Single-star target line-of-sight atmospheric refraction correction method and system based on multi-spectral ranging

Abstract

The application discloses a single-star target line-of-sight atmospheric refraction correction method and system based on multi-spectral ranging, relates to the field of atmospheric refraction processing, and comprises the following steps: determining a target radiation intensity ratio based on two radiation intensities on different wave bands at the same time; acquiring observation lines of sight of a satellite on a measured target on different wave bands at the same time, and performing light track tracking to obtain light track trajectories; determining a target grid through by each light track trajectory from an atmospheric grid model, and determining an extinction coefficient of each target grid; combining a radiation intensity calculation formula to construct a target function of a radiation intensity ratio with respect to a height of a target distance from the ground; determining a target height of the measured target distance from the ground based on the target function and the target radiation intensity ratio; determining the position of the measured target according to a track point matched with the target height in each light track trajectory; and combining the position of the satellite to determine a line-of-sight vector after atmospheric refraction correction, so that high-precision atmospheric refraction correction under single-star observation conditions is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of atmospheric refraction processing, and particularly relates to a single-star target line-of-sight atmospheric refraction correction method and system based on multi-spectral ranging. BACKGROUND

[0002] Atmospheric refraction is a very common phenomenon, and its size depends on the direction of light incidence and the density distribution of the atmosphere. The observation target of a satellite is in the atmosphere, and when the line-of-sight pointing of the satellite to the observation target is determined based on the imaging image of the observation target, due to the existence of atmospheric refraction, the line-of-sight determination process will be deviated, thereby causing a false target. Therefore, how to correct the atmospheric refraction of the observation line-of-sight has become the focus of attention. The traditional atmospheric refraction correction method basically depends on the known spatial position of the target, and then the atmospheric refraction is corrected based on the spatial position of the target. However, under the condition of single-satellite observation, it is difficult to accurately obtain the spatial position of the target, and therefore the accuracy of atmospheric refraction correction of the observation line-of-sight is low. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a single-star target line-of-sight atmospheric refraction correction method and system based on multi-spectral ranging, which can more accurately determine the position of the measured target and realize high-precision atmospheric refraction correction under the condition of single-satellite observation. The specific scheme is as follows:

[0004] In a first aspect, the present application provides a single-star target line-of-sight atmospheric refraction correction method based on multi-spectral ranging, comprising:

[0005] Obtaining the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the measured target at different wavebands at the same time, and determining the target radiation intensity ratio based on the first radiation intensity and the second radiation intensity;

[0006] Obtaining the observation line-of-sight of the satellite to the measured target at different wavebands at the same time, and performing light trace tracking on each observation line-of-sight to obtain the corresponding light trace trajectory;

[0007] Determining the target grid through by each light trace trajectory from a preset atmospheric grid model, and determining the extinction coefficient of each target grid;

[0008] Using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through by each light trace trajectory, constructing a target function of the radiation intensity ratio with respect to the height of the target from the earth's surface;

[0009] Determining the target height of the measured target from the earth's surface based on the target function and the target radiation intensity ratio;

[0010] According to a trajectory point in each of the light ray tracing trajectories that matches the height of the target, a position of the measured target is determined, and an atmospheric refraction corrected line-of-sight vector is determined based on the position of the measured target and a position of the satellite.

[0011] Optionally, the measured target and the satellite are located in a high-density atmospheric layer and a low-density atmospheric layer, respectively; the high-density atmospheric layer is a region in the atmospheric layer within a preset height from the surface of the earth; and the low-density atmospheric layer is a region in the atmospheric layer outside the preset height from the surface of the earth.

[0012] Optionally, the light ray tracing is performed on each of the observation lines-of-sight to obtain a corresponding light ray tracing trajectory, including:

[0013] determining an intersection point between each of the observation lines-of-sight after atmospheric refraction and each atmospheric sub-layer; each of the atmospheric sub-layers is obtained by layering the high-density atmospheric layer;

[0014] based on the longitude and latitude of each of the intersection points and the layer height of the corresponding atmospheric sub-layer, determining the coordinates of each of the intersection points;

[0015] connecting and smoothing each of the intersection points based on the coordinates of each of the intersection points to obtain a corresponding light ray tracing trajectory.

[0016] Optionally, the construction process of the preset atmospheric gridding model includes:

[0017] dividing the high-density atmospheric layer into a plurality of grids according to longitude, latitude and height;

[0018] based on the pre-published global aerosol optical thickness and the height of each grid from the surface of the earth, calculating the extinction coefficient of the plurality of grids;

[0019] based on the plurality of grids and the extinction coefficient of the plurality of grids, constructing the preset atmospheric gridding model.

[0020] Optionally, the construction of the objective function of the ratio of the radiation intensity with respect to the height of the target from the surface of the earth based on the preset radiation intensity calculation formula and the extinction coefficient of the target grid through which each of the light ray tracing trajectories passes, includes:

[0021] based on a preset radiation intensity calculation formula, determining a ratio formula of two radiation intensities of the infrared radiation at different wave bands at the same time; the preset radiation intensity calculation formula is an exponential calculation formula of the radiation intensity with respect to the distance of the infrared radiation from the measured target to a demarcation line and the extinction coefficient; the demarcation line is used to distinguish the high-density atmospheric layer and the low-density atmospheric layer;

[0022] constructing a target function of radiation intensity ratio about target height from the earth surface based on the optical extinction coefficient of each target grid through which the ray tracing trajectory passes and the distance of each ray tracing trajectory in each target grid;

[0023] Optionally, before the position of the target is determined according to the trajectory point in each ray tracing trajectory matching the target height, the method further comprises:

[0024] querying the trajectory point in each ray tracing trajectory based on the target height, and determining whether the trajectory point matching the target height is queried;

[0025] if not, performing trajectory point interpolation on each ray tracing trajectory based on the target height to obtain the trajectory point matching the target height.

[0026] Optionally, the method further comprises:

[0027] converting the position of the target and the position of the satellite into the earth-centered inertial coordinate system to obtain corresponding target coordinates and satellite coordinates;

[0028] subtracting the satellite coordinates from the target coordinates to obtain an initial line-of-sight vector;

[0029] normalizing the initial line-of-sight vector to obtain the line-of-sight vector corrected by atmospheric refraction.

