Starlight refraction information calculation method and device based on two-section type fine ray tracing

Abstract

The invention relates to a starlight refraction information calculation method and device based on two-section type fine ray tracing. The method comprises the following steps: determining refractive index distribution of all atmospheric layers in a starlight refraction propagation path according to a global three-dimensional atmospheric refractive index field, subdividing the space between two layers of atmosphere of a vector into multiple layers, calculating the refractive index of each fine layer, and calculating the refractive index of each fine layer; and then calculating the refraction angle variable quantity of the starlight passing through the fine layering and the height variable quantity of the refraction generation position to the earth center of the first starlight path and the second starlight path, and summing the obtained refraction angle variable quantity to obtain the starlight total refraction angle of the light passing through the atmosphere. Compared with an empirical starlight atmospheric refraction model, the method has the advantages that the refraction path of the starlight passing through the global atmosphere can be accurately simulated by utilizing a two-section type fine ray tracing method, and the simplification error caused by the empirical starlight atmospheric refraction model during starlight refraction simulation is avoided; and the precision of refraction information such as a starlight refraction angle and a starlight refraction apparent height is improved.

Description

Technical Field

[0001] The present application relates to the field of celestial navigation technology, and in particular to a method and device for calculating starlight refraction information based on two-stage fine ray tracing. Background Art

[0002] In the autonomous navigation of starlight atmospheric refraction, information such as the starlight refraction angle and the apparent height of starlight refraction formed when starlight passes through the atmosphere is crucial. In the simulation of the starlight atmospheric simulation system, it is necessary to accurately calculate the refraction path of starlight passing through the atmosphere, and obtain information such as the starlight refraction angle and the apparent height of starlight refraction for subsequent simulation. When solving the starlight atmospheric refraction navigation, the autonomous positioning of the spacecraft can be achieved based on the geometric constraint relationship between the apparent height of starlight refraction and the position of the spacecraft. In order to ensure the positioning accuracy of the starlight atmospheric refraction navigation system, it is necessary to ensure the accuracy of the spacecraft in obtaining the apparent height of starlight refraction.

[0003] Usually, the starlight refraction angle and starlight refraction apparent altitude are obtained by calculating the empirical starlight atmospheric refraction model. When the model is established, the refraction process of starlight passing through the atmosphere is simplified, and the USSA1976 reference atmospheric model is used to describe the refraction process, without considering the changes in global atmospheric parameters. Therefore, the accuracy of the refraction information such as the starlight refraction angle and starlight refraction apparent altitude obtained by the empirical model cannot be guaranteed. Summary of the invention

[0004] Based on this, it is necessary to provide a method and device for calculating starlight refraction information based on two-stage fine ray tracing, which can ensure the calculation accuracy of refraction information such as starlight refraction angle and refraction apparent height, in order to address the above technical problems.

[0005] A method for calculating starlight refraction information based on two-stage fine ray tracing, the method comprising: Step 1: Based on the global three-dimensional atmospheric refractive index field, determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path.

[0006] Step 2: In k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0.

[0007] Step 3: Calculate the starlight zenith angle of the fine layer in the first segment of the starlight path based on the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere.

[0008] Step 4: According to the height of the fine layer, the starlight zenith angle and refractive index of the corresponding fine layer, k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs.

[0009] Step 5: According to the starlight zenith angle, determine whether the first segment of the starlight path meets the minimum refraction cut height. If not, continue the process from step 3 to step 4 until the requirement is met. If it is met, determine the starlight refraction apparent height according to the starlight cut height and the refraction index at the starlight cut height.

[0010] Step 6: Repeat the process from step 3 to step 4, replacing the first segment of the starlight path with the second segment of the starlight path, and determine the change in the refraction angle of the starlight passing through the fine layer in the second segment of the starlight path and the change in the height from the center of the earth where the refraction occurs, until the starlight passes through the highest atmospheric layer.

[0011] Step 7: Determine the total refraction angle of starlight passing through the atmosphere based on the sum of the changes in the refraction angle of starlight passing through the fine layers in the first and second starlight paths.

[0012] In one embodiment, in k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer is determined as:

[0013]

[0014] in, For the i The refractive index of the fine layer, For the i The height of the fine layer, , For the distance between each fine layer, and Respectively k+ 1st floor and k Layer height, and Respectively k+ 1st floor and k The refractive index of the atmosphere.

