represents the incidence angle of light in the k-1 layer adaptive height layer, ik+1 represents the incidence angle of light in the k layer adaptive height layer, rk represents the geocentric distance of the k layer adaptive height layer, nk-1 represents the refractive index of the k-1 layer adaptive height layer, nk represents the refractive index of the k layer adaptive height layer, θk represents the refraction angle of light in the k layer adaptive height layer, θ0 represents the corresponding geocentric angle of the initial layer with atmospheric refraction, θk represents the corresponding geocentric angle of the k layer with atmospheric refraction, γ represents the actual line-of-sight angle of observation on the earth, and δ represents the line-of-sight angle deviation of observation on the earth caused by atmospheric refraction. k-1 k k k-1 k k

[0036] Preferably, the atmospheric refraction index of the optical band is obtained by the following formula:

[0037]

[0038] ​​​​​​​​In the formula, N represents the atmospheric refraction index of the optical waveband, N gaxs , N gws respectively represent the atmospheric refraction index caused by dry air and water vapor, ρ a , ρ w respectively represent the actual dry air density and water vapor density, ρ axs respectively represent the dry air density under standard atmospheric pressure, ρ ws represents the water vapor density under the condition of 20℃ temperature, 1333Pa pressure and 1 relative humidity.

[0039] According to another aspect of the present application, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above methods when executing the computer program.

[0040] According to the technical solution of the present application, the atmospheric layer is adaptively layered according to the calculation accuracy of the atmospheric refraction index model, the adaptive height layer distribution of the atmospheric layer is obtained, and the line-of-sight angle deviation of the optical remote sensing satellite for earth observation is obtained based on the adaptive height layer distribution of the atmospheric layer, so as to realize high-precision compensation of the line-of-sight angle of the optical remote sensing satellite for earth observation, and the calculation time is greatly reduced, thereby providing technical support for realizing on-orbit real-time positioning on the satellite. In addition, compared with the traditional equal-interval layering of the atmospheric layer, under the condition that the uncontrolled geometric positioning accuracy of the optical image is equivalent, the method of the present application can greatly reduce the number of atmospheric layer layers, and effectively improve the real-time performance of satellite on-orbit processing. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings included to provide a further understanding of the embodiments of the present application and constitute a part of the specification, illustrate embodiments of the present application and together with the text description serve to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0042] Figure 1 A flowchart of an on-orbit compensation method for line-of-sight angle of optical remote sensing satellite for earth observation is shown according to an embodiment of the present application;

[0043] Figure 2 A schematic diagram of optical remote sensing satellite for earth observation is shown according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other in the case of no conflict. The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component and / or combinations thereof.

[0046] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the various examples are not limiting of the scope of the present application. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and not of limitation. The detailed description of the technology, methods and devices known to those of ordinary skill in the art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so that once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0047] As Figure 1 shown, the present application provides an on-orbit compensation method for star-on-ground observation line angle of an optical remote sensing satellite, the method comprising:

[0048] S10, obtaining an atmospheric refraction index of an optical band;

[0049] S20, obtaining the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature, and obtaining the calculation accuracy of the atmospheric refraction index model according to the partial derivative of the atmospheric refraction index with respect to pressure and the partial derivative of the atmospheric refraction index with respect to temperature;

[0050] S30, adaptively layering the atmospheric layer according to the calculation precision of the atmospheric refraction index model to obtain an adaptive height layer distribution of the atmospheric layer;

[0051] S40, obtaining a line of sight angle deviation of the optical remote sensing satellite for earth observation by using a ray tracing method on the basis of the adaptive height layer distribution of the atmospheric layer, and compensating the line of sight angle of the optical remote sensing satellite for earth observation according to the line of sight angle deviation of the optical remote sensing satellite for earth observation.

[0052] According to the adaptive layering of the atmospheric layer according to the calculation precision of the atmospheric refraction index model, the adaptive height layer distribution of the atmospheric layer is obtained, and the line of sight angle deviation of the optical remote sensing satellite for earth observation is obtained on the basis of the adaptive height layer distribution of the atmospheric layer, so that the high-precision compensation of the line of sight angle of the optical remote sensing satellite for earth observation is realized, the calculation time is greatly reduced, and technical support is provided for realizing on-orbit real-time positioning on the satellite. In addition, compared with the traditional equal-interval layering of the atmospheric layer, under the condition that the uncontrolled geometric positioning precision of the optical image is equivalent, the method of the patent can greatly reduce the number of atmospheric layer layers, and effectively improve the real-time performance of satellite on-orbit processing.