[0030] In a second aspect, the present application provides a single-satellite target line-of-sight atmospheric refraction correction system based on multi-spectral ranging, comprising:

[0031] a radiation intensity ratio determination module configured to obtain first and second radiation intensities of infrared radiation emitted by a target at different wavelengths at the same time, and determine a target radiation intensity ratio based on the first and second radiation intensities;

[0032] a light trace tracking module configured to obtain observation lines of sight of a satellite to the target at different wavelengths at the same time, and perform light trace tracking on each observation line of sight to obtain corresponding ray tracing trajectories;

[0033] an optical extinction coefficient determination module configured to determine target grids through which each ray tracing trajectory passes from a preset atmospheric grid model, and determine the optical extinction coefficient of each target grid;

[0034] a target function construction module, configured to construct a target function of a radiation intensity ratio with respect to a target height from the Earth's surface based on an optical extinction coefficient of a target grid through by each of the light ray tracing trajectories by using a preset radiation intensity calculation formula;

[0035] a target height determination module, configured to determine the target height of the measured target from the Earth's surface based on the target function and the target radiation intensity ratio;

[0036] an atmospheric refraction correction module, configured to determine a position of the measured target according to a trajectory point in each of the light ray tracing trajectories matching the target height, and determine an atmospheric refraction corrected line-of-sight vector based on the position of the measured target and a position of the satellite.

[0037] Optionally, the single-satellite target line-of-sight atmospheric refraction correction system based on multi-spectral ranging further comprises:

[0038] a trajectory point query unit, configured to query a trajectory point in each of the light ray tracing trajectories based on the target height, and determine whether the trajectory point matching the target height is queried;

[0039] a trajectory point interpolation unit, configured to, if not, perform trajectory point interpolation on each of the light ray tracing trajectories based on the target height to obtain the trajectory point matching the target height.

[0040] Optionally, the atmospheric refraction correction module comprises:

[0041] a coordinate system conversion unit, configured to convert the position of the measured target and the position of the satellite into an Earth-Centered Inertial coordinate system to obtain corresponding target coordinates and satellite coordinates;

[0042] an initial vector acquisition unit, configured to obtain an initial line-of-sight vector by subtracting the satellite coordinates from the target coordinates;

[0043] a normalization unit, configured to normalize the initial line-of-sight vector to obtain the atmospheric refraction corrected line-of-sight vector.

[0044] In the present application, the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the measured target at different wave bands at the same time are obtained, and the target radiation intensity ratio is determined based on the first radiation intensity and the second radiation intensity; the observation line of view of the satellite to the measured target at different wave bands at the same time is obtained, and the light trace tracking is performed on each observation line of view to obtain the corresponding light ray tracking trajectory; the target grid through by each light ray tracking trajectory is determined from the preset atmospheric grid model, and the extinction coefficient of each target grid is determined; the target function of the radiation intensity ratio with respect to the height of the target from the earth's surface is constructed by using the preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through by each light ray tracking trajectory; the target height of the measured target from the earth's surface is determined based on the target function and the target radiation intensity ratio; the position of the measured target is determined according to the trajectory point in each light ray tracking trajectory matching the target height, and the line of sight vector after atmospheric refraction correction is determined based on the position of the measured target and the position of the satellite.

[0045] As can be seen, the present application is different according to the atmospheric transmittance of infrared radiation at different wave bands, so the radiation intensity obtained at different wave bands is also different, and correspondingly, the target radiation intensity ratio determined based on the radiation intensity at different wave bands is also different; since the target radiation intensity ratio changes with the target height of the measured target from the earth's surface, the present application performs light trace tracking on the observation line of view of the satellite to the measured target to obtain the corresponding light ray tracking trajectory, and then constructs the target function of the radiation intensity ratio with respect to the height of the target from the earth's surface according to the extinction coefficient of the target grid through by each light ray tracking trajectory in the preset atmospheric grid model and the preset radiation intensity calculation formula, so as to more accurately determine the target height of the measured target from the earth's surface by using the target function and the known target radiation intensity ratio, and finally correct the line of sight vector of the satellite to the measured target by using the target height of the measured target from the earth's surface, to realize high-precision atmospheric refraction correction under single-satellite observation condition. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0047] Figure 1 A flow chart of a single-satellite target line of sight atmospheric refraction correction method based on multi-spectral ranging is disclosed in the present application.

[0048] Figure 2A schematic diagram of atmospheric refraction of starlight limb transmission disclosed in the application;

[0049] Figure 3 A zenith angle schematic diagram disclosed in the application;

[0050] Figure 4 A target grid schematic diagram through which a light ray tracking trajectory passes disclosed in the application;

[0051] Figure 5 A system structure schematic diagram of a single star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging disclosed in the application. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the application.

[0053] Traditional atmospheric refraction correction methods basically rely on knowing the spatial position of a target, and then performing atmospheric refraction correction based on the spatial position of the target. However, under the condition of single satellite observation, it is difficult to accurately obtain the spatial position of the target, so the accuracy of atmospheric refraction correction on the observation line of sight is low. Therefore, the application provides a single star target line-of-sight atmospheric refraction correction method based on multi-spectral ranging, which can more accurately determine the position of the measured target and realize high-precision atmospheric refraction correction under the condition of single satellite observation.

[0054] Referring to Figure 1 The embodiments of the application disclose a single star target line-of-sight atmospheric refraction correction method based on multi-spectral ranging, which comprises the following steps:

[0055] In step S11, the first radiation intensity and the second radiation intensity of infrared radiation emitted by the measured target at different wave bands at the same time are obtained, and the target radiation intensity ratio is determined based on the first radiation intensity and the second radiation intensity.

[0056] In the embodiments of the application, under the condition of single satellite observation, the first radiation intensity and the second radiation intensity of infrared radiation emitted by the measured target at different wave bands at the same time are obtained, and the target radiation intensity ratio is determined based on the ratio of the first radiation intensity and the second radiation intensity.

[0057] For example, at the same time, the first radiation intensity of infrared radiation emitted by the measured target at wave band i is obtained and the second radiation intensity of infrared radiation emitted by the measured target at wave band j is obtained At this time, the target radiation intensity ratio is .

[0058] It should be noted that the measured target and the satellite are located in a high-density atmosphere and a low-density atmosphere respectively; wherein the high-density atmosphere is a region in the atmosphere within a preset height from the surface of the earth; and the low-density atmosphere is a region in the atmosphere outside the preset height from the surface of the earth.

[0059] The embodiment of the present application considers that the atmospheric density is inversely proportional to the height from the surface of the earth, that is, the higher the height from the surface of the earth, the lower the atmospheric density, and the lower the atmospheric density, the smaller the atmospheric refractive index, and when the atmospheric refractive index is relatively small, the effect of atmospheric refraction can be approximately ignored. Therefore, in order to study atmospheric refraction, the present application selects a region in the atmosphere within a preset height from the surface of the earth as an observation region, and records it as a high-density atmosphere, wherein the preset height can be 80km, at this time the high-density atmosphere is a region that needs to consider atmospheric refraction. Correspondingly, the low-density atmosphere is a region outside the preset height from the surface of the earth, at this time the low-density atmosphere is a region that does not need to consider atmospheric refraction.

