Single-satellite target sight atmospheric refraction correction method and system based on multi-spectral range finding

Abstract

The invention discloses a single-satellite target sight atmospheric refraction correction method and system based on multi-spectral range finding, and relates to the field of atmospheric refraction processing, and the method comprises the steps: determining a target radiation intensity ratio based on two radiation intensities on different wavebands at the same moment; obtaining observation sight lines of the satellite on the measured target on different wave bands at the same moment, and carrying out light trace tracking to obtain a light ray tracking trajectory; determining a target grid through which each ray tracing trajectory passes from the atmosphere gridding model, determining an extinction coefficient of each target grid, and constructing a target function of a radiation intensity ratio with respect to the height of the target from the ground in combination with a radiation intensity calculation formula; determining a target height from the measured target to the ground based on a target function and a target radiation intensity ratio, determining the position of the measured target according to a track point matched with the target height in each light ray tracing track, and determining a sight line vector after atmospheric refraction correction by combining the position of a satellite, therefore, high-precision atmospheric refraction correction under a single-star observation condition is realized.

Description

Technical Field

[0001] This invention relates to the field of atmospheric refraction processing, and in particular to a method and system for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging. Background Technology

[0002] Atmospheric refraction is a common phenomenon, its magnitude depending on the direction of light incidence and the density distribution of the atmosphere. When a satellite observes a target located within the atmosphere, atmospheric refraction can cause deviations in the line-of-sight determination process, resulting in false targets. Therefore, correcting for atmospheric refraction in the observation line of sight has become a key focus. Traditional atmospheric refraction correction methods primarily rely on knowing the target's spatial location and then applying atmospheric refraction correction based on that location. However, under single-satellite observation conditions, accurately obtaining the target's spatial location leads to low accuracy in correcting the observation line based on atmospheric refraction. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method and system for atmospheric refraction correction of a single-star target's line of sight based on multi-spectral ranging, which can more accurately determine the position of the measured target and achieve high-precision atmospheric refraction correction under single-star observation conditions. The specific scheme is as follows:

[0004] In a first aspect, this application provides a method for correcting atmospheric refraction along the line of sight of a single-star target based on multi-spectral ranging, including:

[0005] The first and second radiation intensities of infrared radiation emitted by the target at different wavelengths at the same time are obtained, and the target radiation intensity ratio is determined based on the first and second radiation intensities.

[0006] 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 corresponding light tracing trajectory.

[0007] The target grid through which each ray tracing trajectory passes is determined from the preset atmospheric gridded model, and the extinction coefficient of each target grid is determined;

[0008] Using a pre-defined formula for calculating radiation intensity and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes, a target function of radiation intensity ratio with respect to the height of the target from the Earth's surface is constructed.

[0009] Based on the objective function and the target radiation intensity ratio, the target height of the measured target from the Earth's surface is determined;

[0010] The position of the target is determined based on the trajectory points in each ray tracing trajectory that match the target height, and the atmospheric refraction-corrected line-of-sight vector is determined based on the position of the target and the position of the satellite.

[0011] Optionally, the target being measured and the satellite are located in a high-density atmosphere and a low-density atmosphere, respectively; the high-density atmosphere is the region within the atmosphere at a preset altitude above the Earth's surface; the low-density atmosphere is the region within the atmosphere at a preset altitude above the Earth's surface.

[0012] Optionally, the step of performing ray tracing on each of the observed lines of sight to obtain the corresponding ray tracing trajectory includes:

[0013] Determine the intersection point between each observation line of sight after atmospheric refraction and each atmospheric layer; each atmospheric layer is a layer obtained by dividing the high-density atmospheric layer.

[0014] The coordinates of each intersection point are determined based on the latitude and longitude of each intersection point and the corresponding atmospheric layer height.

[0015] The intersection points are connected and smoothed based on their coordinates to obtain the corresponding ray tracing trajectory.

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

[0017] The high-density atmosphere is divided into several grids according to latitude, longitude, and altitude;

[0018] Based on the pre-published global aerosol optical thickness and the height of each grid from the Earth's surface, the extinction coefficients of the aforementioned grids are calculated.

[0019] Based on the aforementioned grids and their extinction coefficients, the preset atmospheric gridded model is constructed.

[0020] Optionally, the step of constructing a target function of the radiation intensity ratio with respect to the height of the target above the Earth's surface using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid traversed by each ray tracing trajectory includes:

[0021] Based on a preset radiation intensity calculation formula, a formula is used to determine the ratio of two radiation intensities in different bands of infrared radiation at the same time; the preset radiation intensity calculation formula is an exponential formula for calculating radiation intensity with respect to the distance the infrared radiation travels from the target to the boundary line and the extinction coefficient; the boundary line is used to distinguish between the high-density atmosphere and the low-density atmosphere.

[0022] Using the ratio formula, and based on the extinction coefficient of the target grid traversed by each ray tracing trajectory and the distance traveled by each ray tracing trajectory in each target grid, a target function of the radiation intensity ratio with respect to the height of the target above the Earth's surface is constructed; wherein, the distance traveled by each ray tracing trajectory in each target grid is determined based on the height of each target grid above the Earth's surface.

[0023] Optionally, before determining the position of the target based on the trajectory points in each ray tracing trajectory that match the target height, the method further includes:

[0024] Based on the target height, the trajectory points in each ray tracing trajectory are queried, and it is determined whether a trajectory point matching the target height is found.

