A large-scene electronic map visualization method and device, a terminal and a medium

Abstract

The application discloses a large-scene electronic map visualization method and device, a terminal and a medium. The method obtains a geographic database and a mapping expression of a vector map. When any geographic entity of the geographic database crosses two or more vector tiles, according to a preset conversion definition of a geographic feature space and the mapping expression, tile data models of corresponding point, line and surface features are used for rendering to obtain a vector tile electronic map. An improved Geohash coding mode is used for coding conversion to obtain a visualized electronic map. Therefore, the embodiment of the application can distinguish geographic entities and divide geographic entity features in a graphical matching manner, thereby solving the visual discontinuity problem of vector tiles at tile boundaries in the prior art. Moreover, the improved Geohash coding mode can simultaneously reflect the position and size features of a two-dimensional space target, improve the spatial index efficiency, and thus improve the transmission performance and readability of data in a large scene.

Description

Technical Field

[0001] This invention relates to the field of electronic map technology, and in particular to a method, device, terminal and medium for visualizing electronic maps in large-scale scenarios. Background Technology

[0002] Traditional electronic maps are based on Web Map Services (WMS). However, the unrestricted spatial parameters during image generation by WMS servers lead to latency. Furthermore, the lack of caching capabilities prevents WMS from handling concurrent users. Currently, the "pyramid technique" is popular, using raster data to improve transmission performance. Combined with WMS technology, this forms a Web Map Tile Service (WMTS), where the map is divided into tiles for transmission to the client. However, this method loses the interactivity of vector maps. Any modifications to the electronic map require regenerating and transmitting tiles, which undoubtedly increases time costs, especially for massive datasets in large-scale scenarios. Moreover, in the visualization process of vector electronic maps, to reduce the amount of data transmitted, the vector map is divided into two datasets for transmission: a database and a cartographic representation. Only the database is transmitted, while the cartographic representation is performed locally on the client. However, when a geographic entity spans two vector tiles, this method can create visual discontinuities or even conflicts at the tile boundaries. Furthermore, due to the large volume of vector data, data compression is generally used to improve transmission efficiency during transmission. However, existing data compression methods can affect visualization effects. Additionally, the massive data volume can place a significant burden on the client side when rendering vector tile electronic maps in large-scale scenes. Solving the problem of visual discontinuities at tile boundaries in existing vector tile technologies, as well as the trade-off between data transmission efficiency and visualization effects in large-scale scenes, presents a considerable challenge. Summary of the Invention

[0003] This invention provides a method, apparatus, terminal, and device for visualizing electronic maps in large-scale scenes. It can solve the problem of visual discontinuity at the boundaries of vector tiles in the prior art, as well as the problem that data transmission efficiency and visualization effect cannot be balanced in large-scale scenes, thereby improving the data transmission performance and readability in large-scale scenes.

[0004] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a method for visualizing electronic maps in large-scale scenarios, including:

[0005] Obtain the geographic database and cartographic representation of vector maps;

[0006] When any geographic entity in the geographic database spans two or more vector tiles, the corresponding point, line, and area feature tile data model is used for rendering according to the preset transformation definition of geographic feature space and cartographic representation, to obtain a vector tile electronic map.

[0007] The vector tile electronic map is encoded and converted using an improved Geohash encoding method to obtain a visualized electronic map;

[0008] The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators, which include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features; the rules for using the feature operators include the following definitions;

[0009] Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear features and their ends are connected or their styles are the same; both geographic features are area features and they are intersecting, connected, or contained with each other.

[0010] Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated;

[0011] Definition 3: The prerequisite for using the addition operator of the map features is that the two geographic features have the same style and corresponding style parameters. Through style conversion, map features can be obtained. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1.

[0012] Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant;

[0013] Definition 5: The top left vertex of the bounding rectangle of the surface feature is the starting point of the surface feature pattern;

[0014] Definition 6: The prerequisite for using the addition operator for isometric map features is that two isometric map features are obtained by performing the style transformation on two corresponding isometric geographic features. The style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the x-coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, and the absolute value of the difference between the y-coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths. The two isometric geographic features satisfy Definition 1.

[0015] Furthermore, the process of encoding and converting the vector tile electronic map using an improved Geohash encoding method to obtain a visualized electronic map specifically includes:

[0016] Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map;

[0017] Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle;

[0018] By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained.

[0019] The new encoding is converted to obtain a visualized electronic map.

