CN116737852A - Vector tile data-based vector drawing method and device and electronic equipment - Google Patents
Vector tile data-based vector drawing method and device and electronic equipment Download PDFInfo
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Abstract
The application discloses a vector drawing method and device based on vector tile data and electronic equipment, wherein the method comprises the following steps: calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a downloading request link, and obtaining vector tile data; creating vector tile objects using vector tile data based on the defined vector tile data format; comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data, and displaying the vector map. In the application, a vector tile file structure with a spatial range, projection information, element attributes and rendering styles is provided; the vector tiles are rapidly loaded through the index occupying information, and file decoding links are removed.
Description
Technical Field
The present application relates to the field of geographic information systems, and in particular, to a vector drawing method, apparatus and electronic device based on vector tile data.
Background
Geographic Information Systems (GISs) are becoming key support technologies for network information platforms such as digital earth, digital cities, navigation and positioning, and as a core resource of GISs, vector map applications are becoming more and more widespread, and even are the necessary basic data on which many network information platforms depend. In order to meet the high-quality requirements of people for map drawing in a network environment, a tile technology is generally adopted, firstly, vector data are rendered into grid tiles at a server end, then a client end requests pictures to be displayed, the method has the defects of large data size, distortion in zooming and incapability of freely configuring display modes, secondly, the server end provides vector tile data, the client end requests the vector data and then automatically renders and displays, and because vector data are used in the vector tiles to describe map elements, a map is formed by rendering the vector data, the data size is small, the map is not distorted in zooming, the display can be performed at different visual angles, and the requirements of people for real-time drawing of the vector map are well met.
The vector tile commonly used at present is a 'Mapbox MVT' data standard, and is encoded by adopting 'Google Protocol Buffers', so that the vector tile data encoding format capable of saving storage space is provided. The vector tile data generally comprises downloading, resolving, rendering and other stages in the map rendering process, and the requirements on the tile data format are small in size, fast in resolving and capable of generating different effects in cooperation with different styles. When the scheme of the 'Mapbox MVT' data format is adopted, the implementation steps of the vector map are as follows:
calculating the number of the vector tile according to the display requirement, and sending a downloading request;
downloading vector tile data for decoding to obtain a vector tile object;
resolving elements (features), geometric objects (Geometry), element attributes (tags) and the like in the vector tiles;
determining whether to perform proper map projection and display coordinate system transformation according to the map display coordinate system;
selecting a style for rendering according to the element attribute;
and displaying the vector map.
The map display in the network environment can be well solved by adopting the existing Mapbox MVT vector tile scheme, the analysis attribute of the space geographic data is lacked, and in the practical application, the defects are mainly shown in the following steps:
the vector tiles adopt a local small integer coordinate system based on tiles, so that the precision loss is large, and the vector tiles are difficult to fuse with tiles of various specifications;
the vector tile does not include a coordinate range and projection information, and spatial data of the vector tile cannot be independently used;
vector tile decoding and geometric object extraction have frequent creation and deletion of small memories and the like, and the use performance is low.
Disclosure of Invention
In order to solve the problem of lack of spatial geographic data analysis attribute when map display is performed in a network environment, the application provides a vector drawing method and device based on vector tile data and electronic equipment.
The embodiment of the disclosure provides a vector drawing method based on vector tile data, which comprises the following steps:
calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a downloading request link, and obtaining vector tile data;
creating vector tile objects using vector tile data based on the defined vector tile data format;
comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data, and displaying the vector map.
Further, the calculating the vector tile number according to the display scale and the display range of the map, constructing a resource link, and sending a download request includes:
a hierarchy of query requests, wherein the hierarchy of scale greater than a threshold is used as the hierarchy of requests;
calculating the size of the vector tile cell grid according to the requested hierarchy;
calculating row and column numbers of a lower left corner and an upper right corner of a hierarchy in a display range;
and obtaining a hierarchical vector tile grid within a display range, constructing a resource link of a vector tile request according to the vector tile grid, searching a request link of network service resources of the vector tile from the resource link, and sending the request resource to a server to obtain vector tile data.
Further, the creating a vector tile object using vector tile data based on the defined vector tile data format includes:
the vector tile data is indicated and stored by a memory block;
creating a vector tile object class, wherein in creating the vector tile object class, a memory block is appended to the class instance;
based on the defined vector tile data format, the method of calling the vector tile object class automatically constructs the vector tile object.
Further, the comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile object or after transforming the display projection, includes: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
Further, in the rendering of the drawing by using the geometric data, a style is selected according to the element attribute to perform drawing rendering.
Further, in the rendering of drawing according to the element attribute selection style, when the selected style information is absent, if the user has the requirement of customizing the style, the drawing is performed by acquiring the attribute information of the feature.
In another aspect, the present application also provides a vector drawing device based on vector tile data, where the device includes:
the acquisition unit is used for calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a download request link and acquiring vector tile data;
a creating unit for creating a vector tile object using vector tile data based on the defined vector tile data format;
and the drawing unit is used for comparing the vector tile data with the data in the display projection, selecting the geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data and displaying the vector map.
Further, the comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile object or after transforming the display projection, includes: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
The application has the following beneficial effects: the application provides a vector drawing technology based on vector tile data, namely, the vector drawing technology balances the size of the tile data volume and the decoding mode by constructing complete vector tile map data (the complete vector tile can be provided with a coordinate range, projection information, a display style and the like, and the single vector tile is a fast memory without secondary decoding after loading), so that the use performance of the vector tile in some special application scenes such as digital earth, digital city and the like is improved; in the application, a vector tile file structure with a spatial range, projection information, element attributes and rendering styles is provided; the vector tiles are rapidly loaded through the index occupying information, and file decoding links are removed.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a flow diagram of a vector mapping method based on vector tile data according to the present application;
FIG. 2 is a schematic diagram of a vector drawing device based on vector tile data according to the present application;
FIG. 3 is a flow chart of the vector tile loader process of the present application
FIG. 4 is a diagram of the definition of a flag for the vector tile format of the present application;
FIG. 5 is a flow chart of vector tile constructor processing of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to specific embodiments of the present application and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The following describes in detail the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.
