Multi-level spherical grid clustering method and system

Abstract

The invention provides a multi-level spherical grid clustering method and system. The method comprises the following steps: a grid corner point generation step: generating M rows and N columns of grid corner points on a multi-level spherical area; a projection plane establishment step: grouping each layer of grid angular points of the multi-layer spherical area, and establishing a corresponding projection plane; and a projection clustering step: projecting the grid angular points to the projection plane and carrying out clustering. According to the method, correction measures are taken for the error between the projection plane and the earth curved surface, and the error is well eliminated. According to the method, the operation of triangular and anti-trigonometric functions is not involved in the pixel clustering process, so that the real-time performance of the algorithm is ensured. Under the condition that the number of grids is large, a multi-level grid clustering method is adopted, and the real-time performance of the algorithm is further guaranteed.

Description

Technical Field

[0001] The invention relates to the field of remote sensing technology, and in particular to a multi-level spherical grid clustering method and system. Background Art

[0002] Grid Clustering (Grid-based Clustering) is a grid-based clustering method, also known as grid-based aggregation. The basic idea is to cluster based on the density of samples in the grid, which is suitable for discovering density-based clusters in high-dimensional data sets. Specifically, the data set is divided into small grids, and then the density of data points is calculated in each grid, and the grids with higher density are merged into a cluster. This process can be achieved by continuously adjusting the grid size and density threshold.

[0003] In the existing spherical grid clustering methods on the market, when the number of grids is large, the real-time calculation performance in the pixel clustering process is poor.

[0004] Therefore, there is a need in the market for a multi-level spherical grid clustering method and system that can ensure real-time calculation in the pixel clustering process when the number of grids is large. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a multi-level spherical grid clustering method and system.

[0006] A multi-level spherical grid clustering method provided by the present invention comprises:

[0007] Grid corner point generation step: generate M rows and N columns of grid corner points on the multi-level spherical area;

[0008] Projection plane establishment step: grouping each grid corner point of the multi-level spherical area and establishing a corresponding projection plane;

[0009] Projection clustering step: projecting the grid corner points onto the projection plane and performing clustering.

[0010] Preferably, the projection plane establishing step includes the following sub-steps:

[0011] Step S2.1: Initialization, set i=0, M0=M;

[0012] Step S2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Group;

[0013] Step S2.3: establishing a projection plane, wherein the projection plane passes through the center of the sphere and is perpendicular to a line connecting the center of the sphere and the center position of the corresponding grid group on the spherical surface;

[0014] Step S2.4: Determine K i With M i If they are equal, then execute step S2.5; if not, then set M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point is reached, i is incremented by 1 and step S2.2 is executed;

[0015] Step S2.5: Let iMax=i, and the projection plane establishment step is completed.

[0016] Preferably, the projection clustering step includes the following sub-steps:

[0017] Step S3.1: Extract L iMax All rows in the hierarchy are used as projection clusters, let i = iMax;

[0018] Step S3.2: Scatter points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and a projection grid, projection grid corner points and projection scattered points are obtained;

[0019] Step S3.3: establishing an affine auxiliary grid;

[0020] Step S3.4: clustering the projected scattered points into the auxiliary grid;

[0021] Step S3.5: In the auxiliary grid, the projected scattered points are corrected to the projected grid, and the corresponding scattered points are clustered to the corresponding spherical grid;

[0022] Step S3.6: Determine whether i is equal to 0. If so, the projection clustering step ends; if not, execute step S3.7;

[0023] Step S3.7: Take L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1 The row corner point is used as the projection cluster for the next time, i is decremented by 1, and step S3.1 is executed.

[0024] Preferably, the projection grid in step S3.2 refers to the grid in the constructed projection plane;

[0025] The projection grid corner points are grid corner points projected onto the projection plane;

[0026] The projected scatter points refer to scatter points projected onto the projection plane.