[0020] Furthermore, by combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is determined, and a new code for the vector tile electronic map is derived, specifically including:

[0021] By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map.

[0022] Wherein, the level expression is

[0023]

[0024] In the formula, level represents the current level of the vector tile electronic map, level = 0 represents the initial level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

[0025] Specifically, the formula for calculating the centroid coordinates is as follows:

[0026]

[0027] In the formula, x0 is the abscissa of the centroid of the vector tile electronic map, y0 is the ordinate of the centroid of the vector tile electronic map, xmax and xmin are the maximum and minimum x-axis coordinates of the minimum bounding rectangle, and ymax and ymin are the maximum and minimum y-axis coordinates of the minimum bounding rectangle.

[0028] Secondly, embodiments of the present invention provide an electronic map visualization device for large-scale scenarios, comprising:

[0029] The acquisition module is used to acquire the geographic database and cartographic representation of the vector map;

[0030] The rendering module is used to render a vector tile electronic map by using the corresponding point, line, and area tile data model according to the preset transformation definition of geographic feature space and cartographic expression when any geographic entity in the geographic database spans two or more vector tiles.

[0031] The conversion module is used to encode and convert the vector tile electronic map using an improved Geohash encoding method to obtain a visualized electronic map;

[0032] The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators, which include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features; the rules for using the feature operators include the following definitions;

[0033] Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear features and their ends are connected or their styles are the same; both geographic features are area features and they are intersecting, connected, or contained with each other.

[0034] Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated;

[0035] Definition 3: The prerequisite for using the addition operator of the map features is that the two geographic features have the same style and corresponding style parameters. Through style conversion, map features can be obtained. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1.

[0036] Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant;

[0037] Definition 5: The top left vertex of the bounding rectangle of the surface feature is the starting point of the surface feature pattern;

[0038] Definition 6: The prerequisite for using the addition operator for isometric map features is that two isometric map features are obtained by performing the style transformation on two corresponding isometric geographic features. The style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the x-coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, and the absolute value of the difference between the y-coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths. The two isometric geographic features satisfy Definition 1.

[0039] Furthermore, the conversion module is specifically used for:

[0040] Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map;

[0041] Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle;

[0042] By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained.

[0043] The new encoding is converted to obtain a visualized electronic map.

[0044] Furthermore, by combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is determined, and a new code for the vector tile electronic map is derived, specifically including:

[0045] By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map.

[0046] Wherein, the level expression is

[0047]

[0048] In the formula, level represents the current level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

[0049] Specifically, the formula for calculating the centroid coordinates is as follows:

[0050]

[0051] In the formula, x0 is the abscissa of the centroid of the vector tile electronic map, y0 is the ordinate of the centroid of the vector tile electronic map, xmax and xmin are the maximum and minimum x-axis coordinates of the minimum bounding rectangle, and ymax and ymin are the maximum and minimum y-axis coordinates of the minimum bounding rectangle.

[0052] Thirdly, the present invention provides a terminal device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the above-mentioned large-scale electronic map visualization method.

[0053] Furthermore, embodiments of the present invention also provide a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the above-mentioned large-scale electronic map visualization method.

[0054] Compared with existing technologies, the present invention discloses a method, device, terminal, and medium for visualizing electronic maps in large-scale scenes. By acquiring a geographic database and cartographic representation of a vector map, when any geographic entity in the geographic database spans two or more vector tiles, it renders a vector tile electronic map using a tile data model with corresponding point, line, and area features according to a preset conversion definition of geographic feature space and cartographic representation. An improved Geohash encoding method is then used to encode and convert the vector tile electronic map, resulting in a visualized electronic map. Therefore, the present invention can distinguish geographic entities and classify geographic entity features through graphic matching, thereby solving the problem of visual discontinuity at tile boundaries in existing technologies. Furthermore, the improved Geohash encoding method can simultaneously reflect the location and size characteristics of two-dimensional spatial targets, improving spatial indexing efficiency. This solves the problem of balancing data transmission efficiency and visualization effects in large-scale scenes, improving data transmission performance and readability in large-scale scenarios. Attached Figure Description

[0055] Figure 1 This is a flowchart illustrating a method for visualizing electronic maps in a large-scale scenario, provided by an embodiment of the present invention.