[0025] If no match is found, trajectory point interpolation is performed on each ray tracing trajectory based on the target height to obtain trajectory points that match the target height.

[0026] Optionally, determining the line-of-sight vector after atmospheric refraction correction based on the position of the target and the position of the satellite includes:

[0027] The positions of the target and the satellite are transformed into a geocentric inertial coordinate system to obtain the corresponding target coordinates and satellite coordinates.

[0028] The initial line-of-sight vector is obtained by subtracting the satellite coordinates from the target coordinates;

[0029] The initial line-of-sight vector is normalized to obtain the line-of-sight vector corrected for atmospheric refraction.

[0030] Secondly, this application provides a single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging, comprising:

[0031] The radiation intensity ratio determination module is used to acquire the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the target at different wavelengths at the same time, and to determine the target radiation intensity ratio based on the first radiation intensity and the second radiation intensity.

[0032] The light tracing module is used to acquire the observation lines of satellites on different bands at the same time to the target under test, and to perform light tracing on each observation line to obtain the corresponding light tracing trajectory;

[0033] The extinction coefficient determination module is used to determine the target grid through which each ray tracing trajectory passes from a preset atmospheric gridded model, and to determine the extinction coefficient of each target grid.

[0034] The objective function construction module is used to construct an objective function of the radiation intensity ratio with respect to the height of the target from the Earth's surface, based on a preset radiation intensity calculation formula and the extinction coefficient of the target grid through which each ray tracing trajectory passes.

[0035] The target height determination module is used 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] The atmospheric refraction correction module is used to determine the position of the target under test based on the trajectory points in each ray tracing trajectory that match the target height, and to determine the line-of-sight vector after atmospheric refraction correction based on the position of the target under test and the position of the satellite.

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

[0038] The trajectory point query unit is used to query the trajectory points in each ray tracing trajectory based on the target height, and determine whether a trajectory point matching the target height is found.

[0039] The trajectory point interpolation unit is used to perform trajectory point interpolation on each ray tracing trajectory based on the target height if no match is found, so as to obtain a trajectory point that matches the target height.

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

[0041] The coordinate system transformation unit is used to transform the position of the measured target and the position of the satellite into the geocentric inertial coordinate system to obtain the corresponding target coordinates and satellite coordinates;

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

[0043] The normalization unit is used to normalize the initial line-of-sight vector to obtain the line-of-sight vector after atmospheric refraction correction.

[0044] In this application, the first and second radiation intensities of infrared radiation emitted by the target at different wavelengths at the same time are obtained, and the target radiation intensity ratio is determined based on the first and second radiation intensities; the observation lines of satellites to the target at different wavelengths at the same time are obtained, and ray tracing is performed on each observation line to obtain the corresponding ray tracing trajectory; the target grid through which each ray tracing trajectory passes is determined from a preset atmospheric gridded model, and the extinction coefficient of each target grid is determined; using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes, a target function of radiation intensity ratio with respect to the height of the target above the Earth's surface is constructed; based on the target function and the target radiation intensity ratio, the target height of the target above the Earth's surface is determined; the position of the target is determined according to the trajectory points in each ray tracing trajectory that match the target height, and the atmospheric refraction corrected line-of-sight vector is determined based on the position of the target and the position of the satellite.

[0045] Therefore, this application utilizes the fact that atmospheric transmittance varies across different infrared radiation bands, resulting in varying radiation intensities across these bands. Consequently, the target radiation intensity ratio determined based on these different bands also varies. Since the target radiation intensity ratio changes with the target's altitude above the Earth's surface, this application employs ray tracing of the satellite's line of sight to obtain the corresponding ray tracing trajectory. Then, based on the extinction coefficient of the target grid passed through by each ray tracing trajectory in the preset atmospheric gridded model, and the preset radiation intensity calculation formula, a target function for the radiation intensity ratio with respect to the target's altitude above the Earth's surface is constructed. By utilizing this target function and the known target radiation intensity ratio, the target altitude above the Earth's surface can be determined more accurately. Finally, the target altitude above the Earth's surface is used to correct the line-of-sight vector from the satellite to the target, achieving high-precision atmospheric refraction correction under single-satellite observation conditions. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0047] Figure 1 This is a flowchart of a single-star target line-of-sight atmospheric refraction correction method based on multi-spectral ranging disclosed in this application;

[0048] Figure 2This is a schematic diagram of atmospheric refraction during starlight transmission at the limb of the object disclosed in this application.

[0049] Figure 3 This is a schematic diagram of a zenith angle disclosed in this application;

[0050] Figure 4 This is a schematic diagram of a target mesh through which a ray tracing trajectory passes, as disclosed in this application.

[0051] Figure 5 This is a schematic diagram of the structure of a single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging disclosed in this application. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Traditional atmospheric refraction correction methods generally rely on knowing the target's spatial position and then applying atmospheric refraction correction based on that position. However, under single-satellite observation conditions, the accuracy of atmospheric refraction correction for the observation line is low due to the difficulty in accurately obtaining the target's spatial position. Therefore, this application provides a single-satellite 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 achieve high-precision atmospheric refraction correction under single-satellite observation conditions.