[0027] Preferably, the row-wise side lengths of the auxiliary grids in step S3.3 are equal to the row-wise side lengths of the projection grids near the center of the projection grid area or equal to the row-wise side lengths of the projection grids at the corresponding positions near the row-wise center line of the projection grid area;

[0028] The side lengths of the auxiliary grid columns are equal to the side lengths of the projection grid columns near the center of the projection grid area or equal to the side lengths of the projection grid columns at the corresponding positions near the center line of the projection grid area columns.

[0029] A multi-level spherical grid clustering system provided by the present invention comprises:

[0030] Grid corner point generation module: generates M rows and N columns of grid corner points on a multi-level spherical area;

[0031] A projection plane establishment module: groups each grid corner point of the multi-level spherical area and establishes a corresponding projection plane;

[0032] Projection clustering module: projecting the grid corner points onto the projection plane and performing clustering;

[0033] Preferably, the projection plane establishing module includes the following submodules:

[0034] Module M2.1: Initialization, set i=0, M0=M;

[0035] Module M2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Group;

[0036] Module M2.3: Establish a projection plane, which passes through the center of the sphere and is perpendicular to the line connecting the center of the sphere and the center position of the corresponding grid group on the spherical surface;

[0037] Module M2.4: Determine K i With M i If they are equal, then the module M2.5 is triggered; if not, then M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point is reached, i increases by 1, triggering module M2.2;

[0038] Module M2.5: Let iMax=i, and the projection plane establishment module ends.

[0039] Preferably, the projection clustering module includes the following submodules:

[0040] Module M3.1: Extracting L iMaxAll rows in the hierarchy are used as projection clusters, let i = iMax;

[0041] Module M3.2: Scatter Points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and a projection grid, projection grid corner points and projection scattered points are obtained;

[0042] Module M3.3: Establishing affine auxiliary grid;

[0043] Module M3.4: clustering the projected scattered points into the auxiliary grid;

[0044] Module M3.5: In the auxiliary grid, the projected scattered points are corrected to the projected grid, and the corresponding scattered points are clustered to the corresponding spherical grid;

[0045] Module M3.6: Determine whether i is equal to 0. If so, the projection clustering module ends; if not, module M3.7 is triggered;

[0046] Module M3.7: Take L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1 The row corner point is used as the projection cluster for the next time, i is decremented by 1, and module M3.1 is triggered.

[0047] Preferably, the projection grid in module M3.2 refers to the grid in the constructed projection plane;

[0048] The projection grid corner points are grid corner points projected onto the projection plane;

[0049] The projected scatter points refer to scatter points projected onto the projection plane.

[0050] Preferably, the row-wise side lengths of the auxiliary grids in module M3.3 are equal to the row-wise side lengths of the projection grids near the center of the projection grid area or equal to the row-wise side lengths of the projection grids at the corresponding positions near the row-wise center line of the projection grid area;

[0051] The side lengths of the auxiliary grid columns are equal to the side lengths of the projection grid columns near the center of the projection grid area or equal to the side lengths of the projection grid columns at the corresponding positions near the center line of the projection grid area columns.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] In view of the fact that the number of grids is large, the present invention adopts a multi-level grid clustering method to further ensure the real-time performance of the algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0055] Figure 1 It is a schematic diagram of the workflow of the present invention;

[0056] Figure 2 It is a top view of the projection plane in the present invention. DETAILED DESCRIPTION

[0057] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0058] The present invention projects grid corner points and pixel scattered points onto a dynamically generated auxiliary plane and then performs clustering. Correction measures are taken for the error between the projection plane and the earth's curved surface to eliminate the error better. The pixel clustering process of the present invention does not involve the calculation of trigonometric and inverse trigonometric functions, thereby ensuring the real-time performance of the algorithm. In the case of a large number of grids, a multi-level grid clustering method is adopted to further ensure the real-time performance of the algorithm.

