Marine target data spatio-temporal index construction method based on H3 grid

Abstract

The invention relates to an ocean target data spatio-temporal index construction method based on an H3 grid. The ocean target data spatio-temporal index construction method comprises the following steps that S1, spatial mapping of data is established based on the H3 grid technology; s2, presetting a minimum time slice, and establishing time mapping of the data; and S3, establishing a spatio-temporal index based on the time mapping and the space mapping of the data. According to the method, the time dimension of the static spherical space is expanded, and the spatial-temporal continuum is discretized to form the spatial-temporal index of the layered tree structure, so that the spatial-temporal data can be uniformly identified and indexed with different granularities.

Description

Technical Field

[0001] The present invention relates to the field of geographic information technology, and in particular to a method for constructing a spatiotemporal index of ocean target data based on an H3 grid. Background Art

[0002] In order to efficiently represent and retrieve spatiotemporal information, it is necessary to discretize space and time and construct a spatiotemporal index. Traditional indexing methods are mostly spatial indexes, which do not consider the time dimension, and the discretization granularity is single, making it difficult to uniformly and efficiently represent spatiotemporal data of different levels of sophistication. At present, there is a lack of an efficient hierarchical spatiotemporal index for marine target data. The H3 grid is a hierarchical spherical spatial index that can better solve the above problems.

[0003] Therefore, designing a method to construct spatiotemporal index of ocean target data based on H3 grid is an urgent problem to be solved. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for constructing a spatiotemporal index of ocean target data based on the H3 grid, which can discretize the spatiotemporal continuum to form a spatiotemporal index with a hierarchical tree structure, realize unified identification and indexing of spatiotemporal data with different granularities, and represent spatiotemporal information with a small number of bits.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for constructing a spatiotemporal index of ocean target data based on an H3 grid, comprising the following steps:

[0006] Step S1, establishing spatial mapping of data based on H3 grid technology;

[0007] Step S2, preset the minimum time slice and establish the time mapping of data;

[0008] Step S3: establishing a spatiotemporal index based on the time mapping and space mapping of the data.

[0009] According to a technical solution of the present invention, the step S1 specifically includes:

[0010] Step S11, establishing a spherical subdivision of the earth surface based on the H3 grid;

[0011] Step S12, determining a meta-grid;

[0012] Step S13, constructing a hierarchical spatial index tree;

[0013] Step S14: Establish spatial mapping of data.

[0014] According to a technical solution of the present invention, the step S2 specifically includes:

[0015] Step S21, establishing a time axis;

[0016] Step S22, determining the minimum time slice;

[0017] Step S23, constructing a hierarchical time index tree;

[0018] Step S24: Establishing a time map of the data.

[0019] According to a technical solution of the present invention, in step S11, the WGS-84 Earth-centered Earth-fixed coordinate system is used as the reference coordinate system, and a multi-level regular hexagonal spherical mesh is formed based on a regular icosahedron as an embedded regular polyhedron of a sphere;

[0020] In the step S14, the spatial mapping of the data is to map the spatial key values ​​of the ocean target data to the spatial indexes of each level layer by layer.

[0021] According to a technical solution of the present invention, in step S12, the meta-grid is an 8.54-kilometer grid of the fifth level of the H3 grid.

[0022] According to a technical solution of the present invention, in step S21, the time axis uses the Coordinated Universal Time (UTC) as a reference time, and determines the starting time as time zero;

[0023] In the step S24, the time mapping of the data is to map the time key value of the ocean target data to the time index of each level layer by layer.

[0024] According to a technical solution of the present invention, in step S13, the hierarchical spatial index tree is established, and the 0th level has a total of 122 grids, and 7 bits are used to represent the index of each grid; each subsequent low-level grid is decomposed into 7 or 6 grids of the previous level, and 3 bits are used to represent the index of each grid; 2 bits are defaulted, and a total of 3 bytes 24 bits represent the spatial index of each meta-grid.

[0025] According to a technical solution of the present invention, in step S23, the hierarchical time index tree is a 5-level hierarchical time index tree constructed according to year, month, day, hour and minute, with the time zero point determined in step S21 as the starting point; 8 bits are used to represent the year index, 4 bits to represent the month index, 5 bits to represent the day index, 5 bits to represent the hour index, 6 bits to represent the minute index, and 4 bits are default, a total of 4 bytes 32 bits represent the time index of each minimum time slice.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention expands the time dimension of the static spherical space and discretizes the space-time continuum to form a space-time index with a hierarchical tree structure, which can realize unified identification and indexing of space-time data with different granularities.