[0054] See Figure 1 As shown, this embodiment of the invention discloses a method for atmospheric refraction correction of the line of sight of a single-star target based on multi-spectral ranging, including:

[0055] Step S11: Obtain the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the target at different wavelengths at the same time, and determine the target radiation intensity ratio based on the first radiation intensity and the second radiation intensity.

[0056] In this embodiment of the invention, under single satellite observation conditions, the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the target at different 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 the infrared radiation emitted by the target under test in band i is acquired. And obtain the second radiation intensity of the infrared radiation emitted by the target in band j. At this point, the target radiation intensity ratio is... .

[0058] It should be noted that the target being measured and the satellite are located in the high-density atmosphere and the low-density atmosphere, respectively; the high-density atmosphere is the region within the atmosphere at a predetermined altitude above the Earth's surface; the low-density atmosphere is the region within the atmosphere at a predetermined altitude above the Earth's surface.

[0059] This invention takes into account the inverse relationship between atmospheric density and altitude above the Earth's surface; that is, the higher the altitude, the lower the atmospheric density. Lower atmospheric density results in a lower refractive index, and when the refractive index is relatively low, the effect of atmospheric refraction can be approximately ignored. Therefore, to study atmospheric refraction, this application selects a region within a predetermined altitude above the Earth's surface in the atmosphere as the observation area, denoted as the high-density atmosphere. The predetermined altitude can be 80 km. In this case, the high-density atmosphere is the region where atmospheric refraction needs to be considered. Correspondingly, the low-density atmosphere is the region outside the predetermined altitude above the Earth's surface; in this case, the low-density atmosphere is the region where atmospheric refraction does not need to be considered.

[0060] Furthermore, in order to study atmospheric refraction more accurately, this application can also divide the high-density atmospheric layer into layers to obtain each atmospheric layer, and then analyze the refraction process of light transmission by studying the refraction between each atmospheric layer.

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

[0062] According to another specific embodiment, this application divides the high-density atmosphere into two parts with a specified altitude as the boundary, wherein the specified altitude is less than a preset altitude, for example, 50 km. Then, the part of the high-density atmosphere closer to the Earth's surface is uniformly stratified according to a first preset distance, and the other part of the high-density atmosphere farther from the Earth's surface is uniformly stratified according to a second preset distance, thereby obtaining each atmospheric layer. For example, when the first preset distance is 1 km and the second preset distance is 2 km, the part of the high-density atmosphere closer to the Earth's surface (0~50 km) is divided into layers of 1 km each, and the part of the high-density atmosphere farther from the Earth's surface (50~80 km) is divided into layers of 2 km each, 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, ray tracing is performed to determine the intersection points between the observation line and each atmospheric layer after atmospheric refraction. Simultaneously, the latitude and longitude of each intersection point are determined sequentially according to the propagation direction of the observation line. During this process, the geocentric angle of the current intersection point is determined based on the atmospheric layer it belongs to and its zenith angle; the latitude and longitude of the current intersection point are then determined based on this geocentric angle. Finally, the coordinates of each intersection point are determined based on its latitude and longitude and the height of its atmospheric layer. These intersection points are then connected and smoothed to obtain the ray tracing trajectory.

[0069] In determining the geocentric angle of the current intersection point based on its atmospheric layer and zenith angle, the first step is to determine whether the atmospheric layer at the current intersection point is the one farthest from the Earth's surface. For example... Figure 3 As shown, the zenith angle is the angle between the line of sight and the geocentric vector at the intersection point.

[0070] If the atmospheric layer where the current intersection point is located is the layer farthest from the Earth's surface, then the geocentric angle of the current intersection point is determined based on the first included angle and the zenith angle of the current intersection point. The first included angle is the angle between the current line of sight and the opposite direction of the geocentric radius vector at the current intersection point; the current line of sight is the direction of the line of sight after refraction through the atmospheric layers where previous intersection points were located. Specifically, the geocentric angle of the current intersection point is: , This represents the zenith angle at the current intersection point. Indicates the first included angle.

[0071] If the atmospheric layer where the current intersection point is located is not the atmospheric layer farthest from the Earth's surface, then it is further determined whether the zenith angle of the current intersection point is a right angle; if the zenith angle of the current intersection point is a right angle, it indicates 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 indicates 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, then the geocentric angle of the current intersection point is determined based on the layer height of the atmospheric layer in which the current intersection point is located, the zenith angle of the current intersection point, and the atmospheric refractive index. Specifically, the geocentric angle of the current intersection point is: asin() is equivalent to arcsin(), representing the arcsine function. This represents the zenith angle at the current intersection point. This represents the atmospheric refractive index at the current intersection point. H1 represents the Bouquer quantity calculated based on the atmospheric refractive index of the current intersection point, and H2 represents the height of the atmospheric layer to which the current intersection point is located.

[0073] If the zenith angle at the current intersection point is a right angle, then the geocentric angle at the current intersection point is determined based on the tangent height and the height of the atmospheric layer in which the current intersection point is located. The tangent height is the height at which the line of sight is closest to the Earth's surface after atmospheric refraction; that is, the height at which the actual refracted ray formed after atmospheric refraction is closest to the Earth's surface. Specifically, the geocentric angle at the current intersection point is: , This indicates the height of the tangent point.