[0015] In one embodiment, the starlight zenith angle of the fine layer in the first segment of the starlight path is calculated according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere:

[0016] in, The first starlight path i A finely layered zenith angle of starlight, is the height of the highest atmosphere, is the refractive index of the highest atmospheric layer, For the i The height of the fine layer, For the i The refractive index of a fine layer, It is the zenith angle of starlight at the highest level of the atmosphere.

[0017] In one embodiment, the changes in the refraction angles of the starlight passing through the fine layers in the first segment of the starlight path in step 4 are respectively:

[0018]

[0019]

[0020]

[0021] in, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, and Respectively Layer and k The refractive index of the atmosphere, and Respectively k+ 1st floor and k Layer height, For the i The refractive index of the fine layer, is the conversion variable, The first starlight path i A finely layered zenith angle of starlight, For the i The height of the fine layer.

[0022] In one embodiment, the change in height from the center of the earth where the refraction of the starlight passing through the fine layer occurs in the first segment of the starlight path is:

[0023] in, The first segment of the starlight path is the starlight passing through i The change in altitude from the center of the earth where fine-grained refraction occurs.

[0024] In one embodiment, the constraint formula for determining whether the first segment of the starlight path satisfies the minimum refraction cut height is:

[0025] in, The first starlight path i A finely layered zenith angle of starlight, To set the threshold.

[0026] In one embodiment, the apparent altitude of starlight refraction is:

[0027] in, is the apparent height due to the refraction of starlight, Starlight cut height The refractive index at is the radius of the Earth.

[0028] In one embodiment, the total refraction angle of starlight passing through the atmosphere is determined based on the sum of the changes in the refraction angle of starlight passing through fine layers in the first segment of the starlight path and the second segment of the starlight path:

[0029] in, R is the total refraction angle of starlight passing through the atmosphere, M and N are the number of atmospheric layers that the two starlight paths pass through, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, The second segment of the starlight path is the starlight passing through i The amount of refraction angle variation for fine layers.

[0030] A device for calculating starlight refraction information based on two-stage fine ray tracing, the device comprising: The refractive index distribution determination module of the atmospheric layer is used to determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path according to the global three-dimensional atmospheric refractive index field.

[0031] Fine-grained refractive index determination module for the k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and thek+ 1st floor and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0.

[0032] The module for calculating the starlight zenith angle of the fine layer is used to calculate the starlight zenith angle of the fine layer in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere.

[0033] The calculation module of the refraction angle change and the height change of the refraction point from the center of the earth is used to calculate the refraction angle change according to the height of the fine layer, the starlight zenith angle and refraction index of the corresponding fine layer, and the k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs.

[0034] The module for determining the apparent height of starlight refraction is used to determine whether the first segment of the starlight path meets the minimum refraction tangent height according to the starlight zenith angle. If not, the module for calculating the change in refraction angle and the change in height from the center of the earth at which the refraction occurs and the module for determining the apparent height of starlight refraction are repeatedly executed until the requirements are met. If so, the module for determining the apparent height of starlight refraction is determined according to the starlight tangent height and the refraction index at the starlight tangent height.

[0035] The second segment starlight path ray tracing module is used to repeatedly execute the refraction angle change and the change in height from the center of the earth where the refraction occurs calculation module and the starlight refraction apparent height determination module, replace the first segment starlight path with the second segment starlight path, determine the refraction angle change of the starlight passing through the fine layer and the change in height from the center of the earth where the refraction occurs in the second segment starlight path, until the starlight passes through the highest atmospheric layer.

[0036] The module for determining the total refraction angle of starlight passing through the atmosphere is used to determine the total refraction angle of starlight passing through the atmosphere according to the sum of the refraction angle changes of the starlight passing through the fine layers in the first segment of the starlight path and the second segment of the starlight path.