[0060] Further, in order to more accurately study atmospheric refraction, the high-density atmosphere can also be layered to obtain each atmospheric layer, so as to study the refraction between each atmospheric layer to analyze the refraction process of light transmission.

[0061] According to one specific embodiment, the present application uniformly layers the high-density atmosphere according to a preset uniform distance to obtain each atmospheric layer. For example, when the preset uniform distance is 1km, the high-density atmosphere is divided into one layer every 1km, thereby obtaining each atmospheric layer.

[0062] According to another specific embodiment, the present application divides the high-density atmosphere into two parts with a specified height as a boundary, wherein the specified height is less than the preset height, for example, 50km. Then, the part of the high-density atmosphere close to the surface of the earth is uniformly layered according to a first preset distance, and the other part of the high-density atmosphere away from the surface of the earth is uniformly layered according to a second preset distance, thereby obtaining each atmospheric layer. For example, when the first preset distance is 1km and the second preset distance is 2km, the part of the high-density atmosphere close to the surface of the earth (0~50km) is divided into one layer every 1km, and the other part of the high-density atmosphere away from the surface of the earth (50~80km) is divided into one layer every 2km, thereby obtaining each atmospheric layer.

[0063] Based on the two stratification methods mentioned above, this application can further subdivide each stratum into 10 layers. That is, when each 1km is a stratum, it can be further subdivided into an atmospheric stratum of 100m. When each 2km is a stratum, it can be further subdivided into an atmospheric stratum of 200m.

[0064] Step S12: Obtain the observation lines of satellites on different bands at the same time to the target under test, and perform light tracing on each observation line to obtain the corresponding light tracing trajectory.

[0065] In this embodiment of the invention, the observation lines of satellites on different bands at the same time to the target under test are obtained, and the light traces of each observation line are tracked to obtain the light tracing trajectories corresponding to each observation line.

[0066] In the process of tracing the light trail for each observation line, the intersection points between each observation line and each atmospheric layer after atmospheric refraction are first determined. Each atmospheric layer is obtained by dividing the high-density atmospheric layer. Then, based on the latitude and longitude of each intersection point and the height of the atmospheric layer in which each intersection point is located, the coordinates of each intersection point are determined. Based on the coordinates of each intersection point, the intersection points are connected and smoothed to obtain the light tracing trajectory. The light tracing trajectory is the actual refracted light rays from the satellite to the target object formed after atmospheric refraction of the observation line.

[0067] by Figure 2 The diagram illustrating atmospheric refraction during liminal propagation of starlight is used as an example. When starlight from a low-density atmosphere enters a high-density atmosphere, the air density in the high-density atmosphere is gradient-distributed. Therefore, the incident starlight rays first bend towards the Earth's center, then deviate from the Earth's center and emerge outwards from the high-density atmosphere until they enter the target's line of sight. This mode of light propagation is generally called liminal propagation of starlight. It can be observed that the incident starlight rays undergo refraction at each atmospheric layer within the high-density atmosphere. The i-th atmospheric layer is represented by the starlight incident rays in the low-density atmosphere, which are equivalent to the line of sight. The red trajectory line is equivalent to the ray tracing trajectory obtained after tracing the line of sight.

[0068] Specifically, for each observation line of sight, by ray tracing on the observation line of sight, intersection points between the observation line of sight after atmospheric refraction and each atmospheric layer are determined, and the longitude and latitude of each intersection point are determined in turn according to the propagation direction of the observation line of sight. In the process of determining the longitude and latitude of each intersection point in turn according to the propagation direction of the observation line of sight, the central angle of the current intersection point is determined based on the atmospheric layer where the current intersection point is located and the zenith angle of the current intersection point; and the longitude and latitude of the current intersection point are determined according to the central angle of the current intersection point. Then, the coordinates of each intersection point are determined based on the longitude and latitude of each intersection point and the layer height of the atmospheric layer where each intersection point is located, and each intersection point is connected and smoothed based on the coordinates of each intersection point to obtain a ray tracing trajectory.

[0069] In the process of determining the central angle of the current intersection point based on the atmospheric layer where the current intersection point is located and the zenith angle of the current intersection point, it is first determined whether the atmospheric layer where the current intersection point is located is the atmospheric layer farthest from the earth's surface. Wherein, as shown in the formula (1), the zenith angle is the angle between the observation line of sight and the geocentric vector at the intersection point. Figure 3

[0070] If the atmospheric layer where the current intersection point is located is the atmospheric layer farthest from the earth's surface, the central angle of the current intersection point is determined based on the first angle and the zenith angle of the current intersection point; wherein the first angle is the angle between the current line of sight direction and the reverse direction of the geocentric vector at the current intersection point; and the current line of sight direction is the line of sight direction after the observation line of sight is refracted through the atmospheric layer where the previous intersection point is located. Specifically, the central angle of the current intersection point is: wherein represents the zenith angle of the current intersection point, and represents the first angle.

[0071] If the atmospheric layer where the current intersection point is located is not the atmospheric layer farthest from the earth's surface, it is further determined whether the zenith angle of the current intersection point is a right angle; wherein if the zenith angle of the current intersection point is a right angle, it represents that the current intersection point is a tangent point, and if the zenith angle of the current intersection point is not a right angle, it represents that the current intersection point is a non-tangent point.

[0072] If the zenith angle of the current intersection point is not a right angle, the central angle of the current intersection point is determined based on the layer height of the atmospheric layer where the current intersection point is located, the zenith angle of the current intersection point and the atmospheric refraction index. Specifically, the central angle of the current intersection point is: wherein asin() is arcsin(), which represents the inverse sine function, represents the zenith angle of the current intersection point, represents the atmospheric refraction index of the current intersection point, represents the Bouquer quantity calculated based on the atmospheric refraction index of the current intersection point, and H2 represents the layer height of the atmospheric layer where the current intersection point is located.

[0073] ​​If the zenith angle of the current intersection point is a right angle, a geocentric angle of the current intersection point is determined based on a tangent point height and a layer height of an atmospheric layer in which the current intersection point is located; the tangent point height is a height closest to the earth's surface after the observation line is refracted by the atmosphere, that is, the height closest to the earth's surface of the actual refracted light formed after the observation line is refracted by the atmosphere. Specifically, the geocentric angle of the current intersection point is: , represents the tangent point height.