[0074] In determining the latitude of the current intersection point based on its geocentric angle, the latitudinal angle of the current intersection point is determined based on the geocentric angle and the angle between the current line of sight and the parallel of latitude. It is then checked whether the latitudinal angle of the current intersection point is zero. If the latitudinal angle of the current intersection point is zero, the latitude of the previous intersection point is used as the latitude of the current intersection point. If the latitudinal angle of the current intersection point is not zero, the latitude update method is determined based on the angle between the current line of sight and the due east direction. This latitude update method includes both latitude increment and latitude decrement methods. Then, using the latitude update method and the latitudinal angle of the current intersection point, the latitude of the previous intersection point is updated, and the latitude of the current intersection point is determined based on the updated latitude.

[0075] To determine the latitudinal angle of the current intersection point, first determine if the geocentric angle of the current intersection point is zero. If the geocentric angle of the current intersection point is zero, then the latitudinal angle of the current intersection point is set to zero. If the geocentric angle of the current intersection point is not zero, then determine the angle between the current line of sight and the parallel of latitude. If the angle between the current line of sight and the parallel of latitude is 90 degrees, it indicates that the current observation is along a meridian, and the geocentric angle of the current intersection point is set as the latitudinal angle of the current intersection point. If the angle between the current line of sight and the parallel of latitude is zero degrees, it indicates that the current observation is along a parallel of latitude, and the latitudinal angle of the current intersection point is set to zero. If the angle between the current line of sight and the parallel of latitude is neither 90 degrees nor zero degrees, it indicates that the current observation is neither along a meridian nor a parallel of latitude. In this case, the latitudinal 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 and the parallel of latitude. The formula for calculating the latitudinal angle of the current intersection point is: , This indicates the angle between the current line of sight and the parallel of latitude.

[0076] After determining the latitudinal angle of the current intersection point, if the latitudinal angle is not zero, then determine the angle between the current line of sight and the due east direction. If the angle between the current line of sight and the due east direction is between 0 and 180 degrees, then the latitude update method is determined to be an increasing latitude method. If the angle between the current line of sight and the due east direction is between -180 and 0 degrees, then the latitude update method is determined to be a decreasing latitude method.

[0077] If the latitude update method is latitude increment, the latitude of the previous intersection point is incremented based on the latitudinal angle of the current intersection point to obtain the updated latitude. That is, the updated latitude = the latitude of the previous intersection point + the latitudinal angle of the current intersection point. Then, it is determined whether the updated latitude is greater than 90 degrees. If the updated latitude is not greater than 90 degrees, it is set 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. That is, the latitude of the current intersection point = 180 degrees - the updated latitude.

[0078] If the latitude update method is a latitude decrement method, the latitude of the previous intersection point is decremented based on the latitudinal angle of the current intersection point to obtain the updated latitude. That is, the updated latitude = the latitude of the previous intersection point - the latitudinal angle of the current intersection point. Then, it is determined whether the updated latitude is less than -90 degrees. If the updated latitude is not less than -90 degrees, it is set 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. That is, the latitude of the current intersection point = -180 degrees - the updated latitude.

[0079] In determining the longitude of the current intersection point based on its geocentric angle, the longitude angle of the current intersection point is determined based on its geocentric angle, the angle between the current line of sight and the parallel of latitude, and the latitude of the current intersection point. Then, it is checked whether the longitude angle of the current intersection point is zero. If the longitude angle of the current intersection point is zero, the longitude of the previous intersection point is used as the longitude of the current intersection point. If the longitude angle of the current intersection point is not zero, the longitude update method is determined based on the angle between the current line of sight and the due east direction. This longitude update method includes both increasing and decreasing methods. Then, using this update method and based on the longitude angle of the current intersection point, the longitude of the previous intersection point is updated, and the longitude of the current intersection point is determined based on the updated longitude.

[0080] To determine the meridional angle at the current intersection point, first check if the geocentric angle at the current intersection point is zero. If the geocentric angle is zero, then the meridional angle at the current intersection point is set to zero. If the geocentric angle is not zero, then determine the angle between the current line of sight and the parallel of latitude. If the angle between the current line of sight and the parallel of latitude is 90 degrees, it indicates that the observation is currently along a meridian, and the meridional angle at the current intersection point is set to zero. If the angle between the current line of sight and the parallel of latitude is not 90 degrees, it indicates that the observation is not currently along a meridian. In this case, based on the geocentric angle at the current intersection point, the angle between the current line of sight and the parallel of latitude, and the latitude of the current intersection point, the meridional angle at the current intersection point is determined. The formula for calculating the meridional angle at the current intersection point is: , Indicates the latitude of the current intersection point.

[0081] After determining the meridional angle at the current intersection point, if the meridional angle is not zero, then determine the angle between the current line of sight and the due east direction. If the angle between the current line of sight and the due east direction is between -90 and 90 degrees, then the longitude update method is set to longitude increment. If the angle between the current line of sight and the due east direction is between -180 and -90 degrees or between 90 and 180 degrees, then the longitude update method is set to longitude decrement.

[0082] If the longitude update method is longitude increment, the longitude of the previous intersection point is incremented based on the meridional angle of the current intersection point to obtain the updated longitude. That is, the updated longitude = the longitude of the previous intersection point + the meridional angle of the current intersection point. Then, it is determined whether the updated longitude is greater than 180 degrees. If the updated longitude is not greater than 180 degrees, it is set as the longitude of the current intersection point. If the updated longitude is greater than 180 degrees, 360 degrees is subtracted from the updated longitude to obtain the longitude of the current intersection point. That is, the longitude of the current intersection point = the updated longitude - 360 degrees, thus converting the longitude of the current intersection point to west longitude.