[0059] Embodiment 1

[0060] According to a multi-level spherical grid clustering method provided by the present invention, Figure 1 As shown, including:

[0061] Grid corner point generation step: Generate M rows and N columns of grid corner points on the multi-level spherical area. That is to say, design M rows and N columns of grid corner points on the spherical area that are applicable to the following steps. In the grid corner point generation step, the N corner points in each row are on a section that contains the center of the sphere, and the M sections corresponding to the M rows intersect on the same sphere diameter. In the M sections, the distribution pattern of the N points is the same. Figure 2 As shown. The M-1 angles formed by the M sections are equal. The N-1 angles formed by the N corner points and the center of the sphere are equal; or the N-1 angles formed by the N corner points and a point S outside the sphere in the section are equal, and the distances between the S point and the first point and the Nth point in the N corner points are equal, and the distances between the S points in different sections and the center of the sphere are equal. The sphere is a celestial sphere, and the satellite orbit flies along the column direction.

[0062] The total field of view angle in the vertical track direction is determined based on the vertical track distribution range of the pixel scattered points. The angle between two adjacent corner points and the satellite is determined based on the set number of grid corner points N in the vertical track direction. All the above angles divide the total field of view angle equally. The corner point data is generated every set time interval Δt. The total field of view angle, the angles on both sides of the vertical track direction, and the number of grid corner points remain unchanged in each generation.

[0063] In the step of generating grid corner points, the total field of view angle in the vertical track direction is symmetrical along both sides of the track, and the range envelops the vertical track distribution range of pixel scatter points. The number of corner points M is an odd number, and the subsatellite point is used as the grid corner point.

[0064] Projection plane establishment step: grouping each grid corner point of the multi-level spherical area and establishing a corresponding projection plane. The projection plane establishment step includes the following sub-steps:

[0065] Step S2.1: Initialization, set i=0, M0=M.

[0066] Step S2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Group.

[0067] Step S2.3: Establish a projection plane, which passes through the center of the sphere and is perpendicular to the line connecting the center of the sphere and the center position of the corresponding grid group in the sphere. In other words, the projection plane passes through the center of the sphere and is perpendicular to the line connecting the center of the sphere and the center position of the grid in the sphere.

[0068] Step S2.4: Determine K i With M i If they are equal, then execute step S2.5. If not, then set M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point is reached, i is incremented by 1 and step S2.2 is executed.

[0069] Step S2.5: Let iMax=i, and the projection plane establishment step is completed.

[0070] The step of establishing the projection plane is to accumulate M rows of grid corner point data according to the distribution range of pixel scattered points in the along-track direction, select the grid corner point in the middle position of the M grid corner points under the satellite in the along-track direction, and make a projection plane. The plane is perpendicular to the line connecting the above-selected grid corner points and the center of the earth. A two-dimensional coordinate system is established in the above-mentioned projection plane, with the along-track direction as the Y axis and the vertical track direction as the horizontal axis X. In the step of establishing the projection plane, the projection plane passes through the center of the earth, and the normal vector points to the side with the satellite. The two-dimensional coordinate system of the projection plane uses the center of the earth as the origin, the flight direction as the Y axis, and the Y axis rotated 90° clockwise as the X axis. N is an odd number, and N rows of grid corner points envelop the distribution range of pixel scattered points in the along-track direction.

[0071] Projection clustering step: projecting the grid corner points onto the projection plane and clustering them. The projection clustering step includes the following sub-steps:

[0072] Step S3.1: Extract L iMax All rows in the hierarchy are used as projection clusters, and let i = iMax.

[0073] Step S3.2: Scatter points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and the projection grid, projection grid corner points and projection scattered points are obtained. The projection grid in step S3.2 refers to the grid in the formed projection plane. The projection grid corner points are the grid corner points projected onto the projection plane. The projection scattered points refer to the scattered points projected onto the projection plane. In the projection step, the corner points of the M rows and N columns of the grid are projected onto the projection plane. The M rows of grid corner points form (M-1)*(N-1) target grids, and the coordinates of the grid corner points in the above two-dimensional coordinate system are recorded. The pixel scattered points are projected onto the projection plane, and the coordinates of the pixel scattered points in the above two-dimensional coordinate system are recorded.