[0074] In the process of determining the latitude of the current intersection point according to the geocentric angle of the current intersection point, a latitude direction angle of the current intersection point is determined based on the geocentric angle of the current intersection point and the angle between the current line of sight direction and the latitude line, and it is judged whether the latitude direction angle of the current intersection point is equal to zero. If the latitude direction angle of the current intersection point is equal to zero, the latitude of the previous intersection point is determined as the latitude of the current intersection point. If the latitude direction angle of the current intersection point is not equal to zero, the latitude update mode is determined based on the angle between the current line of sight direction and the due east direction; the latitude update mode includes a latitude increment mode and a latitude decrement mode; then the latitude of the previous intersection point is updated using the latitude update mode and based on the latitude direction angle of the current intersection point, so as to determine the latitude of the current intersection point based on the updated latitude.

[0075] For the determination of the latitude direction angle of the current intersection point, firstly, it is judged whether the geocentric angle of the current intersection point is equal to zero. If the geocentric angle of the current intersection point is equal to zero, the latitude direction angle of the current intersection point is determined as zero. If the geocentric angle of the current intersection point is not equal to zero, the angle between the current line of sight direction and the latitude line is determined. If the angle between the current line of sight direction and the latitude line is equal to 90 degrees, it indicates that the current observation is along the meridian, and the geocentric angle of the current intersection point is determined as the latitude direction angle of the current intersection point. If the angle between the current line of sight direction and the latitude line is equal to zero degree, it indicates that the current observation is along the latitude line, and the latitude direction angle of the current intersection point is determined as zero. If the angle between the current line of sight direction and the latitude line is neither equal to 90 degrees nor equal to zero degree, it indicates that the current observation is neither along the meridian nor along the latitude line, and the latitude direction angle of the current intersection point is determined based on the geocentric angle of the current intersection point and the angle between the current line of sight direction and the latitude line; the calculation formula of the latitude direction angle of the current intersection point is: , represents the angle between the current line of sight direction and the latitude line.

[0076] After the latitude direction angle of the current intersection point is determined, if the latitude direction angle of the current intersection point is not equal to zero, the angle between the current line of sight direction and the due east direction is determined. If the angle between the current line of sight direction and the due east direction is between 0-180 degrees, the latitude update mode is determined as the latitude increment mode. If the angle between the current line of sight direction and the due east direction is between -180-0 degrees, the latitude update mode is determined as the latitude decrement mode.

[0077] If the latitude updating manner is the latitude increment manner, the latitude of the previous intersection point is incremented based on the latitudinal angle of the current intersection point to obtain an updated latitude, i.e., the updated latitude = the latitude of the previous intersection point + the latitudinal angle of the current intersection point, and then it is judged whether the updated latitude is greater than 90 degrees. If the updated latitude is not greater than 90 degrees, the updated latitude is determined as the latitude of the current intersection point. If the updated latitude is greater than 90 degrees, the latitude of the current intersection point is obtained by subtracting the updated latitude from 180 degrees, i.e., the latitude of the current intersection point = 180 degrees - the updated latitude.

[0078] If the latitude updating manner is the latitude decrement manner, the latitude of the previous intersection point is decremented based on the latitudinal angle of the current intersection point to obtain an updated latitude, i.e., the updated latitude = the latitude of the previous intersection point - the latitudinal angle of the current intersection point, and then it is judged whether the updated latitude is less than -90 degrees. If the updated latitude is not less than -90 degrees, the updated latitude is determined as the latitude of the current intersection point. If the updated latitude is less than -90 degrees, the latitude of the current intersection point is obtained by subtracting the updated latitude from -180 degrees, i.e., the latitude of the current intersection point = -180 degrees - the updated latitude.

[0079] In the process of determining the longitude of the current intersection point according to the central angle of the current intersection point, the longitudinal angle of the current intersection point is determined based on the central angle of the current intersection point, the angle between the current line-of-sight direction and the latitude line, and the latitude of the current intersection point, and then it is judged whether the longitudinal angle of the current intersection point is equal to zero. If the longitudinal angle of the current intersection point is equal to zero, the longitude of the previous intersection point is determined as the longitude of the current intersection point. If the longitudinal angle of the current intersection point is not equal to zero, the longitude updating manner is determined based on the angle between the current line-of-sight direction and the positive east direction; wherein the longitude updating manner includes a longitude increment manner and a longitude decrement manner; and then the longitude of the previous intersection point is updated by using the longitude updating manner and based on the longitudinal angle of the current intersection point, so as to determine the longitude of the current intersection point based on the updated longitude.

[0080] For the determination of the longitudinal angle of the current intersection point, firstly it is judged whether the central angle of the current intersection point is equal to zero. If the central angle of the current intersection point is equal to zero, the longitudinal angle of the current intersection point is determined as zero. If the central angle of the current intersection point is not equal to zero, the angle between the current line-of-sight direction and the latitude line is determined. If the angle between the current line-of-sight direction and the latitude line is equal to 90 degrees, it indicates that the current observation is along the meridian, and the longitudinal angle of the current intersection point is determined as zero. If the angle between the current line-of-sight direction and the latitude line is not equal to 90 degrees, it indicates that the current observation is not along the meridian, and at this time the longitudinal angle of the current intersection point is determined based on the central angle of the current intersection point, the angle between the current line-of-sight direction and the latitude line, and the latitude of the current intersection point, i.e., the calculation formula of the longitudinal angle of the current intersection point is: , wherein φ represents the latitude of the current intersection point.

[0081] After the determination of the longitudinal angle of the current intersection point, if the longitudinal angle of the current intersection point is not equal to zero, the angle between the current line-of-sight direction and the due east direction is determined. If the angle between the current line-of-sight direction and the due east direction is between -90 and 90 degrees, the longitude updating mode is determined as the longitude increment mode. If the angle between the current line-of-sight direction and the due east direction is between -180 and -90 degrees or between 90 and 180 degrees, the longitude updating mode is determined as the longitude decrement mode.

[0082] If the longitude updating mode is the longitude increment mode, the longitude of the previous intersection point is incremented based on the longitudinal angle of the current intersection point to obtain an updated longitude, i.e., the updated longitude = the longitude of the previous intersection point + the longitudinal angle of the current intersection point, and then it is determined whether the updated longitude is greater than 180 degrees. If the updated longitude is not greater than 180 degrees, the updated longitude is determined as the longitude of the current intersection point. If the updated longitude is greater than 180 degrees, the longitude of the current intersection point is converted to the west longitude by subtracting 360 degrees from the updated longitude, i.e., the longitude of the current intersection point = the updated longitude - 360 degrees.

[0083] If the longitude updating mode is the longitude decrement mode, the longitude of the previous intersection point is decremented based on the longitudinal angle of the current intersection point to obtain an updated longitude, i.e., the updated longitude = the longitude of the previous intersection point - the longitudinal angle of the current intersection point, and then it is determined whether the updated longitude is less than -180 degrees. If the updated longitude is not less than -180 degrees, the updated longitude is determined as the longitude of the current intersection point. If the updated longitude is less than -180 degrees, the longitude of the current intersection point is converted to the east longitude by adding 360 degrees to the updated longitude, i.e., the longitude of the current intersection point = the updated longitude + 360 degrees.