[0083] If the longitude update method is a longitude decrementing method, the longitude of the previous intersection point is decremented based on the meridional angle of the current intersection point to obtain the updated longitude. That is, the updated longitude = the longitude of the previous intersection point - the meridional angle of the current intersection point. Then, it is determined whether the updated longitude is less than -180 degrees. If the updated longitude is not less than -180 degrees, it is determined as the longitude of the current intersection point. If the updated longitude is less than -180 degrees, 360 degrees is added to the updated longitude to obtain the longitude of the current intersection point. That is, the longitude of the current intersection point = the updated longitude + 360 degrees, thus converting the longitude of the current intersection point to east longitude.

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

[0085] Furthermore, since the Earth is an ellipsoid, its radius varies at different locations. The distance from the current intersection point to the Earth's center (i.e., the distance to the Earth's center) equals the height of the atmospheric layer at the current intersection point plus the Earth's radius at that point. Therefore, the Earth's radius at the current intersection point can be determined based on the latitude of that point. The formula for calculating the Earth's radius at the current intersection point is: .

[0086] After determining the latitude and longitude of the current intersection point, the coordinates of each intersection point are determined based on their latitude and longitude and the atmospheric layer height where each intersection point is located. The intersection points are then connected based on their coordinates to obtain the initial tracking trajectory. This initial tracking trajectory is then smoothed to address the unevenness caused by atmospheric parameter inhomogeneities, resulting in a smooth ray tracing trajectory. The trajectory smoothing employs a high-order polynomial fitting method.

[0087] ;

[0088] represents the fitting coefficient; n represents the fitting order, which is usually chosen as order 5. Let x represent the polynomial fitting function, and let x represent the coordinates of the intersection points.

[0089] Step S13: Determine the target grid through which each ray tracing trajectory passes from the preset atmospheric gridded model, and determine the extinction coefficient of each target grid.

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

[0091] Phase 1: According to Beer-Lambert's law, infrared radiation is attenuated during its transmission through the atmosphere. This attenuation is caused by both atmospheric absorption and scattering, and it is related to the distance and wavelength of the radiation transmission. Assuming the radiant extinction of the infrared radiation emitted by the target at point O is M, then after atmospheric attenuation, the radiant extinction of the infrared radiation at point P on the boundary line is... Among them, under homogeneous atmospheric conditions, ; d is the atmospheric extinction coefficient, and d is the distance from the target to the boundary line. The boundary line is used to distinguish between the high-density atmosphere and the low-density atmosphere. That is, the boundary line is the boundary line of the high-density atmosphere at a preset height from the Earth's surface. At this time, the distance from the boundary line to the Earth's surface is the preset height.

[0092] Phase Two: Infrared radiation propagates through the low-density atmosphere. Since the satellite is very far from the target, the target can be considered a point source. Therefore, the radiation intensity I received by the camera on the satellite is:

[0093] ;

[0094] Where R is the distance from the satellite to the boundary line; This is a geometric factor of radiation, reflecting 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 vary in distribution 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] Let the value of AOD be... , which is the integral of the atmospheric extinction coefficient in the vertical direction, i.e. The top of the high-density atmosphere (That is, the preset height) is the height of the discontinuous interface of turbulent characteristics, corresponding to the point of maximum curvature of the Logistic curve. Further identification of the height of the high-density atmosphere is given by H. From this, we can obtain... .

[0103] Furthermore, since the atmospheric extinction coefficient and atmospheric visibility satisfy Koschmieder's formula, the near-surface atmospheric extinction coefficient (i.e., the extinction coefficient at an altitude of 0 meters above the Earth's surface) retrieved using this formula is: ,at this time .

[0104] The model parameters can be solved by combining the above formulas. , , Based on this, a Logistic model of the vertical distribution of atmospheric extinction coefficient is obtained. According to the Logistic model of the vertical distribution of atmospheric extinction coefficient and the height of each grid from the Earth's surface, the extinction coefficient of several grids can be determined.

[0105] In Method 2, since the extinction coefficient is determined by two factors—the number of aerosol particles in the atmosphere and the extinction cross section—and the extinction cross section is related to particle type, size, and wavelength, if the aerosol composition and spectral distribution do not change with altitude, the extinction cross section also does not change with altitude z above the Earth's surface. Therefore, the following equation is obtained:

[0106] ;

[0107] In the formula: This represents the extinction coefficient at a height of 0 meters above the Earth's surface. The extinction coefficient is denoted as N(0) at a height of z above the Earth's surface; the aerosol concentration at a height of 0 above the Earth's surface is denoted as N(z).

[0108] Assuming that under the influence of Earth's gravity, aerosol density decreases exponentially with altitude, that is... ;in, It represents atmospheric elevation in km, and can be approximated by the height of the boundary line (i.e., the preset height).

[0109] By combining the above formulas, the negative exponential model of the vertical distribution of atmospheric extinction coefficient can be solved. Based on the negative exponential model of the vertical distribution of atmospheric extinction coefficient and the height of each grid from the Earth's surface, the extinction coefficient of several grids can be determined.