[0053] According to an embodiment of the present application, in S10 of the present application, the atmospheric refraction index of the optical band is obtained according to the theoretical expression form of Ciddor-Owens as follows:

[0054]

[0055] In the formula, N represents the atmospheric refraction index of the optical band, N gaxs , N gws respectively represent the atmospheric refraction indexes caused by dry air and water vapor, ρ a , ρ w respectively represent the actual dry air density and water vapor density, ρ axs respectively represent the dry air density under standard atmospheric pressure, and ρ ws represents the water vapor density under the condition of 20℃ temperature, 1333Pa pressure and 1 relative humidity.

[0056] In the present embodiment, the atmospheric refraction index N gaxs caused by dry air under standard atmospheric pressure is as follows:

[0057]

[0058] Wherein, k0=238.0185 μm -2 , k1=5792105 μm -2 , k2=57.362 μm -2 , k3=167917 μm -2 , and λ is the wavelength in vacuum (unit: μm), χ cis the content of CO2 in the atmosphere (in ppm, generally assumed to be χ c = 375 ppm).

[0059] The atmospheric refraction index N gws caused by water vapor at standard atmospheric pressure is:

[0060]

[0061] where ω0= 295.235, ω1= 2.6422 μm 2 , ω2= -0.032380 μm 4 , and ω3= 0.004028 μm 6 .

[0062] In actual conditions, the dry atmospheric density ρ a is:

[0063]

[0064] where P is the pressure in actual conditions, M d = 0.0289632 kg·mol -1 is the molar mass of dry air, χ w = 0 is the relative humidity, R = 8.314510 J·mol -1 · K -1 is the universal gas constant; T = 273.15 + t is the absolute temperature in actual conditions, t is the temperature in degrees Celsius in actual conditions; and Z is the compressibility factor in actual gas conditions, calculated by:

[0065]

[0066] where

[0067] a0= 1.58123 x 10 -6 K·Pa -1

[0068] a1= -2.9331 x 10 -8 Pa -1

[0069] a2= 1.1043 x 10 -10 K -1 · Pa -1

[0070] b0= 5.707 x 10 -6 K·Pa -1

[0071] b1= -2.051 x 10 -8 Pa -1

[0072] c0=1.9898×10 -4 K·Pa -1

[0073] d0=1.83×10 -11 K 2 ·Pa -2

[0074] e0=-0.765×10 -8 K 2 ·Pa -2 .

[0075] At standard atmospheric pressure, the density of dry air is ρ axs for:

[0076]

[0077] in, is the absolute temperature under standard atmospheric pressure, P d =101325pa.

[0078] Similarly, the actual water vapor density ρ w for:

[0079]

[0080] Among them, M w =0.018015kg·mol -1 is the molar mass of water vapor, χ w =1 is relative humidity.

[0081] In T w =293.15K (ie t w =20℃), P w =1333Pa and χ w =1 water vapor density ρ ws The calculation formula is:

[0082]

[0083] in,

[0084] According to one embodiment of the present invention, based on the Ciddor-Owens atmospheric refractive index calculation model, it can be known that the atmospheric refractive index is affected by multiple factors such as wavelength, temperature, air pressure, humidity, and CO2 content. The influence of a single factor on the atmospheric refractive index is further calculated under standard atmospheric environment conditions. The calculation process is not repeated here.

[0085] Finally, it can be seen that atmospheric pressure and temperature have a significant impact on the atmospheric refractive index. Therefore, the present invention obtains the calculation accuracy of the atmospheric refractive index model based on the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature, specifically including:

[0086] S21. Compare the magnitudes of the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature.

[0087] S22. The larger value of the two is used as the calculation accuracy of the atmospheric refractive index model.

[0088] According to an embodiment of the present invention, in S30 of the present invention, adaptively stratifying the atmosphere according to the calculation accuracy of the atmospheric refractive index model to obtain the adaptive altitude layer distribution of the atmosphere includes:

[0089] S31, uniformly stratifying the atmosphere along the height direction according to a preset height, and obtaining the change in the atmospheric refractive index of each height layer;

[0090] S32. Accumulate the atmospheric refractive index changes of each altitude layer in sequence from the highest altitude layer to the lowest altitude layer. After each accumulation, compare the current accumulated value with the calculation accuracy of the atmospheric refractive index model. If the current accumulated value is less than the calculation accuracy of the atmospheric refractive index model, continue to the next accumulation. If the current accumulated value is greater than or equal to the calculation accuracy of the atmospheric refractive index model, take the altitude corresponding to the start of accumulation to the current altitude as an adaptive altitude layer, and reset the current accumulated value to zero before performing the next accumulation until the atmospheric layer altitude reaches the lowest altitude layer altitude, thereby obtaining the atmospheric layer adaptive altitude layer distribution.