[0084] In addition, after the determination of the longitudinal angle of the current intersection point, the current longitudinal angle sum is incremented based on the longitudinal angle of the current intersection point to obtain a new current longitudinal angle sum; wherein the current longitudinal angle sum is zero at the beginning.

[0085] Moreover, since the earth is an ellipsoid model, the earth radius at different positions is different. Since the distance from the current intersection point to the center of the earth, i.e., the center-to-earth distance, is equal to the layer height of the atmospheric layer where the current intersection point is located plus the earth radius corresponding to the current intersection point, the earth radius corresponding to the current intersection point can be determined according to the latitude of the current intersection point, i.e., the calculation formula of the earth radius corresponding to the current intersection point is: .

[0086] After the longitude and latitude of the current intersection point is determined, the coordinates of each intersection point are determined based on the longitude and latitude of each intersection point and the layer height of the atmospheric layer where each intersection point is located, and each intersection point is connected based on the coordinates of each intersection point to obtain an initial tracking trajectory. Then the initial tracking trajectory is smoothed to solve the problem of unevenness of the trajectory caused by unevenness of the atmospheric parameters, thereby obtaining a smoothed light ray tracking trajectory. The trajectory smoothing adopts a high-order polynomial fitting method:

[0087] ;

[0088] represents a fitting coefficient; n represents a fitting order, generally selected as 5 orders; represents a polynomial fitting function, and x represents the coordinates of the intersection point.

[0089] Step S13, determining a target grid through by each light ray tracking trajectory from a preset atmospheric grid model, and determining an extinction coefficient of each target grid.

[0090] When the measured target and the satellite are located in a high-density atmospheric layer and a low-density atmospheric layer respectively, the infrared radiation emitted by the measured target and transmitted to the satellite can be divided into two stages. Stage one is the transmission of infrared radiation in the high-density atmospheric layer, which is subject to atmospheric attenuation. Stage two is the transmission of infrared radiation in the low-density atmospheric layer, which is not subject to energy attenuation.

[0091] Stage one: According to the Beer-Lambert law, the transmission of infrared radiation in the atmosphere will be subject to atmospheric attenuation. This attenuation is caused by absorption and scattering of the atmosphere, and is related to the distance of radiation transmission and the wavelength. Assuming that the radiance of the infrared radiation emitted by the measured target at point O is M, then after atmospheric attenuation, the radiance of the infrared radiation at point P on the demarcation line is , wherein, under the condition of homogeneous atmosphere, ; is the atmospheric extinction coefficient, and d is the distance of the transmission of infrared radiation from the measured target to the demarcation line. The demarcation line is used to distinguish the high-density atmospheric layer and the low-density atmospheric layer, that is, the demarcation line is the boundary line at the preset height of the high-density atmospheric layer from the earth's surface. At this time, the distance from the demarcation line to the earth's surface is the preset height.

[0092] Stage two: The transmission of infrared radiation in the low-density atmospheric layer. Since the satellite is far away from the measured target, the measured target can be regarded as a point source. Therefore, the radiation intensity I received by the camera on the satellite is:

[0093] ;

[0094] wherein R is the distance from the satellite to the demarcation line; is the geometric factor of radiation, which reflects the correction of the radiation direction. This is the energy conversion factor received by the camera, also known as camera sensitivity. It can be observed that, given the atmospheric extinction coefficient... In the case of infrared radiation, if the distance d from the target to the boundary line is calculated by the radiation intensity I, then the height of the target above the Earth's surface is the height of the high-density atmosphere (i.e., the preset height) minus the distance d from the target to the boundary line.

[0095] However, considering that atmospheric conditions are not homogeneous but rather varied in the actual atmospheric environment, the atmospheric extinction coefficient is not constant. Therefore, this application divides the high-density atmosphere into several grids according to latitude, longitude and altitude, and calculates the extinction coefficient of several grids based on the pre-published global aerosol optical depth (AOD) and the height of each grid from the Earth's surface. Then, based on several grids and their extinction coefficients, a pre-defined atmospheric gridded model is constructed.

[0096] It should be noted that this application assumes that the atmospheric composition is uniform in each grid, therefore, the extinction coefficient of each grid can be approximated as constant. Furthermore, the previously disclosed global aerosol optical thickness is distributed at spatial intervals of approximately 1 degree * 1 degree (surface latitude and longitude) and is updated approximately monthly.

[0097] There are two methods for calculating the extinction coefficient of several grids: Method 1 is to define a Logistic model for the vertical distribution of atmospheric extinction coefficient and calculate the parameters in the Logistic model to determine the extinction coefficient of several grids; Method 2 is to define and solve a negative exponential model for the vertical distribution of atmospheric extinction coefficient to determine the extinction coefficient of several grids.

[0098] Specifically, the mathematical expression for the Logistic model of the vertical distribution of atmospheric extinction coefficient in Method 1 is as follows:

[0099] ;

[0100] In the formula: z represents the height of a certain location in the high-density atmosphere above the Earth's surface. This represents the extinction coefficient at a height z above the Earth's surface; , , These are the parameters of the Logistic model for the vertical distribution of atmospheric extinction coefficient.

[0101] Using AOD, the height of the high-density atmosphere, and the extinction coefficient as constraints, the parameters of the logistic model for the vertical distribution of atmospheric extinction coefficient are calculated as follows:

[0102] The value of the AOD is recorded as , which is the integral of the atmospheric extinction coefficient in the vertical direction, i.e. ; the top of the high-density atmospheric layer , i.e. the preset height, is the height at which the turbulent characteristic discontinuous interface is located, corresponding to the maximum curvature point of the Logistic curve, further identifying the height of the high-density atmospheric layer, recorded as H, and thus .

[0103] Since the atmospheric extinction coefficient and the atmospheric visibility satisfy Koschmieder's formula, the atmospheric extinction coefficient near the ground surface (i.e. the extinction coefficient at a height of 0 from the earth's surface) obtained by inversion of the formula is , and at this time .

[0104] Combining the above several formulas, the model parameters , , can be solved, and thus the atmospheric extinction coefficient vertical distribution Logistic model is obtained, and according to the atmospheric extinction coefficient vertical distribution Logistic model and the height of each grid from the earth's surface, the extinction coefficients of a plurality of grids can be determined.