[0074] Among them, the steps for calculating the projection coordinates in the two-dimensional coordinate system are:

[0075] Step 1: In the earth-fixed coordinate system, calculate the coordinates of the unit vectors of the X-axis and Y-axis of the two-dimensional coordinate system, respectively, and record them as (x xn ,y xn ,z xn ) and (x yn ,y yn ,z yn ).

[0076] Step 2: Note that the coordinates of the point to be projected in the ground-fixed coordinate system are (x r0 ,y r0 ,z r0 ), the projection point coordinates on the projection plane (x p ,y p ) is calculated using the following formula:

[0077] xp =x r0 x xn +y r0 y xn +z r0 z xn

[0078] y p =x r0 x yn +y r0 y yn +z r0 z yn

[0079] Furthermore, the coordinates of the scattered pixel points in the above two-dimensional coordinate system are stored in an M*N two-dimensional array, and the elements of the array are structure objects that record the two-dimensional coordinates.

[0080] Step S3.3: Establish an affine auxiliary grid. In step S3.3, the row-wise side lengths of the auxiliary grid are all equal to the row-wise side lengths of the projection grid near the center of the projection grid area or equal to the row-wise side lengths of the projection grid at the corresponding position near the center line of the projection grid area. The column-wise side lengths of the auxiliary grid are all equal to the column-wise side lengths of the projection grid near the center of the projection grid area or equal to the column-wise side lengths of the projection grid at the corresponding position near the center line of the projection grid area. Specifically, an auxiliary grid is established on the projection plane. The auxiliary grid consists of M rows and N columns of grid corner points, which correspond one-to-one to the target grid and have overlapping centers. Let the generation time of the 1st row grid corner points be t1, the generation time of the Mth row grid corner points be t2, and define t m =(t1+t2) / 2. The distance between adjacent grid corner points in the Y-axis direction of the auxiliary grid is equal to t m -Δt / 2 time and t m +Δt / 2, the distance between the subsatellite point and the projection point on the projection plane is denoted as d. Generate t according to the method in the grid corner point generation step. m The corner point data at each moment is projected onto the auxiliary plane to form a point column L consisting of N points. This point column corresponds one-to-one with the corner point column of each row of the auxiliary grid, and the corresponding points have the same X coordinates. The point column L is stored in a one-dimensional array of length M. The array elements are structure objects that record one-dimensional coordinates. To compare the X coordinate values ​​in the point column L, a binary search algorithm is used.

[0081] Step S3.4: Cluster the projected scattered points to the auxiliary grid. Specifically, by calculating the ratio of the y coordinate in the projection coordinates of the pixel to d, determine which row of the grid the pixel belongs to, and by comparing the x coordinate values ​​in the point column L, determine which column the pixel is in.

[0082] Step S3.5: In the auxiliary grid, the projected scattered points are corrected to the projected grid, and the corresponding scattered points are clustered to the corresponding spherical grid. Specifically, the projection plane is divided into two parts, upper and lower, with the point sequence L as the boundary, and the steps are as follows:

[0083] Step 1: For the pixels in the upper (lower) half, find the corresponding target grid based on the auxiliary grid where it is located, and take out the coordinates of the upper (lower) corner points of the grid.

[0084] Step 2: Determine whether the pixel point is above (below) the straight line connecting the above corner points. If so, execute step 3; if not, the correction ends.

[0085] Step 3: Correct the pixels to the target grid just above (below) and return to step 1 to execute.

[0086] The step of determining whether a pixel point is above (below) the straight line connecting the corner points is as follows: Calculate A = (x0-x1)(y1-x p )-(y0-y1)(x1-x p ), where (x0, y0) and (x1, y1) are the pixel scatter points (x p ,y p ) left and right corner points. Judge A. If A is negative, (x p ,y p ) is below the line connecting (x0,y0) and (x1,y1); if positive, it is above.

[0087] Step S3.6: Determine whether i is equal to 0. If so, the projection clustering step ends. If not, execute step S3.7.

[0088] Step S3.7: Take L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1 The row corner point is used as the projection cluster for the next time, i is decremented by 1, and step S3.1 is executed.