[0028] The present invention is oriented to ocean mobile targets, and specifically selects the size of the meta-grid and the minimum time slice duration, so that the spatiotemporal information can be represented with a small number of bits.

[0029] The present invention can perform spatiotemporal discretization and indexing on the spatiotemporal data of ocean mobile targets acquired by satellites, and is suitable for constructing a spatiotemporal data structure and distributed data storage system for ocean mobile targets, and efficiently realizes distributed data storage and retrieval of original spatiotemporal data of ocean mobile targets and fused data. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A schematic diagram of a process flow of constructing a spatiotemporal index of ocean target data based on an H3 grid according to the present invention is shown schematically;

[0032] Figure 2 Schematically showing a schematic diagram of earth spherical surface partitioning based on H3 grid according to the present invention;

[0033] Figure 3 A schematic diagram of a hierarchical spatial index tree of a region according to the present invention is schematically shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figures 1 to 3 As shown, a method for constructing a spatiotemporal index of ocean target data based on an H3 grid of the present invention comprises the following steps:

[0036] Step S1, establishing spatial mapping of data based on H3 grid technology;

[0037] Step S1 specifically includes:

[0038] Step S11, establishing a spherical subdivision of the earth surface based on the H3 grid;

[0039] Taking the WGS-84 Earth-centered Earth-fixed coordinate system as the reference coordinate system, based on the regular icosahedron as the embedded regular polyhedron of the sphere, the inverse spherical center projection is performed to form the 0th level hexagonal tiling, including 110 regular hexagons and 12 regular pentagons. Subsequent fine-level multi-level grids use regular hexagonal subdivision with a subdivision aperture of 7, that is, the area of ​​each parent grid is 7 times the area of ​​its child grid, such as Figure 2 , the multi-level regular hexagonal spherical subdivision grid is formed to complete the spherical subdivision based on the H3 grid.

[0040] Step S12, determining a meta-grid;

[0041] According to the H3 grid earth spherical subdivision established in step S11, a certain level of H3 grid is selected as the most basic non-dividable element grid according to application requirements. In view of the application requirements of the satellite remote sensing field for marine target observation, considering the size of ships and the commonly used satellite width, the 8.54 km grid of the fifth level is selected as the element grid.

[0042] Step S13, constructing a hierarchical spatial index tree;

[0043] In step S13, a hierarchical spatial index tree is established. Based on the element grid determined in step S12, the element grid is tiled and stacked with an aperture of 7 to form a higher-level index, such as Figure 3 As shown. The index mapping area is based on the meta-grid stacking area, and the 4th, 3rd, and 2nd level indexes represent the shapes of the meta-grids respectively. A 6-level hierarchical spatial index tree is constructed according to levels 0 to 5. There are 122 grids in level 0, and 7 bits are used to represent the index of each grid; each subsequent low-level grid is decomposed into 7 or 6 grids of the previous level, and 3 bits are used to represent the index of each grid; 2 bits are defaulted, and a total of 3 bytes, 24 bits, represent the spatial index of each meta-grid. Each level of grid can be indexed separately, for example, only 7 bits can index the level 0 grid. A hierarchical spatial index tree is constructed based on this.

[0044] Step S14, establishing a spatial mapping of data; the spatial mapping of data is to map the spatial key values ​​of the ocean target data to spatial indexes of each level layer by layer.

[0045] Specifically, according to the spatial indexing method described in step S13, the spatial key value of the ocean target data is mapped to the spatial index of each level layer by layer, the spatial mapping of the data is completed, and the spatial index S is obtained.

[0046] Step S2, preset the minimum time slice and establish the time mapping of data;

[0047] Step S2 specifically includes:

[0048] Step S21, establishing a time axis;

[0049] In step S21, the time axis uses the Coordinated Universal Time (UTC) as a reference time, and determines the starting time, such as 00:00 on January 1, 2000, as the time zero.

[0050] Step S22, determining the minimum time slice;

[0051] Specifically, according to the time axis established in step S21, a certain shortest time period is selected as the minimum time slice according to application requirements. In view of the application requirements of the satellite remote sensing field for marine target observation, considering the speed of the ship, 1 minute is selected as the minimum time slice.

[0052] Step S23, constructing a hierarchical time index tree;

[0053] In step S23, the hierarchical time index tree is a 5-level hierarchical time index tree constructed according to the minimum time slice determined in step S22, that is, a 1-minute time slice, with the time zero point determined in step S21 as the starting point, and according to year, month, day, hour, and minute; 8 bits are used to represent the year index, 4 bits to represent the month index, 5 bits to represent the day index, 5 bits to represent the hour index, 6 bits to represent the minute index, and 4 bits are default, a total of 4 bytes 32 bits represent the time index of each minimum time slice. Each level of time can be indexed separately, for example, only 8 bits can index a certain year time. A hierarchical time index tree is constructed accordingly.