[0056] Figure 2 This is a schematic diagram of the structure of an electronic map visualization device for large-scale scenarios provided in an embodiment of the present invention;

[0057] Figure 3 Example diagram of the addition operator for geographical features;

[0058] Figure 4 Example diagram of the accumulation operator for geographical features;

[0059] Figure 5 Example diagram of the addition operator for map features;

[0060] Figure 6 Example diagram of linear features;

[0061] Figure 7 A schematic diagram of linear feature tile matching in a traditional model;

[0062] Figure 8 A schematic diagram of the linear features rendered from the optimized linear feature tile data model;

[0063] Figure 9 Example diagram of the starting point for a custom style of a planar feature;

[0064] Figure 10 Example diagrams that do not satisfy definition 6;

[0065] Figure 11 Example diagrams that satisfy Definition 6. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] It should be noted that the terms "comprising" and "specific" in this invention, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0068] It should be noted that electronic map styles are divided into three types: points, lines, and polygons. The representation of lines is relatively complex. Any style in the style library Q of the cartographic representation is composed of geometric shapes, and its attributes include color and line width. The bounding polygon of a style is represented by a rectangle, the width of which is the width of the style, and the length of which is the length of the style. The style parameter λ is represented as follows:

[0069]

[0070] When the style is line-shaped, the style parameter λ represents the length l of the line-shaped style; when the style is area-shaped, the style parameter λ represents the width w and length l of the area-shaped style.

[0071] Geographic feature space is a spatial abstraction of geographic entities in the real world, and geographic feature space can be converted into map feature space, which is what we commonly call an electronic map, through style representation. This conversion process can be described by the following formula:

[0072] M = S(G, Q)

[0073] Where M represents the map feature space, G represents the geographic feature space, Q represents the style library corresponding to the geographic feature space G, and S represents the common style function of the geographic feature space. The transformation process of a single map feature in the map feature space can be represented as follows:

[0074] m = S(g,q) (m∈M,g∈G,q∈Q)

[0075] Where m, g, and q represent individual features or styles in the conversion process.

[0076] In existing technologies, when vector tiles are rendered, map features within a single tile are easily rendered. However, when geographic features span different tiles, and each tile performs style transformation on the features cut from its own tile and connects them to the corresponding tile, the map features cannot be well matched at the tile boundaries.

[0077] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for visualizing electronic maps in large-scale scenes according to an embodiment of the present invention. The method includes steps S11 to S13:

[0078] S11: Obtain the geographic database and cartographic representation of the vector map;

[0079] S12: When any geographic entity in the geographic database spans two or more vector tiles, the corresponding point, line, and area feature tile data model is used for rendering according to the preset transformation definition of geographic feature space and cartographic expression to obtain a vector tile electronic map.

[0080] S13: The vector tile electronic map is encoded and converted using an improved Geohash encoding method to obtain a visualized electronic map;

[0081] The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators, which include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features; the rules for using the feature operators include the following definitions;

[0082] Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear features and their ends are connected or their styles are the same; both geographic features are area features and they are intersecting, connected, or contained with each other.

[0083] Example, This indicates the connection between two features. This indicates that two map features are connected. This indicates the connection between two geographic features.

[0084] Addition operators for geographical features Prerequisites for use: (1) g1 and g2 are both linear features and their tails are connected or g1 = g2; (2) g1 and g2 are both planar features and they are intersecting, connected or contained.

[0085] Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated;

[0086] For example, the accumulation operator for geographic features is defined as follows: Specifically, Where g i ∈G, n≥1, and where g1·g2…g n All conform to Definition 1.

[0087] It should be noted that the addition and accumulation operators here are similar to the definitions of "+" and "∑" in regular mathematical operations. Figure 3 In the examples (a), (d), and (e), the conditions for the "addition" of geographical features are met. Figure 4 In the diagram, g is a linear pattern, and the linear feature AB is composed of 6 of these patterns. This linear feature can be represented as... This form is somewhat redundant, so we simplify it using an accumulation operator, resulting in:

[0088] Definition 3: The prerequisite for using the addition operator of the map features is that the two geographic features have the same style and corresponding style parameters. Through style conversion, map features can be obtained. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1.

[0089] Example: Addition operator for map features Prerequisites for use: Geographic features g1 and g2 have the same style q and corresponding style parameter λ. Through style transformation, map features m1 = S(g1, q) and m2 = S(g2, q) can be obtained. When geographic feature g1 can be divided into n components by the style parameter ( (where n is an integer) and g1 and g2 satisfy Definition 1,

[0090] like Figure 5 As shown, Figure 5 In (a), m1 = S(g1, q) and m2 = S(g2, q) do not satisfy the definition of the "addition" operator for map features because g1 cannot be divided into n parts by style q. Figure 5 The example in (b) satisfies the definition of the "addition" operator for map features.