[0089] Embodiment 2

[0090] The present invention also provides a multi-level spherical grid clustering system, which can be implemented by executing a process module of the multi-level spherical grid clustering method, that is, those skilled in the art can understand the multi-level spherical grid clustering method as a preferred implementation of the multi-level spherical grid clustering system.

[0091] A multi-level spherical grid clustering system provided by the present invention comprises:

[0092] Grid corner point generation module: Generates M rows and N columns of grid corner points on a multi-level spherical area.

[0093] Projection plane establishment module: grouping each grid corner point of the multi-level spherical area and establishing the corresponding projection plane. The projection plane establishment module includes the following submodules: Module M2.1: initialization, set i = 0, M0 = M. Module M2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Module M2.3: Establish a projection plane, which passes through the center of the sphere and is perpendicular to the line connecting the center of the sphere and the center position of the corresponding grid group in the sphere. Module M2.4: Determine K i With M i If they are equal, then trigger module M2.5. If not, then M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point is reached, i is incremented by 1, triggering module M2.2. Module M2.5: Record iMax=i, and the projection plane establishment module ends.

[0094] Projection clustering module: Project the grid corner points onto the projection plane and perform clustering. The projection clustering module includes the following submodules: Module M3.1: Extract L iMax All rows in the hierarchy are used as projected clusters, and i = iMax. Module M3.2: Scatter points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and a projection grid, projection grid corner points and projection scattered points are obtained. The projection grid described in module M3.2 refers to the grid in the formed projection plane. The projection grid corner points are the grid corner points projected onto the projection plane. The projection scattered points refer to the scattered points projected onto the projection plane. Module M3.3: Establish an affine auxiliary grid. In module M3.3, the row-direction side lengths of the auxiliary grid are all equal to the row-direction side lengths of the projection grid near the center position of the projection grid area or equal to the row-direction side lengths of the projection grid at the corresponding position near the center line of the row direction of the projection grid area. The column-direction side lengths of the auxiliary grid are all equal to the column-direction side lengths of the projection grid near the center position of the projection grid area or equal to the column-direction side lengths of the projection grid at the corresponding position near the center line of the column direction of the projection grid area. Module M3.4: Cluster the projection scattered points into the auxiliary grid. Module M3.5: In the auxiliary grid, correct the projection scattered points to the projection grid, and cluster the corresponding scattered points into the corresponding spherical grid. Module M3.6: Determine whether i is equal to 0. If so, the projection clustering module ends. If not, module M3.7 is triggered. Module M3.7: Get L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1The row corner point is used as the projection cluster for the next time, i is decremented by 1, and module M3.1 is triggered.

[0095] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0096] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A multi-level spherical grid clustering method, characterized in that: include: Grid corner point generation step: generate M rows and N columns of grid corner points on the multi-level spherical area; Projection plane establishment step: grouping each grid corner point of the multi-level spherical area and establishing a corresponding projection plane; Projection clustering step: projecting the grid corner points onto the projection plane and performing clustering.

2. The multi-level spherical grid clustering method according to claim 1, characterized in that: The projection plane establishment step includes the following sub-steps: Step S2.1: Initialization, set i=0, M0=M; Step S2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Group; Step S2.3: establishing a projection plane, wherein the projection plane passes through the center of the sphere and is perpendicular to a line connecting the center of the sphere and the center position of the corresponding grid group on the spherical surface; Step S2.4: Determine K i With M i If they are equal, then execute step S2.5; if not, then set M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point is reached, i is incremented by 1 and step S2.2 is executed; Step S2.5: Let iMax=i, and the projection plane establishment step is completed.

3. The multi-level spherical grid clustering method according to claim 1, characterized in that: The projection clustering step includes the following sub-steps: Step S3.1: Extract L iMax All rows in the hierarchy are used as projection clusters, let i = iMax; Step S3.2: Scatter points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and a projection grid, projection grid corner points and projection scattered points are obtained; Step S3.3: establishing an affine auxiliary grid; Step S3.4: clustering the projected scattered points into the auxiliary grid; Step S3.5: In the auxiliary grid, the projected scattered points are corrected to the projected grid, and the corresponding scattered points are clustered to the corresponding spherical grid; Step S3.6: Determine whether i is equal to 0. If so, the projection clustering step ends; if not, execute step S3.7; Step S3.7: Take L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1 The row corner point is used as the projection cluster for the next time, i is decremented by 1, and step S3.1 is executed.