[0091] For example, assume that the atmospheric layer height is 120km, and the atmosphere is evenly layered at a minimum height of 50m, and the atmospheric refractive index N of each altitude layer is calculated. i and the change in atmospheric refractive index ΔN i Further iterative calculation is performed from the initial height of 120km to calculate the cumulative value of the change in atmospheric refractive index like If the calculation accuracy ε of the atmospheric refractive index model is less than ε, continue to accumulate the atmospheric refractive index change of the next altitude layer; The calculation accuracy ε of the atmospheric refractive index model is greater than or equal to the current j-th layer height H j Set to the latest adaptive altitude layer H k , and Reset to 0 and continue the next iterative calculation until the atmospheric height is 0, thereby obtaining the atmospheric adaptive height layer distribution.

[0092] Assuming that each adaptive height layer obtained by the above method has the same atmospheric density, where the atmospheric density is dry atmospheric density or water vapor density, the light ray only refracts at the interface of adjacent layers and follows the Snell refraction law, and the optical remote sensing satellite's line-of-sight angle deviation for ground observation is obtained by ray tracing.

[0093] In the embodiment, as shown in Figure 2 , the electromagnetic signal of the target P reaches the satellite S in the form of a broken line, and the corresponding line-of-sight angle is γ; the satellite locates the target point as P' according to the observation light ray, and the corresponding line-of-sight angle is β.

[0094] The specific calculation steps of obtaining the line-of-sight angle deviation of the optical remote sensing satellite for ground observation by ray tracing are as follows:

[0095] S41, calculate the initial incident angle and the refraction angle

[0096] According to the sine law, the initial incident angle of the observation light ray to the first adaptive height layer is:

[0097]

[0098] The light ray is refracted after entering the atmosphere, and the Snell formula is:

[0099] n0 sin i0=n1 sinθ1;

[0100] where n0 is the refractive index of vacuum, which is set to 1, and the initial refraction angle is:

[0101]

[0102] S42, calculate the incident angle and the refraction angle of each adaptive height layer

[0103] The atmosphere is divided into m layers, and since it is assumed that each layer of atmosphere is uniform, the light ray is a straight line in each layer of atmosphere, and according to the Bouquer formula:

[0104] r0n0 sin i0=r k n k sin i k =r m n m sin i m ;

[0105] Then the incident angle of each adaptive height layer is:

[0106]

[0107] The refraction angle of each adaptive height layer is:

[0108]

[0109] S43、Calculate the earth central angle deviation caused by atmospheric refraction

[0110] According to the ground observation line of sight angle in the presence of atmospheric refraction, the corresponding earth central angle in the absence of atmospheric refraction is obtained, and the formula is as follows:

[0111]

[0112] According to the initial incident angle, the incident angle and the refraction angle of each adaptive height layer, the corresponding earth central angle in the presence of atmospheric refraction is obtained, and the formula is as follows:

[0113]

[0114] According to the corresponding earth central angle in the absence of atmospheric refraction and the corresponding earth central angle in the presence of atmospheric refraction, the earth central angle deviation caused by atmospheric refraction is obtained, and the formula is as follows:

[0115]

[0116] S44、Calculate the line of sight angle deviation caused by atmospheric refraction of ground observation

[0117] According to the law of sines, the actual line of sight angle of ground observation is calculated:

[0118]

[0119] According to the actual line of sight angle of ground observation and the line of sight angle of ground observation in the presence of atmospheric refraction, the line of sight angle deviation of optical remote sensing satellite ground observation is obtained, and the formula is as follows:

[0120] δ=β-γ;