[0054] Step S24, establishing a time mapping of the data; the time mapping of the data is to map the time key value of the ocean target data to the time index of each level layer by layer.

[0055] According to the time indexing method described in step S23, the time key value of the ocean target data is mapped to the time index of each level layer by layer, the time mapping of the data is completed, and the time index T is obtained.

[0056] Step S3: Establish a spatiotemporal index based on the time mapping and space mapping of the data.

[0057] Combine the spatial index S and the temporal index T to form a spatiotemporal index tuple (S, T).

[0058] The present invention discretizes the space-time continuum to form a space-time index with a hierarchical tree structure, realizes unified identification and indexing of space-time data with different granularities, and can represent space-time information with a small number of bits.

[0059] In summary, the spatiotemporal indexing method of marine target data based on H3 grid of the present invention first defines a certain level of H3 grid that meets the application needs as the basic element grid, then forms a hierarchical index structure according to hexagonal tiling and nesting, defines grid coding, constructs a hierarchical spatial index tree and establishes a spatial mapping of data to obtain a spatial index S. A time axis is established with UTC time, and after the minimum time slice is determined according to the application requirements, a hierarchical time index tree is constructed and a time mapping of the data is established to obtain a time index T. Combine the spatial index S and the time index T to form a spatiotemporal index tuple (S, T). The present invention can discretize the spatiotemporal continuum to form a spatiotemporal index of a hierarchical tree structure, realize unified identification indexing of spatiotemporal data with different granularities, and characterize spatiotemporal information with a small number of bits.

[0060] Parts of the present invention that are not described in detail belong to the well-known technology in the art.

[0061] It should be noted that although the embodiments of the present invention described above are illustrative, they are not intended to limit the present invention, and therefore the present invention is not limited to the above specific embodiments. Without departing from the principles of the present invention, any other embodiments obtained by those skilled in the art under the guidance of the present invention are deemed to be within the protection of the present invention.

Claims

1. A method for constructing a spatiotemporal index of ocean target data based on H3 grid, characterized in that: The following steps are involved: Step S1, establishing spatial mapping of data based on H3 grid technology; Step S2, preset the minimum time slice and establish the time mapping of data; Step S3: establishing a spatiotemporal index based on the time mapping and space mapping of the data.

2. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 1, characterized in that: The step S1 specifically includes: Step S11, establishing a spherical subdivision of the earth surface based on the H3 grid; Step S12, determining a meta-grid; Step S13, constructing a hierarchical spatial index tree; Step S14: Establish spatial mapping of data.

3. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 2, characterized in that: The step S2 specifically includes: Step S21, establishing a time axis; Step S22, determining the minimum time slice; Step S23, constructing a hierarchical time index tree; Step S24: Establishing a time map of the data.

4. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 2, characterized in that: In the step S11, the WGS-84 Earth-centered Earth-fixed coordinate system is used as the reference coordinate system, and a multi-level regular hexagonal spherical mesh is formed based on the regular icosahedron as an embedded regular polyhedron of the sphere; In the step S14, the spatial mapping of the data is to map the spatial key values ​​of the ocean target data to the spatial indexes of each level layer by layer.

5. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 2, characterized in that: In the step S12, the meta-grid is an 8.54-kilometer grid at the fifth level of the H3 grid.

6. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 3, characterized in that: In step S21, the time axis uses the Coordinated Universal Time (UTC) as a reference time, and determines the starting time as time zero; In step S24, the time mapping of the data is to map the time key value of the ocean target data to the time index of each level layer by layer.

7. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 2, characterized in that: In step S13, the hierarchical spatial index tree is established. The 0th level has a total of 122 grids, and 7 bits are used to represent the index of each grid; each subsequent low-level grid is decomposed into 7 or 6 grids of the previous level, and 3 bits are used to represent the index of each grid; 2 bits are defaulted, and a total of 3 bytes 24 bits represent the spatial index of each meta-grid.

8. The method for constructing a spatiotemporal index of ocean target data based on an H3 grid according to claim 6, characterized in that: In step S23, the hierarchical time index tree is a 5-level hierarchical time index tree constructed according to year, month, day, hour and minute, with the time zero point determined in step S21 as the starting point; 8 bits are used to represent the year index, 4 bits to represent the month index, 5 bits to represent the day index, 5 bits to represent the hour index, 6 bits to represent the minute index, and 4 bits are default, with a total of 4 bytes and 32 bits representing the time index of each minimum time slice.

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