[0037] The above-mentioned method and device for calculating the starlight refraction information based on two-stage fine ray tracing, the method determines the refraction index distribution of all atmospheric layers in the starlight refraction propagation path according to the global three-dimensional atmospheric refraction index field, subdivides the vector between the two atmospheric layers into multiple layers, calculates the refraction index of each fine layer, and then calculates the change in the refraction angle of the starlight passing through the fine layer and the change in the height from the center of the earth where the refraction occurs in the first segment of the starlight path and the second segment of the starlight path, sums the obtained change in the refraction angle, and obtains the total refraction angle of the starlight passing through the atmosphere. Compared with the empirical starlight atmospheric refraction model, the present method can accurately simulate the refraction path of starlight passing through the global atmosphere by using the two-stage fine ray tracing method, avoids the simplification error brought by the empirical starlight atmospheric refraction model when simulating starlight refraction; and improves the accuracy of refraction information such as the starlight refraction angle and the apparent height of the starlight refraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flowchart of a method for calculating starlight refraction information based on two-stage fine ray tracing in one embodiment; Figure 2 A flow chart of a two-stage fine ray tracing method for calculating starlight refraction information in one embodiment; Figure 3 Graphs showing the result of calculating starlight refraction information using a two-stage fine ray tracing method in one embodiment, wherein (a) is a graph showing the result of calculating the starlight refraction angle, and (b) is a graph showing the result of calculating the starlight refraction apparent height; Figure 4 It is a structural block diagram of a device for calculating starlight refraction information based on two-stage fine ray tracing in one embodiment. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] In one embodiment, Figure 1 , Figure 2 As shown, a method for calculating starlight refraction information based on two-stage fine ray tracing is provided. This method is applicable to the autonomous navigation system for starlight atmospheric refraction, and can accurately obtain the refraction information of starlight passing through the atmosphere, such as the starlight refraction angle and the starlight refraction apparent altitude. Taking a low-orbit spacecraft as an example, the method includes the following steps: Step 1: Based on the global three-dimensional atmospheric refractive index field, determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path.

[0041] Specifically, based on the ERA5 global atmospheric reanalysis dataset released by the European Centre for Medium-Range Weather Forecasts, the global atmospheric refractive index field in the optical band is obtained, and the refractive index distribution of all atmospheric layers in the starlight refraction propagation path is determined based on the global atmospheric refractive index field.

[0042] Step 2: In k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0.

[0043] Specifically, the k+ 1st floor and k The atmosphere is divided into 10 layers, and the distance between each fine layer is 100m. The height of the fine layer is for:

[0044] in, .

[0045] Step 3: Calculate the starlight zenith angle of the fine layer in the first segment of the starlight path based on the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere.

[0046] Specifically, at the highest altitude in the atmosphere , the refractive index of the highest atmospheric layer Under the condition of , calculate the starlight zenith angle of each fine layer in the first starlight path.

[0047] Step 4: According to the height of the fine layer, the starlight zenith angle and refractive index of the corresponding fine layer, k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs.

[0048] Step 5: According to the starlight zenith angle, determine whether the first segment of the starlight path meets the minimum refraction cut height. If not, continue the process from step 3 to step 4 until the requirement is met. If it is met, determine the starlight refraction apparent height according to the starlight cut height and the refraction index at the starlight cut height.

[0049] Step 6: Repeat the process from step 3 to step 4, replacing the first segment of the starlight path with the second segment of the starlight path, and determine the change in the refraction angle of the starlight passing through the fine layer in the second segment of the starlight path and the change in the height from the center of the earth where the refraction occurs, until the starlight passes through the highest atmospheric layer.

[0050] Step 7: Determine the total refraction angle of starlight passing through the atmosphere based on the sum of the changes in the refraction angle of starlight passing through the fine layers in the first and second starlight paths.

[0051] In the above-mentioned method for calculating the starlight refraction information based on two-stage fine ray tracing, the method determines the refraction index distribution of all atmospheric layers in the starlight refraction propagation path according to the global three-dimensional atmospheric refraction index field, subdivides the vector between the two atmospheric layers into multiple layers, calculates the refraction index of each fine layer, and then calculates the change in the refraction angle of the starlight passing through the fine layer and the change in the height from the center of the earth where the refraction occurs in the first segment of the starlight path and the second segment of the starlight path, and sums the obtained change in the refraction angle to obtain the total refraction angle of the starlight passing through the atmosphere. Compared with the empirical starlight atmospheric refraction model, this method can accurately simulate the refraction path of starlight passing through the global atmosphere by using the two-stage fine ray tracing method, avoiding the simplification error brought by the empirical starlight atmospheric refraction model when simulating starlight refraction; and improves the accuracy of refraction information such as the starlight refraction angle and the apparent height of the starlight refraction.

[0052] In one embodiment, step 2 comprises: k+ 1st floor and k The atmosphere is divided into layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer is determined as:

[0053]

[0054] in, For the i The refractive index of the fine layer, For the i The height of the fine layer, , For the distance between each fine layer, and Respectively k+ 1st floor and k Layer height, and Respectively k+ 1st floor and k The refractive index of the atmosphere.