[0105] In mode two, the extinction coefficient is determined by the number of aerosol particles in the atmosphere and the extinction cross section, and the extinction cross section is related to the particle type, size and wavelength. If the aerosol composition and spectral distribution do not change with the height, the extinction cross section does not change with the height z from the earth's surface, and thus the following formula is obtained:

[0106] ;

[0107] In the formula: represents the extinction coefficient at a height of 0 from the earth's surface, represents the extinction coefficient at a height of z from the earth's surface; the aerosol concentration at a height of 0 from the earth's surface is recorded as N(0), and the aerosol concentration at a height of z from the earth's surface is recorded as N(z).

[0108] It is assumed that the aerosol density decreases exponentially with the height under the action of the earth's gravity, i.e. ; wherein represents the atmospheric altitude, with a unit of km, which can be approximately replaced by the height of the boundary line (i.e. the preset height).

[0109] Combining the above formula, the atmospheric extinction coefficient vertical distribution exponential model can be solved, and according to the atmospheric extinction coefficient vertical distribution exponential model and the height of each grid from the earth's surface, the extinction coefficients of a plurality of grids can be determined.

[0110] After the preset atmospheric gridding model is constructed, the target grid through by each light ray tracing trajectory needs to be determined from the preset atmospheric gridding model, as shown in the figure, the red line is the light ray tracing trajectory, and the blue line box is the target grid through by the light ray tracing trajectory in the preset atmospheric gridding model, and the extinction coefficient of each target grid needs to be determined from the preset atmospheric gridding model. Figure 4

[0111] Step S14, a preset radiation intensity calculation formula is used to construct a target function of a radiation intensity ratio with respect to a target height from the earth's surface based on the extinction coefficient of each target grid through by the light ray tracing trajectory.

[0112] In the embodiment of the present application, based on the preset radiation intensity calculation formula, a ratio formula of two radiation intensities of infrared radiation on different wave bands at the same time is determined; wherein the preset radiation intensity calculation formula is an exponential calculation formula of radiation intensity with respect to the distance of infrared radiation from the measured target to the demarcation line and the extinction coefficient; the demarcation line is used to distinguish the high-density atmosphere layer and the low-density atmosphere layer. The ratio formula is used to construct a target function of a radiation intensity ratio with respect to a target height from the earth's surface based on the extinction coefficient of each target grid through by the light ray tracing trajectory and the distance of each light ray tracing trajectory in each target grid; wherein the distance of each light ray tracing trajectory in each target grid is determined based on the height of each target grid from the earth's surface.

[0113] In the embodiment of the present application, it is considered that under the condition of homogeneous atmosphere, the preset radiation intensity calculation formula is , it is assumed that the radiation intensity at the height z from the earth's surface on the wave band i at the same time is , the radiation intensity at the height z from the earth's surface on the wave band j at the same time is , and the ratio formula of the two radiation intensities on the wave band i and the wave band j at the same time is . Wherein, and respectively represent the emittance of infrared radiation on the wave band i and the wave band j at the measured target, represents the distance of infrared radiation from the measured target to the height z from the earth's surface, and respectively represent the extinction coefficient at the height z from the earth's surface on the wave band i and the wave band j.

[0114] Since the ratio formula is a transcendental equation, it is difficult to solve the analytical solution of the distance , and it can be seen that the radiation intensity ratio and the distance ​The exponential function relationship is presented. However, in practical applications, the extinction coefficient of the atmosphere is constantly changing. In order to solve this problem, the present application introduces a preset atmospheric grid model, and regards the extinction coefficient of each grid in the preset atmospheric grid model as the same. Further, the present application determines the target grid through which each light ray tracking trajectory passes from the preset atmospheric grid model, and determines the extinction coefficient of each target grid. With the transmission and accumulation of the light ray tracking trajectory, the radiation intensity on the complete trajectory can be obtained by cascading the band ratio of each target grid, at this time, based on the extinction coefficient of the target grid through which each light ray tracking trajectory passes and the distance of each light ray tracking trajectory in each target grid, the ratio formula can be converted to:

[0115] ;

[0116] Wherein, represents the radiation intensity ratio; m represents the total number of target grids through which each light ray tracking trajectory passes; represents the height of the kth target grid from the earth's surface; represents the distance of each light ray tracking trajectory in the kth target grid, and the distance of each light ray tracking trajectory in each target grid can be determined based on the height of each target grid from the earth's surface, so the above ratio formula has only one variable, that is , that is, the above ratio formula can be regarded as a discrete function about , by fitting the ratio formula, a continuous function about the target height from the earth's surface can be obtained, at this time, the continuous function is the target function of the radiation intensity ratio about the target height from the earth's surface.

[0117] Step S15, determining the target height of the measured target from the earth's surface based on the target function and the target radiation intensity ratio.

[0118] Step S16, determining the position of the measured target according to the trajectory point in each light ray tracking trajectory matched with the target height, and determining the line-of-sight vector corrected by atmospheric refraction based on the position of the measured target and the position of the satellite.

[0119] In the embodiment of the present application, the target radiation intensity ratio is substituted into the target function of the radiation intensity ratio about the target height from the earth's surface to determine the target height of the measured target from the earth's surface, then the trajectory point matched with the target height is determined from each light ray tracking trajectory to obtain the position of the measured target, and finally the line-of-sight vector corrected by atmospheric refraction is determined based on the position of the measured target and the position of the satellite.

[0120] For determining the trajectory point matching the target height from each light ray tracking trajectory, specifically comprising: querying the trajectory points in each light ray tracking trajectory based on the target height, and determining whether the trajectory point matching the target height is queried; if not, interpolating the trajectory points in each light ray tracking trajectory based on the target height to obtain the trajectory point matching the target height.

[0121] After the position of the measured target and the position of the satellite are known, the position of the measured target and the position of the satellite are converted into the geocentric inertial coordinate system to obtain corresponding target coordinates and satellite coordinates; the initial line-of-sight vector is obtained by subtracting the satellite coordinates from the target coordinates; and the initial line-of-sight vector is normalized to obtain the line-of-sight vector after atmospheric refraction correction.

[0122] It can be seen that, according to the present application, the atmospheric transmittance of infrared radiation is different at different wave bands, so the radiation intensity obtained at different wave bands is also different, and correspondingly, the target radiation intensity ratio determined based on the radiation intensity at different wave bands is also different; since the target radiation intensity ratio changes with the target height of the measured target from the earth's surface, the present application tracks the light path of the observation line of sight of the satellite to the measured target to obtain the corresponding light ray tracking trajectory, then constructs a target function of the radiation intensity ratio with respect to the height of the target from the earth's surface according to the extinction coefficient of the target grid through which each light ray tracking trajectory passes in the preset atmospheric gridding model and a preset radiation intensity calculation formula, so as to more accurately determine the target height of the measured target from the earth's surface by using the target function and the known target radiation intensity ratio, and finally correct the line-of-sight vector of the satellite to the measured target by using the target height of the measured target from the earth's surface, to realize high-precision atmospheric refraction correction under single-satellite observation conditions.