[0121] In the formula, i0 represents the initial incident angle, Re represents the radius of the earth, H represents the satellite height, β represents the line of sight angle of ground observation in the presence of atmospheric refraction, r0 represents the earth central distance of the initial layer adaptive height layer, i k-1 , ik respectively represent the incident angle of light in the k-1 layer, the k layer adaptive height layer, r k , respectively represent the earth central distance of the k-1 layer, the k layer adaptive height layer, n k , respectively represent the refractive index of the k-1 layer, the k layer adaptive height layer, θ k-1 , respectively represent the refractive angle of light in the k-1 layer, the k layer adaptive height layer, k , respectively represent the corresponding initial layer, the k layer earth central angle in the presence of atmospheric refraction, k , respectively represent the corresponding initial layer, the k layer earth central angle in the presence of atmospheric refraction, , respectively represent the corresponding initial layer, the k layer earth central angle in the presence of atmospheric refraction, represents a corresponding geocentric angle in the case of atmospheric refraction, m represents the total number of adaptive height layers, y represents an actual line-of-sight angle observed on the ground, d represents a line-of-sight angle deviation caused by atmospheric refraction observed on the ground, 1 represents an initial refraction angle, n1 represents a refractive index of a first adaptive height layer, represents a corresponding geocentric angle in the case of atmospheric refraction, m represents the total number of adaptive height layers, y represents an actual line-of-sight angle observed on the ground, d represents a line-of-sight angle deviation caused by atmospheric refraction observed on the ground, 1 represents an initial refraction angle, n1 represents a refractive index of a first adaptive height layer, represents a corresponding geocentric angle in the case of atmospheric refraction, m represents the total number of adaptive height layers, y represents an actual line-of-sight angle observed on the ground, d represents a line-of-sight angle deviation caused by atmospheric refraction observed on the ground, 1 represents an initial refraction angle, n1 represents a refractive index of a first adaptive height layer,

[0122] The application further provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above methods when executing the computer program.

[0123] In summary, the application provides an on-orbit compensation method for a line-of-sight angle observed on the ground by an optical remote sensing satellite, the atmospheric layer is adaptively layered according to the calculation accuracy of the atmospheric refraction index model, the adaptive height layer distribution of the atmospheric layer is obtained, and the line-of-sight angle deviation observed on the ground by the optical remote sensing satellite is obtained based on the adaptive height layer distribution of the atmospheric layer, so as to realize high-precision compensation of the line-of-sight angle observed on the ground by the optical remote sensing satellite, and the calculation time is greatly reduced, thereby providing technical support for realizing real-time positioning on the satellite on-orbit. In addition, compared with the traditional equal-interval layering of the atmospheric layer, the number of atmospheric layer layers can be greatly reduced, and the real-time performance of the satellite on-orbit processing can be effectively improved under the condition that the uncontrolled geometric positioning accuracy of the optical image is equivalent.

[0124] The part not described in detail in the application is the technology known to those skilled in the art.

[0125] In the description of the application, it should be understood that the orientation words such as "front, rear, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and in the absence of contrary indications, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the scope of protection of the application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0126] For purposes of the description hereinafter, spatial or directional terms, for example, "above", "below", "upper", "lower", and the like, can be used, and relate to the device as illustrated in the figures. However, it is to be understood that no absolute or relative orientation of the device is intended or implied, unless specifically described as such. Terms concerning attachments, coupling and the like, such as "connected" and "coupled" and the like, are to be construed in accordance with their normal meanings, that is, as referring to an indirect or direct connection or coupling. Any reference to "comprising" or "containing" is to be construed as meaning "comprising or containing, but not limited to". Any reference to "comprising" or "containing" is to be construed as meaning "comprising or containing, but not limited to".

[0127] In addition, it should be pointed out that the use of the terms "first", "second" and the like, to describe various elements in the claims, is merely intended to distinguish between two steps or entities of the application, and is not intended to limit the scope of the present application, unless specifically stated otherwise. Thus, the terms "first", "second", and the like, are not intended to limit the scope of the present application, unless specifically stated otherwise.

[0128] The preferred embodiments herein disclosed are not intended to limit the scope of the application, which is set forth in the claims hereinafter. Various changes in form and details of the application can be made without departing from the spirit and scope of the application. Therefore, the scope of the application is defined not by the detailed description of the preferred embodiments but by the appended claims.