[0091] Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant;

[0092] For example, for any feature φ (φ∈M||φ∈G), then

[0093] by Figure 6 Taking linear features as an example, a railway geographical feature g is divided into g1 and g2 by tiles T1 and T2, therefore we can obtain The corresponding map feature m can be represented as m = S(g, q), and the map features m1 and m2 corresponding to geographic features g1 and g2 are represented by the formulas m1 = S(g1, q) and m2 = S(g2, q). If Then the tile boundaries will not be deformed or discontinuous, such as Figure 5 As shown, since neither g1 nor g2 can be integerized by the style parameter, the feature separated by the tiles is set as... Divided into Δg1 and Δg2 by the tile boundary, and Δg1 and Δg2 located in different tiles, the feature g can be expressed as: in Since g1 cannot be integerized by style q, therefore It does not satisfy definition three, that is Therefore, g1 and g2 cannot match at the tile boundary, such as Figure 7 As shown.

[0094] Definition 5: The top left vertex of the bounding rectangle of the surface feature is the starting point of the surface feature pattern;

[0095] like Figure 9 As shown, the surface feature g is a polygon ABCDE, and the upper left vertex P of its circumscribed rectangle is called the style starting point of the surface feature g.

[0096] Definition 6: The prerequisite for using the addition operator for isometric map features is that two isometric map features are obtained by performing the style transformation on two corresponding isometric geographic features. The style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the x-coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, and the absolute value of the difference between the y-coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths. The two isometric geographic features satisfy Definition 1.

[0097] For example, the prerequisites for using the feature addition operator for polygon maps are: polygon features m1 = S(g1, q), m2 = S(g2, q), the style starting points of g1 and g2 are P1(x1, y1) and P2(x2, y2) respectively, and the polygon features g1 and g2 have the same style q, and the corresponding style parameter λ contains the same style width w and style length l. In addition, m1 and m2 can be perfectly matched and must also meet the following conditions: (1) |x1-x2| = k × w (k is an integer), (2) |y1-y2| = n × l (l is an integer), (3) g1 and g2 satisfy definition one. When the above requirements are met,

[0098] like Figure 10 As shown (where (a) represents the geographic features of g1 and g2, (b) represents the style q of g1 and g2, (c) represents the map features of g1, (d) represents the map features of g2, and (e) represents the map features of g2),... Besides conditions (1) and (2), g1 and g2 also satisfy other conditions, as can be seen from the figure. and They are not equal. Figure 11 In the diagram (where (a) represents the geographical features of g1 and g2, (b) represents the style q of g1 and g2, (c) represents the map features of g1, (d) represents the map features of g2, and (e) represents the map features of g2. as well as g1 and g2 satisfy all the conditions in Definition 6, which shows that

[0099] It should be noted that the preset linear feature tile data model is as follows:

[0100]

[0101] Many features encounter this problem. To better match map features at the edges, the model was optimized, as follows, corresponding to... Figure 8 The three situations, among which

[0102] by Figure 6 Taking the linear features in the text as an example,

[0103] and then,

[0104]

[0105] After simplification according to Definitions 3 and 4:

[0106]

[0107] You can get Therefore, this method solves the problem of tile edge conflict.

[0108] The preset tile data model with point features is

[0109]

[0110] Where σ is the extended feature and σ = g, in case (a), if the tile includes the point feature, then the point feature is directly added to the tile feature set. In case (b), if the tile does not include the point feature but the point's map feature intersects with the tile, then the point feature is also directly added to the tile feature set. In case (c), when the point's map feature does not intersect with the tile, the point feature is skipped.

[0111] Specifically, step S13 includes:

[0112] Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map;

[0113] Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle;

[0114] By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained.

[0115] The new encoding is converted to obtain a visualized electronic map.

[0116] It should be noted that during the loading of vector electronic maps in large-scale scenarios, changes in scale may lead to data overload and consequently poor visualization. To improve the efficiency of querying massive vector data, numerous spatial indexing techniques have been researched in the existing field. However, for loading large-scale dynamic data, existing spatial indexing techniques suffer from problems such as low retrieval efficiency, complex structures, and data redundancy.