[0055] In one embodiment, step 3 includes: calculating the starlight zenith angle of the fine layer in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere:

[0056] in, The first starlight path i A finely layered zenith angle of starlight, is the height of the highest atmosphere, is the refractive index of the highest atmospheric layer, For the i The height of the fine layer, For the i The refractive index of a fine layer, It is the zenith angle of starlight at the highest level of the atmosphere.

[0057] In one embodiment, the changes in the refraction angles of the starlight passing through the fine layers in the first segment of the starlight path in step 4 are respectively:

[0058]

[0059]

[0060]

[0061] in, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, and Respectively k+ 1st floor and k The refractive index of the atmosphere, and Respectively k+ 1st floor and k Layer height, For the i The refractive index of the fine layer, is the conversion variable, The first segment of the starlight path i A finely layered zenith angle of starlight, For the i The height of the fine layer.

[0062] In one embodiment, the change in height from the center of the earth at the point where the refraction of the starlight passing through the fine layer in the first segment of the starlight path in step 4 occurs is:

[0063] in, The first segment of the starlight path is the starlight passing through i The change in altitude from the center of the earth where fine-grained refraction occurs.

[0064] In one embodiment, the constraint formula for determining whether the first segment of the starlight path satisfies the minimum refraction cut height in step 5 is:

[0065] in, The first segment of the starlight path i A finely layered zenith angle of starlight, To set the threshold.

[0066] In one embodiment, the apparent altitude of starlight refraction is:

[0067] in, is the apparent height due to the refraction of starlight, Starlight cut height The refractive index at is the radius of the Earth.

[0068] In one embodiment, step 7 includes: determining the total refraction angle of starlight passing through the atmosphere according to the sum of the changes in the refraction angle of starlight passing through the fine layers in the first segment of the starlight path and the second segment of the starlight path:

[0069] in, R is the total refraction angle of starlight passing through the atmosphere, M and N are the number of atmospheric layers that the two starlight paths pass through, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, The second segment of the starlight path is the starlight passing through i The amount of refraction angle variation for fine layers.

[0070] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0071] In a verification example, a low-orbit spacecraft is used as the simulation object, and 31 Dec 2023 12:00:00.000 UTCG is used as the simulation start time. The orbital elements of the low-orbit spacecraft are: semi-major axis ; Eccentricity ; Orbital inclination ; Ascending node right ascension ; Pericenter angular distance True anomaly .

[0072] The results of using the two-stage fine ray tracing method to calculate the starlight refraction information are as follows Figure 3 As shown, (a) is the calculation result of the starlight refraction angle, and (b) is the calculation result of the starlight refraction apparent height.

[0073] In one embodiment, Figure 4 As shown, a starlight refraction information calculation device based on two-stage fine ray tracing is provided, including: a refractive index distribution determination module of atmospheric stratification, a fine stratified refractive index determination module, a fine stratified starlight zenith angle calculation module, a refraction angle change amount and a refraction occurrence height change amount calculation module from the center of the earth, a starlight refraction apparent height determination module, a second segment starlight path ray tracing module and a starlight total refraction angle determination module when starlight passes through the atmosphere, wherein: The refractive index distribution determination module of the atmospheric layer is used to determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path according to the global three-dimensional atmospheric refractive index field.

[0074] Fine-grained refractive index determination module for the k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0.

[0075] The module for calculating the starlight zenith angle of the fine layer is used to calculate the starlight zenith angle of the fine layer in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere.

[0076] The calculation module of the refraction angle change and the height change of the refraction point from the center of the earth is used to calculate the refraction angle change according to the height of the fine layer, the starlight zenith angle and refraction index of the corresponding fine layer, and the k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs.

[0077] The module for determining the apparent height of starlight refraction is used to determine whether the first segment of the starlight path meets the minimum refraction tangent height according to the starlight zenith angle. If not, the module for calculating the change in refraction angle and the change in height from the center of the earth at which the refraction occurs and the module for determining the apparent height of starlight refraction are repeatedly executed until the requirements are met. If so, the module for determining the apparent height of starlight refraction is determined according to the starlight tangent height and the refraction index at the starlight tangent height.

[0078] The second segment starlight path ray tracing module is used to repeatedly execute the refraction angle change and the change in height from the center of the earth where the refraction occurs calculation module and the starlight refraction apparent height determination module, replace the first segment starlight path with the second segment starlight path, determine the refraction angle change of the starlight passing through the fine layer and the change in height from the center of the earth where the refraction occurs in the second segment starlight path, until the starlight passes through the highest atmospheric layer.