[0123] Referring to Figure 5 The embodiment of the present application discloses a single-satellite target line-of-sight atmospheric refraction correction system based on multi-spectral ranging, which comprises:

[0124] The radiation intensity ratio determination module 11 is configured to acquire the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the measured target at different wave bands at the same time, and determine the target radiation intensity ratio based on the first radiation intensity and the second radiation intensity.

[0125] The light path tracking module 12 is configured to acquire the observation line of sight of the satellite to the measured target at different wave bands at the same time, and track the light path of each observation line of sight to obtain the corresponding light ray tracking trajectory.

[0126] The extinction coefficient determination module 13 is configured to determine the target grid through which each light ray tracking trajectory passes from the preset atmospheric gridding model, and determine the extinction coefficient of each target grid.

[0127] The target function construction module 14 is configured to construct a target function of the radiation intensity ratio with respect to the height of the target from the earth's surface based on the optical extinction coefficient of each of the light ray tracing trajectories passing through the target grid and the preset radiation intensity calculation formula.

[0128] The target height determination module 15 is configured to determine the target height of the target from the earth's surface based on the target function and the target radiation intensity ratio.

[0129] The atmospheric refraction correction module 16 is configured to determine the position of the target based on the trajectory point matching the target height in each of the light ray tracing trajectories, and determine the atmospheric refraction corrected line-of-sight vector based on the position of the target and the position of the satellite.

[0130] It can be seen that, according to the present application, the atmospheric transmittance of infrared radiation is different at different wave bands, and therefore the radiation intensity obtained at different wave bands is also different. Correspondingly, the target radiation intensity ratio determined based on the radiation intensity at different wave bands is also different. Since the target radiation intensity ratio changes with the target height of the target from the earth's surface, the present application traces the observation line of sight of the satellite to the target to obtain corresponding light ray tracing trajectories, and then constructs a target function of the radiation intensity ratio with respect to the height of the target from the earth's surface based on the optical extinction coefficient of each of the light ray tracing trajectories passing through the target grid and the preset radiation intensity calculation formula. Thus, the target height of the target from the earth's surface is more accurately determined by using the target function and the known target radiation intensity ratio. Finally, the line-of-sight vector of the satellite to the target is corrected by using the target height of the target from the earth's surface, so as to realize high-precision atmospheric refraction correction under single-satellite observation conditions.

[0131] In some embodiments, the target and the satellite are located in a high-density atmospheric layer and a low-density atmospheric layer, respectively. The high-density atmospheric layer is a region in the atmospheric layer within a preset height from the earth's surface. The low-density atmospheric layer is a region in the atmospheric layer outside the preset height from the earth's surface.

[0132] In some embodiments, the light ray tracing module 12 comprises:

[0133] The intersection determination unit is configured to determine the intersection points of each of the observation lines of sight after atmospheric refraction and each of the atmospheric layers. Each of the atmospheric layers is obtained by layering the high-density atmospheric layer.

[0134] The coordinate determination unit is configured to determine the coordinates of each of the intersection points based on the longitude and latitude of each of the intersection points and the layer height of the corresponding atmospheric layer.

[0135] The trajectory acquisition unit is configured to connect and smooth the intersection points based on the coordinates of the intersection points to obtain corresponding ray tracing trajectories.

[0136] In some embodiments, the single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging further comprises:

[0137] The grid division unit is configured to divide the high-density atmosphere layer into a plurality of grids according to latitude, longitude, and height.

[0138] The extinction coefficient calculation unit is configured to calculate the extinction coefficients of the plurality of grids based on the pre-disclosed global aerosol optical thickness and the height of each grid from the earth's surface.

[0139] The model construction unit is configured to construct the preset atmospheric grid model based on the plurality of grids and the extinction coefficients of the plurality of grids.

[0140] In some embodiments, the target function construction module 14 comprises:

[0141] The ratio formula determination unit is configured to determine a ratio formula of two radiation intensities of the infrared radiation at different wave bands at the same time based on a preset radiation intensity calculation formula; the preset radiation intensity calculation formula is an exponential calculation formula of radiation intensity with respect to the distance of the infrared radiation from the measured target to a demarcation line and the extinction coefficient; the demarcation line is used to distinguish the high-density atmosphere layer and the low-density atmosphere layer.

[0142] The function construction unit is configured to construct a target function of the radiation intensity ratio with respect to the height of the target from the earth's surface by using the ratio formula and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes and the distance of each ray tracing trajectory in each target grid; the distance of each ray tracing trajectory in each target grid is determined based on the height of each target grid from the earth's surface.

[0143] In some embodiments, the single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging further comprises:

[0144] The trajectory point query unit is configured to query a trajectory point in each ray tracing trajectory based on the target height and determine whether a trajectory point matching the target height is queried.

[0145] The trajectory point interpolation unit is configured to perform trajectory point interpolation on each ray tracing trajectory based on the target height to obtain a trajectory point matching the target height if no trajectory point is queried.

[0146] In some embodiments, the atmospheric refraction correction module 16 comprises:

[0147] a coordinate system conversion unit, configured to convert the position of the target and the position of the satellite into an earth-centered inertial coordinate system to obtain corresponding target coordinates and satellite coordinates;

[0148] an initial vector obtaining unit, configured to subtract the satellite coordinates from the target coordinates to obtain an initial line-of-sight vector;

[0149] a normalization unit, configured to normalize the initial line-of-sight vector to obtain an atmospheric refraction corrected line-of-sight vector.

[0150] Finally, each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between each embodiment can be referred to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0151] It should also be noted that the relational terms herein, such as first and second, are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or equipment including the element.