[0110] After constructing the pre-defined atmospheric gridded model, it is necessary to determine the target grid through which each ray tracing trajectory passes from the pre-defined atmospheric gridded model, such as... Figure 4 As shown, the red line represents the ray tracing trajectory, and the blue line box represents the target grid through which the ray tracing trajectory passes in the preset atmospheric gridded model. At the same time, it is necessary to determine the extinction coefficient of each target grid from the preset atmospheric gridded model.

[0111] Step S14: Using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes, construct a target function of radiation intensity ratio with respect to the height of the target from the Earth's surface.

[0112] In this embodiment of the invention, a formula for the ratio of two infrared radiation intensities in different bands at the same time is determined based on a preset radiation intensity calculation formula. The preset radiation intensity calculation formula is an exponential formula for calculating radiation intensity with respect to the distance of infrared radiation transmitted from the target to the boundary line and the extinction coefficient. The boundary line is used to distinguish between the high-density atmosphere and the low-density atmosphere. Using the ratio formula, and based on the extinction coefficient of the target grid traversed by each ray tracing trajectory, and the distance traveled by each ray tracing trajectory in each target grid, an objective function of the radiation intensity ratio with respect to the height of the target above the Earth's surface is constructed. The distance traveled by each ray tracing trajectory in each target grid is determined based on the height of each target grid above the Earth's surface.

[0113] This embodiment of the invention takes into account the condition of a homogeneous atmosphere, and the preset formula for calculating radiation intensity is as follows: Assume that at the same moment, the radiation intensity at a height z above the Earth's surface on band i is... The radiation intensity at a height z above the Earth's surface on band j is At this moment, the formula for the ratio of the two radiation intensities on band i and band j is: .in, and These represent the radiance of infrared radiation at the target location on bands i and j, respectively. This represents the distance infrared radiation travels from the target to a height z above the Earth's surface. and These represent the extinction coefficients at a height z above the Earth's surface on bands i and j, respectively.

[0114] Since the ratio formula is a transcendental equation, it is difficult to solve for the distance. The analytical solution shows that the radiation intensity ratio and distance... The extinction coefficient exhibits an exponential function relationship. However, in practical applications, the atmospheric extinction coefficient is constantly changing. To address this issue, this application introduces a pre-defined atmospheric gridded model, treating the extinction coefficient of each grid in the model as identical. Furthermore, this application determines the target grid traversed by each ray tracing trajectory from the pre-defined atmospheric gridded model and determines the extinction coefficient of each target grid. As the ray tracing trajectory accumulates during transmission, the radiation intensity on the complete trajectory can be obtained by cascading and multiplying the ratios between the bands of each target grid. At this point, based on the extinction coefficient of each target grid traversed by the ray tracing trajectory and the distance traveled by each ray tracing trajectory in each target grid, the ratio formula can be converted to:

[0115] ;

[0116] in, Indicates the radiation intensity ratio; m represents the total number of target grids traversed by each ray tracing trajectory; This represents the height of the k-th target grid above the Earth's surface; This represents the distance traveled by each ray tracing trajectory in the k-th target grid. Furthermore, the distance traveled by each ray tracing trajectory in each target grid can be determined based on the height of each target grid above the Earth's surface. Therefore, the above ratio formula has only one variable, which is... In other words, the above ratio formula can be viewed as a formula about By fitting the discrete function to the ratio formula, a continuous function relating the height of the target above the Earth's surface can be obtained. At this point, the continuous function is the objective function of the radiation intensity ratio with respect to the height of the target above the Earth's surface.

[0117] Step S15: Based on the objective function and the target radiation intensity ratio, determine the target height of the measured target from the Earth's surface.

[0118] Step S16: Determine the position of the target based on the trajectory points in each ray tracing trajectory that match the target height, and determine the line-of-sight vector after atmospheric refraction correction based on the position of the target and the position of the satellite.

[0119] In this embodiment of the invention, the target radiation intensity ratio is substituted into the objective function of the radiation intensity ratio with respect to the height of the target above the Earth's surface to determine the target height of the measured target above the Earth's surface. Then, trajectory points matching the target height are determined from each ray tracing trajectory to obtain the position of the measured target. Finally, 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.

[0120] Determining the trajectory point that matches the target height from each ray tracing trajectory specifically includes: querying the trajectory points in each ray tracing trajectory based on the target height, and determining whether a trajectory point matching the target height is found; if no match is found, then performing trajectory point interpolation on each ray tracing trajectory based on the target height to obtain the trajectory point matching the target height.

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

[0122] Therefore, this application utilizes the fact that atmospheric transmittance varies across different infrared radiation bands, resulting in varying radiation intensities across these bands. Consequently, the target radiation intensity ratio determined based on these different bands also varies. Since the target radiation intensity ratio changes with the target's altitude above the Earth's surface, this application employs ray tracing of the satellite's line of sight to obtain the corresponding ray tracing trajectory. Then, based on the extinction coefficient of the target grid passed through by each ray tracing trajectory in the preset atmospheric gridded model, and the preset radiation intensity calculation formula, a target function for the radiation intensity ratio with respect to the target's altitude above the Earth's surface is constructed. By utilizing this target function and the known target radiation intensity ratio, the target altitude above the Earth's surface can be determined more accurately. Finally, the target altitude above the Earth's surface is used to correct the line-of-sight vector from the satellite to the target, achieving high-precision atmospheric refraction correction under single-satellite observation conditions.