[0117] Geohash is a geocoding technique based on geodetic coordinates. It uses strings to represent the location of spatial point objects. It continuously squares the global space and uses 0 and 1 as two-part spatial codes to gradually narrow the spatial range to the target point. It converts latitude and longitude coordinates into one-dimensional strings, then merges the latitude and longitude sequences, where the odd-numbered sequences are the longitude sequences and the even-numbered sequences are the latitude sequences. Finally, it is encoded based on Base32 and converted into a decimal sequence.

[0118] For point objects, Geohash encoding can be used directly. For line and area objects, Geohash encoding is typically performed on the top-left and top-right corners of the smallest bounding rectangle of the line or area object. The longest matching prefix among the two encodings is used as the Geohash code for the object. However, when the line or area object crosses a low-level Geohash grid, the matching prefix may be too short, making it difficult to locate the object effectively. For example, if the endpoints of a line segment are (-0.0001°, -0.0001°) and (0.000°, 0.0001°), and the line segment is only a few tens of meters long, the Geohash codes for the two endpoints are 7zzzzzzzmtm7 and s0000000d6ds, which have no common prefix. To improve the application range of Geohash encoding, it has been improved.

[0119] Specifically, a curve that can fill the entire grid is generated recursively. This curve first passes through each grid, but only once, and each grid is linearly ordered and encoded. This encoding serves as the unique identifier of the grid. The object's centroid latitude and longitude are used for encoding, combined with subdivision level information, to improve spatial indexing efficiency and expand the application scope of Geohash.

[0120] Furthermore, by combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is determined, and thus a new code for the vector tile electronic map is derived, specifically including:

[0121] By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map.

[0122] Wherein, the level expression is

[0123]

[0124] In the formula, level represents the current level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

[0125] It should be noted that the initial level of the vector tile electronic map is defined as level = 0, and the calculation... If the condition is not met, increment the level by 1 until the above formula is satisfied, and then obtain the level information.

[0126] Based on the improved Geohash algorithm, the new encoding of the vector tile electronic map can be obtained as (x0, y0, level).

[0127] Specifically, the formula for calculating the centroid coordinates is as follows:

[0128]

[0129] In the formula, x0 is the abscissa of the centroid of the vector tile electronic map, y0 is the ordinate of the centroid of the vector tile electronic map, xmax and xmin are the maximum and minimum x-axis coordinates of the minimum bounding rectangle, and ymax and ymin are the maximum and minimum y-axis coordinates of the minimum bounding rectangle.

[0130] Figure 2 This is a schematic diagram of the structure of a large-scene electronic map visualization device provided in an embodiment of the present invention. The large-scene electronic map visualization device includes:

[0131] Module 21 is used to acquire the geographic database and cartographic representation of the vector map;

[0132] Rendering module 22 is used to render a vector tile electronic map by using the corresponding point, line, and area tile data model according to the preset transformation definition of geographic feature space and cartographic expression when any geographic entity in the geographic database spans two or more vector tiles.

[0133] The conversion module 23 is used to encode and convert the vector tile electronic map using an improved Geohash encoding method to obtain a visualized electronic map;

[0134] The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators, which include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features; the rules for using the feature operators include the following definitions;

[0135] Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear features and their ends are connected or their styles are the same; both geographic features are area features and they are intersecting, connected, or contained with each other.

[0136] Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated;

[0137] Definition 3: The prerequisite for using the addition operator of the map features is that the two geographic features have the same style and corresponding style parameters. Through style conversion, map features can be obtained. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1.

[0138] Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant;

[0139] Definition 5: The top left vertex of the bounding rectangle of the surface feature is the starting point of the surface feature pattern;

[0140] Definition 6: The prerequisite for using the addition operator for isometric map features is that two isometric map features are obtained by performing the style transformation on two corresponding isometric geographic features. The style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the x-coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, and the absolute value of the difference between the y-coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths. The two isometric geographic features satisfy Definition 1.

[0141] In a preferred embodiment, the conversion module 23 is specifically used for:

[0142] Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map;

[0143] Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle;

[0144] By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained.

[0145] The new encoding is converted to obtain a visualized electronic map.

[0146] Furthermore, by combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is determined, and thus a new code for the vector tile electronic map is derived, specifically including:

[0147] By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map.