[0152] The above describes the technical solutions provided by the present application in detail. The principles and implementation manners of the present application are described by specific examples. The above description of the embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed; in summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for single-satellite target line-of-sight atmospheric refraction correction based on multi-spectrum ranging, characterized in that, The method comprises the following steps: acquiring first and second radiation intensities of infrared radiation emitted by a target at different wave bands at the same time, and determining a target radiation intensity ratio based on the first and second radiation intensities; acquiring observation lines of sight of a satellite to the target at different wave bands at the same time, and performing ray tracing on each observation line of sight to obtain a corresponding ray tracing trajectory; determining a target grid through which each ray tracing trajectory passes from a preset atmospheric gridding model, and determining an extinction coefficient of each target grid; constructing a target function of a radiation intensity ratio with respect to a target height from the earth's surface by using a preset radiation intensity calculation formula and based on the extinction coefficient of each target grid through which each ray tracing trajectory passes; determining a target height of the target from the earth's surface based on the target function and the target radiation intensity ratio; determining a position of the target based on a trajectory point in each ray tracing trajectory that matches the target height, and determining an atmospheric refraction corrected line of sight vector based on the position of the target and a position of the satellite; wherein the target and the satellite are located in a high-density atmospheric layer and a low-density atmospheric layer respectively; the high-density atmospheric layer is a region in the atmospheric layer within a preset height from the earth's surface; and the low-density atmospheric layer is a region in the atmospheric layer outside the preset height from the earth's surface; wherein the step of constructing the target function of the radiation intensity ratio with respect to the target height from the earth's surface by using the preset radiation intensity calculation formula and based on the extinction coefficient of each target grid through which each ray tracing trajectory passes comprises: determining a ratio formula of two radiation intensities of the infrared radiation at different wave bands at the same time based on a preset radiation intensity calculation formula; the preset radiation intensity calculation formula is an exponential calculation formula of radiation intensity with respect to a distance of the infrared radiation from the target to a demarcation line and an extinction coefficient; and the demarcation line is used to distinguish the high-density atmospheric layer and the low-density atmospheric layer; constructing the target function of the radiation intensity ratio with respect to the target height from the earth's surface by using the ratio formula and based on the extinction coefficient of each target grid through which each ray tracing trajectory passes, and a distance of each ray tracing trajectory in each target grid; wherein the distance of each ray tracing trajectory in each target grid is determined based on a height of each target grid from the earth's surface.

2. The single-star target line-of-sight atmospheric refraction correction method based on multi-band ranging according to claim 1, characterized in that, The step of performing ray tracing on each observation line of sight to obtain a corresponding ray tracing trajectory comprises: determining intersection points between each observation line of sight after atmospheric refraction and each atmospheric layering; each atmospheric layering is obtained by layering the high-density atmospheric layer; determining coordinates of each intersection point based on longitude and latitude of each intersection point and a layer height of a corresponding atmospheric layering; connecting and smoothing each intersection point based on the coordinates of each intersection point to obtain a corresponding ray tracing trajectory.

3. The single-star target line-of-sight atmospheric refraction correction method based on multi-band ranging according to claim 1, characterized in that, The construction process of the preset atmospheric gridding model comprises: dividing the high-density atmospheric layer into a plurality of grids according to longitude, latitude and height; Calculate the extinction coefficients of the grids based on the pre-disclosed global aerosol optical thickness and the height of each grid from the earth surface; Construct the preset atmospheric gridding model based on the grids and the extinction coefficients of the grids.

4. The single-star target line-of-sight atmospheric refraction correction method based on multi-band ranging according to claim 1, characterized in that, Before determining the position of the measured target according to the trajectory point in each light ray tracing trajectory that matches the target height, the method further includes: Query the trajectory points in each light ray tracing trajectory based on the target height, and determine whether a trajectory point that matches the target height is queried; If not, perform trajectory point interpolation on each light ray tracing trajectory based on the target height to obtain a trajectory point that matches the target height.

5. The single-star target line-of-sight atmospheric refraction correction method based on multi-band ranging according to any one of claims 1 to 4, characterized in that, The method further includes: Convert the position of the measured target and the position of the satellite into the earth-centered inertial coordinate system to obtain corresponding target coordinates and satellite coordinates; Subtract the satellite coordinates from the target coordinates to obtain an initial line-of-sight vector; Normalize the initial line-of-sight vector to obtain an atmospheric refraction corrected line-of-sight vector.

6. A multi-spectrum ranging-based single-satellite target line-of-sight atmospheric refraction correction system, characterized in that, The method further includes: The radiation intensity ratio determination module is configured to acquire first radiation intensity and second radiation intensity of infrared radiation emitted by a measured target at different wave bands at the same time, and determine a target radiation intensity ratio based on the first radiation intensity and the second radiation intensity; The light trace tracking module is configured to acquire observation lines of sight of a satellite to the measured target at different wave bands at the same time, and perform light trace tracking on each observation line of sight to obtain a corresponding light ray tracing trajectory; The extinction coefficient determination module is configured to determine a target grid through by each light ray tracing trajectory from a preset atmospheric gridding model, and determine an extinction coefficient of each target grid; The target function construction module is configured to construct a target function of the radiation intensity ratio with respect to the height of the target from the earth surface by using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through by each light ray tracing trajectory; The target height determination module is configured to determine the target height of the measured target from the earth surface based on the target function and the target radiation intensity ratio; The atmospheric refraction correction module is configured to determine the position of the measured target according to a trajectory point in each light ray tracing trajectory that matches the target height, and determine an atmospheric refraction corrected line-of-sight vector based on the position of the measured target and the position of the satellite. The measured target and the satellite are located in a high-density atmospheric layer and a low-density atmospheric layer, respectively; the high-density atmospheric layer is a region in the atmospheric layer within a preset height from the earth surface; and the low-density atmospheric layer is a region in the atmospheric layer outside the preset height from the earth surface. The target function construction module includes: A ratio formula determination unit is configured to determine a ratio formula of two radiation intensities of the infrared radiation at different wave bands at the same time based on a preset radiation intensity calculation formula. The preset radiation intensity calculation formula is an exponential calculation formula of the radiation intensity with respect to a distance of the infrared radiation from the measured target to a demarcation line and an extinction coefficient. The demarcation line is used to distinguish the high-density atmosphere layer and the low-density atmosphere layer. A function construction unit is configured to construct a target function of radiation intensity ratio with respect to a height of a target from the earth surface by using the ratio formula and based on an extinction coefficient of a target grid through which each of the ray tracing trajectories passes and a distance of each of the ray tracing trajectories in each of the target grids. The distance of each of the ray tracing trajectories in each of the target grids is determined based on a height of each of the target grids from the earth surface.

7. The multi-band ranging based single star target line-of-sight atmospheric refraction correction system according to claim 6, wherein, Further comprising: A trajectory point query unit is configured to query a trajectory point in each of the ray tracing trajectories based on the target height and determine whether a trajectory point matching the target height is queried. A trajectory point interpolation unit is configured to perform trajectory point interpolation on each of the ray tracing trajectories based on the target height to obtain a trajectory point matching the target height if no trajectory point matching the target height is queried.

8. The multi-band ranging based single star target line-of-sight atmospheric refraction correction system according to claim 6 or 7, characterized in that, The atmospheric refraction correction module comprises: A coordinate system conversion unit is configured to convert a position of the measured target and a position of the satellite into an earth-centered inertial coordinate system to obtain corresponding target coordinates and satellite coordinates. An initial vector acquisition unit is configured to obtain an initial line-of-sight vector by subtracting the satellite coordinates from the target coordinates. A normalization unit is configured to normalize the initial line-of-sight vector to obtain an atmospheric refraction corrected line-of-sight vector.

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