[0079] The module for determining the total refraction angle of starlight passing through the atmosphere is used to determine the total refraction angle of starlight passing through the atmosphere according to the sum of the refraction angle changes of the starlight passing through the fine layers in the first segment of the starlight path and the second segment of the starlight path.

[0080] In one embodiment, the fine layered refractive index determination module is further configured to: k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer is determined as:

[0081]

[0082] in, For the i The refractive index of the fine layer, For the i The height of the fine layer, , For the distance between each fine layer, and Respectively k+ 1st floor and k Layer height, and Respectively k+ 1st floor and k The refractive index of the atmosphere.

[0083] In one embodiment, the fine-layered starlight zenith angle calculation module is further used to calculate the fine-layered starlight zenith angle in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere:

[0084] in, The first starlight path i A finely layered zenith angle of starlight, is the height of the highest atmosphere, is the refractive index of the highest atmospheric layer, For the i The height of the fine layer, For the i The refractive index of a fine layer, It is the zenith angle of starlight at the highest level of the atmosphere.

[0085] In one embodiment, the refraction angle variation and the height variation from the center of the earth at which the refraction occurs in the calculation module are as follows:

[0086]

[0087]

[0088]

[0089] in, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, and Respectively k+ 1st floor and k The refractive index of the atmosphere, and Respectively k+ 1st floor and k Layer height, For the iThe refractive index of the fine layer, is the conversion variable, The first segment of the starlight path i A finely layered zenith angle of starlight, For the i The height of the fine layer.

[0090] In one embodiment, in the calculation module for calculating the change in refraction angle and the change in height from the center of the earth at which the starlight passes through the fine layer in the first segment of the starlight path, the change in height from the center of the earth at which the starlight passes through the fine layer is:

[0091] in, The first segment of the starlight path is the starlight passing through i The change in altitude from the center of the earth where fine-grained refraction occurs.

[0092] In one embodiment, the constraint formula used in the starlight refraction apparent height determination module to determine whether the first segment of the starlight path satisfies the minimum refraction cut height is:

[0093] in, The first segment of the starlight path i A finely layered zenith angle of starlight, To set the threshold.

[0094] In one embodiment, the apparent altitude of starlight refraction is:

[0095] in, is the apparent height due to the refraction of starlight, Starlight cut height The refractive index at is the radius of the Earth.

[0096] In one embodiment, the module for determining the total refraction angle of starlight passing through the atmosphere is further used to determine the total refraction angle of starlight passing through the atmosphere according to the sum of the changes in the refraction angle of starlight passing through the fine layers in the first segment of the starlight path and the second segment of the starlight path:

[0097] in, R is the total refraction angle of starlight passing through the atmosphere, M and N are the number of atmospheric layers that the two starlight paths pass through, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, The second segment of the starlight path is the starlight passing through i The amount of refraction angle variation for fine layers.

[0098] For the specific definition of the starlight refraction information calculation device based on two-stage fine ray tracing, please refer to the definition of the starlight refraction information calculation method based on two-stage fine ray tracing above, which will not be repeated here. Each module in the above-mentioned starlight refraction information calculation device based on two-stage fine ray tracing can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0099] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for calculating starlight refraction information based on two-stage fine ray tracing, characterized in that: The method comprises: Step 1: Based on the global three-dimensional atmospheric refractive index field, determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path; Step 2: In k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0; Step 3: Calculate the starlight zenith angle of the fine layer in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere; Step 4: According to the height of the fine layer, the starlight zenith angle and refractive index of the corresponding fine layer, k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs; Step 5: judging whether the first segment of the starlight path meets the minimum refraction cut height according to the starlight zenith angle, if not, continuing the process from step 3 to step 4 until the requirement is met; if it is met, determining the starlight refraction apparent height according to the starlight cut height and the refraction index at the starlight cut height; Step 6: Repeat the process from step 3 to step 4, replacing the first segment of the starlight path with the second segment of the starlight path, and determine the change in the refraction angle of the starlight passing through the fine layer in the second segment of the starlight path and the change in the height from the center of the earth where the refraction occurs, until the starlight passes through the highest atmospheric layer; Step 7: Determine the total refraction angle of starlight passing through the atmosphere based on the sum of the changes in the refraction angle of starlight passing through the fine layers in the first and second starlight paths.

2. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: In the k+ 1st floor and k The atmosphere is divided into l layer, according to the height of each fine layer and the k+ 1st floor and k The refractive index of the layer is determined as: in, For the i The refractive index of the fine layer, For the i The height of the fine layer, , For the distance between each fine layer, and Respectively k+ 1st floor and k Layer height, , Respectively k+ 1st floor and k The refractive index of the atmosphere.

3. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: According to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere, the starlight zenith angle of the fine layer in the first segment of the starlight path is calculated as: in, The first starlight path i A finely layered zenith angle of starlight, is the height of the highest atmosphere, is the refractive index of the highest atmospheric layer, For the i The height of the fine layer, For the i The refractive index of a fine layer, It is the zenith angle of starlight at the highest level of the atmosphere.

4. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: The changes in the refraction angles of the starlight passing through the fine layers in the first segment of the starlight path in step 4 are: in, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, and Respectively k+ 1st floor and k The refractive index of the atmosphere, and Respectively k+ 1st floor and k Layer height, For the i The refractive index of the fine layer, is the conversion variable, The first segment of the starlight path i A finely layered zenith angle of starlight, For the i The height of the fine layer.

5. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 4, characterized in that: The change in height from the center of the earth where the starlight passes through the fine layer of refraction in the first segment of the starlight path is: in, The first segment of the starlight path is the starlight passing through i The change in altitude from the center of the earth where fine-grained refraction occurs.

6. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: The constraint formula used to determine whether the first segment of the starlight path meets the minimum refraction cut height is: in, The first segment of the starlight path i A finely layered zenith angle of starlight, To set the threshold.

7. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: The apparent height of starlight refraction is: in, is the apparent height due to the refraction of starlight, Starlight cut height The refractive index at is the radius of the Earth.

8. The method for calculating starlight refraction information based on two-stage fine ray tracing according to claim 1, characterized in that: According to the sum of the changes in the refraction angle of the starlight passing through the fine layers in the first and second segments of the starlight path, the total refraction angle of the starlight passing through the atmosphere is determined to be: in, R is the total refraction angle of starlight passing through the atmosphere, M and N are the number of atmospheric layers that the two starlight paths pass through, The first segment of the starlight path is the starlight passing through i The variation of refraction angle of fine layering, The second segment of the starlight path is the starlight passing through i The amount of refraction angle variation for fine layers.

9. A device for calculating starlight refraction information based on two-stage fine ray tracing, characterized in that: The device comprises: A module for determining the refractive index distribution of atmospheric layers, which is used to determine the refractive index distribution of all atmospheric layers in the starlight refraction propagation path according to the global three-dimensional atmospheric refractive index field; Fine-grained refractive index determination module for the Layer and k The atmosphere is divided into l layer, according to the height of each fine layer and the Layer and k The refractive index of the layer determines the refractive index of the fine layer; where, k and l All are integers greater than 0; A fine-layered starlight zenith angle calculation module, used to calculate the fine-layered starlight zenith angle in the first segment of the starlight path according to the height of the fine layer, the refractive index of the corresponding fine layer, and the height and refractive index of the highest atmosphere; The refraction angle change amount and the refraction occurrence height change amount calculation module is used to calculate the refraction angle change amount and the refraction occurrence height change amount according to the height of the fine layer, the starlight zenith angle and refraction index of the corresponding fine layer, the first k+ 1st floor and k The height and refractive index of the layer are used to calculate the change in the refraction angle of the starlight passing through the fine layer in the first segment of the starlight path and the change in the height from the center of the earth where the refraction occurs; The module for determining the apparent height of starlight refraction is used to determine whether the first segment of the starlight path meets the minimum refraction tangent height according to the starlight zenith angle. If not, the module for calculating the change in the refraction angle and the change in the height from the center of the earth at which the refraction occurs and the module for determining the apparent height of starlight refraction are repeatedly executed until the requirements are met. If the requirements are met, the apparent height of starlight refraction is determined according to the starlight tangent height and the refraction index at the starlight tangent height. The second segment starlight path ray tracing module is used to repeatedly execute the refraction angle change amount and the refraction occurrence point from the earth's center height calculation module and the starlight refraction apparent height determination module, replace the first segment starlight path with the second segment starlight path, determine the refraction angle change amount and the refraction occurrence point from the earth's center height change amount of the starlight in the second segment starlight path passing through the fine layer, until the starlight passes through the highest atmospheric layer; The module for determining the total refraction angle of starlight passing through the atmosphere is used to determine the total refraction angle of starlight passing through the atmosphere according to the sum of the refraction angle changes of the starlight passing through the fine layers in the first segment of the starlight path and the second segment of the starlight path.

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