[0148] Wherein, the level expression is

[0149]

[0150] In the formula, level represents the current level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

[0151] Specifically, the formula for calculating the centroid coordinates is as follows:

[0152]

[0153] In the formula, x0 is the abscissa of the centroid of the vector tile electronic map, y0 is the ordinate of the centroid of the vector tile electronic map, xmax and xmin are the maximum and minimum x-axis coordinates of the minimum bounding rectangle, and ymax and ymin are the maximum and minimum y-axis coordinates of the minimum bounding rectangle.

[0154] The electronic map visualization device for large scenes provided in this embodiment of the invention can realize all the processes of the electronic map visualization method for large scenes in the above embodiments. The functions and technical effects of each module in the device are the same as the functions and technical effects of the electronic map visualization method for large scenes in the above embodiments, and will not be repeated here.

[0155] This invention provides a terminal device comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps described in the above-described embodiment of the electronic map visualization method for large-scale scenes. Alternatively, when the processor executes the computer program, it implements the functions of each module described in the above-described embodiment of the electronic map visualization device for large-scale scenes.

[0156] The terminal device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the schematic diagram is merely an example of a terminal device and does not constitute a limitation on the terminal device. It may include more or fewer components than illustrated, or combine certain components, or different components. For example, the terminal device may also include input / output devices, network access devices, buses, etc.

[0157] The processor can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field-programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting various parts of the terminal device via various interfaces and lines.

[0158] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, phonebook, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart memory card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0159] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0160] This invention also provides a computer-readable storage medium, which includes a stored computer program, wherein the computer program, when running, controls the device where the computer-readable storage medium is located to execute the large-scale electronic map visualization method as described in the above embodiments.

[0161] In summary, the present invention discloses a method, apparatus, terminal, and medium for visualizing electronic maps in large-scale scenes. By acquiring a geographic database and cartographic representation of a vector map, when any geographic entity in the geographic database spans two or more vector tiles, the system renders a vector tile electronic map using a tile data model with corresponding point, line, and area features based on a preset conversion definition of geographic feature space and cartographic representation. An improved Geohash encoding method is then used to encode and convert the vector tile electronic map, resulting in a visualized electronic map. Therefore, the present invention can distinguish geographic entities and classify geographic entity features using graphic matching, thereby solving the problem of visual discontinuity at tile boundaries in existing technologies. Furthermore, the improved Geohash encoding method can simultaneously reflect the location and size characteristics of two-dimensional spatial targets, improving spatial indexing efficiency. This addresses the issue of balancing data transmission efficiency and visualization effects in large-scale scenes, improving data transmission performance and readability in such scenarios.

[0162] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for visualizing electronic maps in large-scale scenarios, characterized in that, include: Obtain the geographic database and cartographic representation of vector maps; When any geographic entity in the geographic database spans two or more vector tiles, if it is a point geographic feature, the corresponding point geographic feature tile data model is used for rendering; if it is a line or area geographic feature, the corresponding line or area geographic feature tile data model is used for rendering according to the preset geographic feature space and cartographic representation conversion definition to obtain a vector tile electronic map. The vector tile electronic map is encoded and converted using an improved Geohash encoding method to obtain a visualized electronic map; The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators. These feature operators include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features. The rules for using these feature operators include the following definitions: Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear geographic features and their ends are connected or their styles are the same; both geographic features are area geographic features and they are intersecting, connected, or contained with each other. Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated; Definition 3: The prerequisite for using the addition operator of the map features is that the geographic features corresponding to the two map features have the same style and corresponding style parameters. The map features can be obtained through style conversion. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1. Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant; Definition 5: The upper left vertex of the bounding rectangle of the isometric geographic feature is the starting point of the isometric geographic feature pattern; Definition 6: The prerequisite for using the addition operator of the isometric map features is that two isometric map features are obtained by style transformation through two corresponding isometric geographic features, the style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the horizontal coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, the absolute value of the difference between the vertical coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths, and the two isometric geographic features satisfy Definition 1.

2. The method for visualizing electronic maps in large-scale scenarios as described in claim 1, characterized in that, The process of encoding and converting the vector tile electronic map using an improved Geohash encoding method to obtain a visualized electronic map specifically includes: Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map; Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle; By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained. The new encoding is converted to obtain a visualized electronic map.