Claims

1. An on-orbit compensation method for an optical remote sensing satellite's Earth observation sight angle, characterized in that: The method comprises: Get the atmospheric refractive index in the optical band; Obtaining the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature, and obtaining the calculation accuracy of the atmospheric refractive index model based on the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature; Adaptively stratify the atmosphere according to the calculation accuracy of the atmospheric refractive index model to obtain the adaptive altitude layer distribution of the atmosphere; Based on the adaptive altitude layer distribution of the atmosphere, the ray tracing method is used to obtain the line-of-sight angle deviation of the optical remote sensing satellite to the earth observation, and the line-of-sight angle of the optical remote sensing satellite to the earth observation is compensated according to the line-of-sight angle deviation of the optical remote sensing satellite to the earth observation.

2. The method according to claim 1, characterized in that The atmosphere is adaptively layered according to the calculation accuracy of the atmospheric refractive index model, and the adaptive altitude layer distribution of the atmosphere is obtained, including: The atmosphere is evenly layered along the height direction according to the preset height, and the change in the atmospheric refractive index of each height layer is obtained; The atmospheric refractive index changes of each altitude layer are accumulated in sequence from the highest altitude layer to the lowest altitude layer. After each accumulation, the current accumulated value is compared with the calculation accuracy of the atmospheric refractive index model. When the current accumulated value is less than the calculation accuracy of the atmospheric refractive index model, the next accumulation is continued; when the current accumulated value is greater than or equal to the calculation accuracy of the atmospheric refractive index model, the altitude corresponding to the start of accumulation to the current altitude is regarded as an adaptive altitude layer, and the current accumulated value is cleared to zero and the next accumulation is performed until the atmospheric layer altitude reaches the altitude of the lowest altitude layer, thereby obtaining the atmospheric layer adaptive altitude layer distribution.

3. The method according to claim 1, characterized in that The calculation accuracy of the atmospheric refractive index model obtained by the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature includes: Compare the magnitudes of the partial derivative of the atmospheric refractive index with respect to pressure and the partial derivative of the atmospheric refractive index with respect to temperature; The larger value of the two is taken as the calculation accuracy of the atmospheric refractive index model.

4. The method according to claim 1, wherein The line-of-sight angle deviation of an optical remote sensing satellite observing the Earth using the ray tracing method includes: Obtain the initial incident angle of the observation light incident on the first adaptive height layer; Obtain the incident angle and refraction angle of each adaptive height layer according to the initial incident angle; Obtain the corresponding geocentric angle under atmospheric refraction based on the initial incident angle, the incident angle and the refraction angle of each adaptive altitude layer; Obtain the actual sight angle for earth observation based on the corresponding geocentric angle under atmospheric refraction; The line of sight angle deviation of the optical remote sensing satellite to the earth is obtained based on the actual line of sight angle of the earth observation and the line of sight angle of the earth observation with atmospheric refraction.

5. The method according to claim 1, wherein The initial incident angle is obtained by the following formula: The incident angle of each adaptive altitude layer is obtained by the following formula: The refraction angle of each adaptive height layer is obtained by the following formula: The corresponding geocentric angle under atmospheric refraction is obtained by the following formula: The actual line of sight angle for ground observation is obtained by the following formula: The line of sight angle deviation caused by atmospheric refraction for Earth observation is obtained by the following formula: δ = β - γ; Where i0 represents the initial incident angle, Re represents the radius of the earth, H represents the satellite altitude, β represents the line of sight angle to the earth in the presence of atmospheric refraction, r0 represents the distance from the center of the earth to the initial adaptive altitude layer, i k-1 、i k They represent the incident angles of light at the k-1th layer and the kth adaptive height layer, r k Indicates the distance from the center of the earth to the kth adaptive altitude layer, n k-1 、n k Represent the refractive index of the k-1th layer and the kth adaptive height layer, θ k Indicates the refraction angle of the light at the kth adaptive height layer, They represent the geocentric angles of the initial layer and the kth layer respectively under the condition of atmospheric refraction. It represents the geocentric angle corresponding to the atmospheric refraction, m represents the total number of adaptive altitude layers, γ represents the actual line of sight angle for Earth observation, and δ represents the line of sight angle deviation caused by atmospheric refraction for Earth observation.

6. The method according to claim 1, characterized in that The atmospheric refractive index in the optical band is obtained by the following formula: Where N represents the atmospheric refractive index in the optical band, N gaxs 、N gws Represent the atmospheric refractive index of dry atmosphere and water vapor respectively, ρ a , ρ w They represent the actual dry air density and water vapor density, ρ axs They represent the dry air density at standard atmospheric pressure, ρ ws It represents the water vapor density at a temperature of 20°C, a pressure of 1333 Pa, and a relative humidity of 1.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 6 is implemented.

Images