4. The multi-level spherical grid clustering method according to claim 3, characterized in that: The projection grid in step S3.2 refers to the grid in the constructed projection plane; The projection grid corner points are grid corner points projected onto the projection plane; The projected scatter points refer to scatter points projected onto the projection plane.

5. The multi-level spherical grid clustering method according to claim 3, characterized in that: In step S3.3, the row-wise side lengths of the auxiliary grids are equal to the row-wise side lengths of the projection grids near the center of the projection grid area or equal to the row-wise side lengths of the projection grids at the corresponding positions near the row-wise center line of the projection grid area; The side lengths of the auxiliary grid columns are equal to the side lengths of the projection grid columns near the center of the projection grid area or equal to the side lengths of the projection grid columns at the corresponding positions near the center line of the projection grid area columns.

6. A multi-level spherical grid clustering system, characterized in that: include: Grid corner point generation module: generates M rows and N columns of grid corner points on a multi-level spherical area; A projection plane establishment module: groups each grid corner point of the multi-level spherical area and establishes a corresponding projection plane; Projection clustering module: projects the grid corner points onto the projection plane and performs clustering.

7. The multi-level spherical grid clustering system according to claim 1, characterized in that: The projection plane establishment module includes the following submodules: Module M2.1: Initialization, set i=0, M0=M; Module M2.2: L i Level M i Each consecutive K in the corner of the row grid i The rows are grouped into a group, totaling M i Group; Module M2.3: Establish a projection plane, which passes through the center of the sphere and is perpendicular to the line connecting the center of the sphere and the center position of the corresponding grid group on the spherical surface; Module M2.4: Determine K i With M i If they are equal, then the module M2.5 is triggered; if not, then M i The first row of the group grid is extracted as L i+1 M in the layer i+1 After the corner point, i increases by 1, triggering module M2.2; Module M2.5: Let iMax=i, and the projection plane establishment module ends.

8. The multi-level spherical grid clustering system according to claim 1, characterized in that: The projection clustering module includes the following submodules: Module M3.1: Extracting L iMax All rows in the hierarchy are used as projection clusters, let i = iMax; Module M3.2: Scatter Points and K i The row grid corner points are projected onto the projection plane to form a grid in the projection plane, and a projection grid, projection grid corner points and projection scattered points are obtained; Module M3.3: Establishing affine auxiliary grid; Module M3.4: clustering the projected scattered points into the auxiliary grid; Module M3.5: In the auxiliary grid, the projected scattered points are corrected to the projected grid, and the corresponding scattered points are clustered to the corresponding spherical grid; Module M3.6: Determine whether i is equal to 0. If so, the projection clustering module ends; if not, module M3.7 is triggered; Module M3.7: Take L i The row where the scattered point is located in the hierarchy corresponds to the row in L i-1 K in the hierarchy i-1 The row corner point is used as the projection cluster for the next time, i is decremented by 1, and module M3.1 is triggered.

9. The multi-level spherical grid clustering system according to claim 3, characterized in that: The projection grid mentioned in Module M3.2 refers to the grid in the constructed projection plane; The projection grid corner points are grid corner points projected onto the projection plane; The projected scatter points refer to scatter points projected onto the projection plane.

10. The multi-level spherical grid clustering system according to claim 3, characterized in that: The row-wise side lengths of the auxiliary grids in module M3.3 are all equal to the row-wise side lengths of the projection grids near the center of the projection grid area or equal to the row-wise side lengths of the projection grids at the corresponding positions near the row-wise center line of the projection grid area; The side lengths of the auxiliary grid columns are equal to the side lengths of the projection grid columns near the center of the projection grid area or equal to the side lengths of the projection grid columns at the corresponding positions near the center line of the projection grid area columns.

Images