3. The method for visualizing electronic maps in large-scale scenarios as described in claim 2, characterized in that, The level of the vector tile electronic map is determined by combining the level information and the span of the minimum bounding rectangle, and then a new code for the vector tile electronic map is derived, specifically including: By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map. Wherein, the level expression is ， In the formula, level represents the current level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

4. The method for visualizing electronic maps in large-scale scenarios as described in claim 2, characterized in that, The formula for calculating the centroid coordinates is: ( )=（ ）， In the formula, Let x be the centroid x-coordinate of the vector tile electronic map. The centroid ordinate of the vector tile electronic map is given. Let x be the maximum and minimum x-axis coordinates of the minimum bounding rectangle. The maximum and minimum values ​​of the y-axis coordinates of the minimum bounding rectangle are given.

5. A large-scale electronic map visualization device, characterized in that, include: The acquisition module is used to acquire the geographic database and cartographic representation of the vector map; The rendering module is used to render a vector tile electronic map when any geographic entity in the geographic database spans two or more vector tiles. If the geographic entity is a point geographic feature, the corresponding point geographic feature tile data model is used for rendering; if the geographic entity is a line or area geographic feature, the corresponding line or area geographic feature tile data model is used for rendering according to the preset conversion definition of geographic feature space and cartographic expression. The conversion module is used to encode and convert the vector tile electronic map using an improved Geohash encoding method to obtain a visualized electronic map; The preset definition of the transformation between geographic feature space and cartographic representation is improved by constructing additivity feature operators. These feature operators include a connector for connecting two features, a symbol for connecting two map features, and a symbol for connecting two geographic features. The rules for using these feature operators include the following definitions: Definition 1: The prerequisite for using the addition operator of the geographic features is that both geographic features are linear geographic features and their ends are connected or their styles are the same; both geographic features are area geographic features and they are intersecting, connected, or contained with each other. Definition 2: When the geographic features meet the criteria of Definition 1 and there are two or more of them, they are accumulated; Definition 3: The prerequisite for using the addition operator of the map features is that the geographic features corresponding to the two map features have the same style and corresponding style parameters. The map features can be obtained through style conversion. At the same time, any one of the geographic features can be divided into n components by the style parameters, where n is an integer, and both geographic features satisfy Definition 1. Definition 4: The addition operators of the geographic features and the addition operators of the map features are invariant; Definition 5: The upper left vertex of the bounding rectangle of the isometric geographic feature is the starting point of the isometric geographic feature pattern; Definition 6: The prerequisite for using the addition operator of the isometric map features is that two isometric map features are obtained by style transformation through two corresponding isometric geographic features, the style starting points of the two isometric geographic features satisfy Definition 5, and the two isometric geographic features have the same style and the style parameters include the same style width and style length. At the same time, the absolute value of the difference between the horizontal coordinates of the style starting points of the two isometric geographic features is equal to the product of k style widths, the absolute value of the difference between the vertical coordinates of the style starting points of the two isometric geographic features is equal to the product of j style lengths, and the two isometric geographic features satisfy Definition 1.

6. The large-scale electronic map visualization device as described in claim 5, characterized in that, The conversion module is specifically used for: Obtain the latitude and longitude information of the minimum bounding rectangle of the vector tile electronic map; Calculate the centroid coordinates of the vector tile electronic map to obtain the length and width distance of the minimum bounding rectangle, thereby obtaining the span of the minimum bounding rectangle; By combining the level information and the span of the minimum bounding rectangle, the level of the vector tile electronic map is obtained, and then a new code for the vector tile electronic map is obtained. The new encoding is converted to obtain a visualized electronic map.

7. The large-scale electronic map visualization device as described in claim 6, characterized in that, The level of the vector tile electronic map is determined by combining the level information and the span of the minimum bounding rectangle, and then a new code for the vector tile electronic map is derived, specifically including: By combining the level information and the span of the minimum bounding rectangle, the current level of the vector tile electronic map is increased one by one until the level expression is satisfied, thus obtaining the level of the vector tile electronic map and a new code for the vector tile electronic map. Wherein, the level expression is ， In the formula, level represents the current level of the vector tile electronic map, and s represents the span of the minimum bounding rectangle.

8. The large-scale electronic map visualization device as described in claim 6, characterized in that, The formula for calculating the centroid coordinates is: ( )=（ ）， In the formula, Let x be the centroid x-coordinate of the vector tile electronic map. The centroid ordinate of the vector tile electronic map is given. Let x be the maximum and minimum x-axis coordinates of the minimum bounding rectangle. The maximum and minimum values ​​of the y-axis coordinates of the minimum bounding rectangle are given.

9. A terminal device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the large-scene electronic map visualization method as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform the large-scene electronic map visualization method as described in any one of claims 1-4.

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