[0123] See Figure 5 As shown, this embodiment of the invention discloses a single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging, comprising:

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

[0125] The light tracing module 12 is used to acquire the observation lines of satellites on different bands at the same time to the target under test, and to perform light tracing on each observation line to obtain the corresponding light tracing trajectory.

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

[0127] The objective function construction module 14 is used to construct an objective function of the radiation intensity ratio with respect to the height of the target from the Earth's surface by using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes.

[0128] The target height determination module 15 is used 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;

[0129] The atmospheric refraction correction module 16 is used to determine the position of the target under test based on the trajectory points that match the target height in each ray tracing trajectory, and to determine the line-of-sight vector after atmospheric refraction correction based on the position of the target under test and the position of the satellite.

[0130] Therefore, this application utilizes the fact that atmospheric transmittance varies across different infrared radiation bands, resulting in varying radiation intensities across these bands. Consequently, the target radiation intensity ratio determined based on these different bands also varies. Since the target radiation intensity ratio changes with the target's altitude above the Earth's surface, this application employs ray tracing of the satellite's line of sight to obtain the corresponding ray tracing trajectory. Then, based on the extinction coefficient of the target grid passed through by each ray tracing trajectory in the preset atmospheric gridded model, and the preset radiation intensity calculation formula, a target function for the radiation intensity ratio with respect to the target's altitude above the Earth's surface is constructed. By utilizing this target function and the known target radiation intensity ratio, the target altitude above the Earth's surface can be determined more accurately. Finally, the target altitude above the Earth's surface is used to correct the line-of-sight vector from the satellite to the target, achieving high-precision atmospheric refraction correction under single-satellite observation conditions.

[0131] In some specific embodiments, the target being measured and the satellite are located in a high-density atmosphere and a low-density atmosphere, respectively; the high-density atmosphere is the region within the atmosphere that is within a predetermined altitude from the Earth's surface; the low-density atmosphere is the region within the atmosphere that is outside the predetermined altitude from the Earth's surface.

[0132] In some specific embodiments, the light tracking module 12 includes:

[0133] The intersection point determination unit is used to determine the intersection point between each observation line of sight after atmospheric refraction and each atmospheric layer; each atmospheric layer is a layer obtained by dividing the high-density atmospheric layer.

[0134] A coordinate determination unit is used to determine the coordinates of each intersection point based on the latitude and longitude of each intersection point and the layer height of the corresponding atmospheric layer;

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

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

[0137] A grid division unit is used to divide the high-density atmosphere into several grids according to latitude, longitude, and altitude.

[0138] An extinction coefficient calculation unit is used to calculate the extinction coefficient of the aforementioned grids based on pre-published global aerosol optical thickness and the height of each grid from the Earth's surface.

[0139] The model building unit is used to build the preset atmospheric gridded model based on the plurality of grids and the extinction coefficients of the plurality of grids.

[0140] In some specific embodiments, the objective function construction module 14 includes:

[0141] The ratio formula determination unit is used to determine the ratio formula of two radiation intensities of the infrared radiation at the same time in different bands 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 transmitted from the target to the boundary line and the extinction coefficient; the boundary line is used to distinguish the high-density atmosphere and the low-density atmosphere.

[0142] A function construction unit is used to construct a target function of the radiation intensity ratio with respect to the height of the target relative to the Earth's surface, based on the ratio formula and the extinction coefficient of the target grid traversed by each ray tracing trajectory and the distance traveled by each ray tracing trajectory in each target grid; wherein the distance traveled by each ray tracing trajectory in each target grid is determined based on the height of each target grid relative to the Earth's surface.

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

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

[0145] The trajectory point interpolation unit is used to perform trajectory point interpolation on each ray tracing trajectory based on the target height if no match is found, so as to obtain a trajectory point that matches the target height.

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

[0147] The coordinate system transformation unit is used to transform the position of the measured target and the position of the satellite into the geocentric inertial coordinate system to obtain the corresponding target coordinates and satellite coordinates;

[0148] An initial vector acquisition unit is used to obtain an initial line-of-sight vector by subtracting the satellite coordinates from the target coordinates;

[0149] The normalization unit is used to normalize the initial line-of-sight vector to obtain the line-of-sight vector after atmospheric refraction correction.

[0150] Finally, the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0151] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0152] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for correcting atmospheric refraction along the line of sight of a single-star target based on multi-spectral ranging, characterized in that, include: The first and second radiation intensities of infrared radiation emitted by the target at different wavelengths at the same time are obtained, and the target radiation intensity ratio is determined based on the first and second radiation intensities. 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 corresponding light tracing trajectory. The target grid through which each ray tracing trajectory passes is determined from the preset atmospheric gridded model, and the extinction coefficient of each target grid is determined; Using a pre-defined formula for calculating radiation intensity and based on the extinction coefficient of the target grid through which each ray tracing trajectory passes, a target function of radiation intensity ratio with respect to the height of the target from the Earth's surface is constructed. Based on the objective function and the target radiation intensity ratio, the target height of the measured target above the Earth's surface is determined; The position of the target is determined based on the trajectory points in each ray tracing trajectory that match the target height, and the atmospheric refraction-corrected line-of-sight vector is determined based on the position of the target and the position of the satellite.

2. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to claim 1, characterized in that, The target being measured and the satellite are located in a high-density atmosphere and a low-density atmosphere, respectively. The high-density atmosphere is the region within the atmosphere at a predetermined altitude above the Earth's surface. The low-density atmosphere is the region within the atmosphere at a predetermined altitude above the Earth's surface.

3. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to claim 2, characterized in that, The step of tracing the light trail for each observation line of sight to obtain the corresponding ray tracing trajectory includes: Determine the intersection point between each observation line of sight after atmospheric refraction and each atmospheric layer; each atmospheric layer is a layer obtained by dividing the high-density atmospheric layer. The coordinates of each intersection point are determined based on the latitude and longitude of each intersection point and the corresponding atmospheric layer height. The intersection points are connected and smoothed based on their coordinates to obtain the corresponding ray tracing trajectory.

4. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to claim 2, characterized in that, The construction process of the preset atmospheric gridded model includes: The high-density atmosphere is divided into several grids according to latitude, longitude, and altitude; Based on the pre-published global aerosol optical thickness and the height of each grid from the Earth's surface, the extinction coefficients of the aforementioned grids are calculated. Based on the aforementioned grids and their extinction coefficients, the preset atmospheric gridded model is constructed.

5. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to claim 4, characterized in that, The process of constructing a target function of radiation intensity ratio with respect to the height of the target above the Earth's surface, using a preset radiation intensity calculation formula and based on the extinction coefficient of the target grid traversed by each ray tracing trajectory, includes: Based on a preset radiation intensity calculation formula, a formula is used to determine the ratio of two radiation intensities in different bands of infrared radiation at the same time; the preset radiation intensity calculation formula is an exponential formula for calculating radiation intensity with respect to the distance the infrared radiation travels from the target to the boundary line and the extinction coefficient; the boundary line is used to distinguish between the high-density atmosphere and the low-density atmosphere. Using the ratio formula, and based on the extinction coefficient of the target grid traversed by each ray tracing trajectory and the distance traveled by each ray tracing trajectory in each target grid, a target function of the radiation intensity ratio with respect to the height of the target above the Earth's surface is constructed; wherein, the distance traveled by each ray tracing trajectory in each target grid is determined based on the height of each target grid above the Earth's surface.

6. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to claim 1, characterized in that, Before determining the position of the target based on the trajectory points in each ray tracing trajectory that match the target height, the method further includes: Based on the target height, the trajectory points in each ray tracing trajectory are queried, and it is determined whether a trajectory point matching the target height is found. If no match is found, trajectory point interpolation is performed on each ray tracing trajectory based on the target height to obtain trajectory points that match the target height.

7. The method for atmospheric refraction correction of a single-star target line of sight based on multi-spectral ranging according to any one of claims 1 to 6, characterized in that, Determining the line-of-sight vector after atmospheric refraction correction based on the position of the target being measured and the position of the satellite includes: The positions of the target and the satellite are transformed into a geocentric inertial coordinate system to obtain the corresponding target coordinates and satellite coordinates. The initial line-of-sight vector is obtained by subtracting the satellite coordinates from the target coordinates; The initial line-of-sight vector is normalized to obtain the line-of-sight vector corrected for atmospheric refraction.

8. A single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging, characterized in that, include: The radiation intensity ratio determination module is used to acquire the first radiation intensity and the second radiation intensity of the infrared radiation emitted by the target at different wavelengths at the same time, and to determine the target radiation intensity ratio based on the first radiation intensity and the second radiation intensity. The light tracing module is used to acquire the observation lines of satellites on different bands at the same time to the target under test, and to perform light tracing on each observation line to obtain the corresponding light tracing trajectory; The extinction coefficient determination module is used to determine the target grid through which each ray tracing trajectory passes from a preset atmospheric gridded model, and to determine the extinction coefficient of each target grid. The objective function construction module is used to construct an objective function of the radiation intensity ratio with respect to the height of the target from the Earth's surface, based on a preset radiation intensity calculation formula and the extinction coefficient of the target grid through which each ray tracing trajectory passes. The target height determination module is used 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; The atmospheric refraction correction module is used to determine the position of the target under test based on the trajectory points in each ray tracing trajectory that match the target height, and to determine the line-of-sight vector after atmospheric refraction correction based on the position of the target under test and the position of the satellite.

9. The single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging according to claim 8, characterized in that, Also includes: The trajectory point query unit is used to query the trajectory points in each ray tracing trajectory based on the target height, and determine whether a trajectory point matching the target height is found. The trajectory point interpolation unit is used to perform trajectory point interpolation on each ray tracing trajectory based on the target height if no match is found, so as to obtain a trajectory point that matches the target height.

10. The single-star target line-of-sight atmospheric refraction correction system based on multi-spectral ranging according to claim 8 or 9, characterized in that, The atmospheric refraction correction module includes: The coordinate system transformation unit is used to transform the position of the measured target and the position of the satellite into the geocentric inertial coordinate system to obtain the corresponding target coordinates and satellite coordinates; An initial vector acquisition unit is used to obtain an initial line-of-sight vector by subtracting the satellite coordinates from the target coordinates; The normalization unit is used to normalize the initial line-of-sight vector to obtain the line-of-sight vector after atmospheric refraction correction.

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