As shown in fig. 1, the present application provides a vector drawing method based on vector tile data, which includes:
step S1: calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a downloading request link, and obtaining vector tile data;
step S2: creating vector tile objects using vector tile data based on the defined vector tile data format;
step S3: comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data, and displaying the vector map.
According to the display proportion and the display range of the map, calculating the vector tile number, constructing a resource link, and sending a downloading request, wherein the method comprises the following steps:
a hierarchy of query requests, wherein the hierarchy of scale greater than a threshold is used as the hierarchy of requests;
calculating the size of the vector tile cell grid according to the requested hierarchy;
calculating row and column numbers of a lower left corner and an upper right corner of a hierarchy in a display range;
and obtaining a hierarchical vector tile grid within a display range, constructing a resource link of a vector tile request according to the vector tile grid, searching a request link of network service resources of the vector tile from the resource link, and sending the request resource to a server to obtain vector tile data.
Creating vector tile objects using vector tile data based on a defined vector tile data format, comprising:
the vector tile data is indicated and stored by a memory block;
creating a vector tile object class, wherein in creating the vector tile object class, a memory block is appended to the class instance;
based on the defined vector tile data format, the method of calling the vector tile object class automatically constructs the vector tile object.
In some embodiments of the present application, comparing vector tile data to data in a display projection, selecting geometric data of a drawing from vector tile objects or after transforming the display projection, includes: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
In some embodiments of the application, in rendering the drawing with geometric data, a style is selected for rendering the drawing according to the element attribute.
In some embodiments of the present application, when the style information selected is missing in the rendering of drawing according to the element attribute selection style, if the user has a requirement of customizing the style, the drawing is performed by acquiring attribute information of the feature.
On the other hand, as shown in fig. 2, the present application also provides a vector drawing device based on vector tile data, which includes:
the acquisition unit is used for calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a download request link and acquiring vector tile data;
a creating unit for creating a vector tile object using vector tile data based on the defined vector tile data format;
and the drawing unit is used for comparing the vector tile data with the data in the display projection, selecting the geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data and displaying the vector map.
In some embodiments of the present application, comparing vector tile data to data in a display projection, selecting geometric data of a drawing from vector tile objects or after transforming the display projection, includes: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
The above at least one technical scheme adopted by the embodiment of the application can achieve the following beneficial effects: the application provides a vector drawing technology based on vector tile data, namely, the vector drawing technology balances the size of the tile data volume and the decoding mode by constructing complete vector tile map data (the complete vector tile can be provided with a coordinate range, projection information, a display style and the like, and the single vector tile is a fast memory without secondary decoding after loading), so that the use performance of the vector tile in some special application scenes such as digital earth, digital city and the like is improved; in the application, a vector tile file structure with a spatial range, projection information, element attributes and rendering styles is provided; the vector tiles are rapidly loaded through the index occupying information, and file decoding links are removed.
As shown in fig. 3 and 4, the fast loading technology of the vector tile provided by the application is specified by a vector tile file format, and specifically comprises a vector tile constructor, a vector tile format specification and a vector tile loader.
FIG. 3 is a vector tile construction flow for outputting vector map slices as vector tiles conforming to a vector tile data format by a vector tile constructor and storing for use, the flow comprising: acquiring a vector map; preprocessing a vector map (including projective transformation, thinning processing and style setting); constructing vector tiles (comprising clipping processing and format processing) on the vector map after preprocessing; obtaining a vector tile; and repeating the above process to finally obtain the vector tile atlas. FIG. 4 is a vector tile application flow, a process for reading vector tiles and feeding them to a map renderer to form a vector map by a vector tile loader, comprising: obtaining individual vector tiles from the vector tile atlas; vector tile loading (including transport download, object build); and carrying out map processing (including projection transformation, style setting and drawing rendering) on the loaded vector tiles to obtain a vector map.
This proposal focuses on vector tile format definition and fast loading techniques.
The vector tile data format definition in the present application includes:
the main aim of the vector tile data format in the application is to uniformly package layer information, element information, geometric information, labeling information, style information and other information required in the map drawing in a memory, and the vector tile can be quickly loaded and used by customizing a special data structure body and a reserved index table in the memory block, and meanwhile, small memory loss during vector tile decoding or format conversion is avoided. The main flag definition of the vector tile data is shown in fig. 5.
The following details the data segments in the format:
1. vector tile information: OHEADER, comprising two fixed-length data segments of OHInfo and ODInfo
File information: OHInfo, including version information, data length, etc. information
Data information: ODInfo including information such as coordinate range, number of layers, etc
2. Vector layer information
Layer index: layering, defined as a layer index occupying information, is written into the first byte offset of each layer in the vector tile constructor, and is an indefinite length data segment;
layer 1-n: OLayer
Layer information area: including information such as layer name, number of elements, etc
Element index area (features): the first byte offset, defined as element index occupancy information, written into each element in the vector tile constructor is an indefinite length data segment;
element 1-n: OFeature
Element information: including information such as element ID, type, etc
Geometric index: defining as geometric index placeholder information, a first byte offset of geometric data to be written in the vector tile constructor;
style index style: defining as style index occupancy information, a first byte offset of style data written in a vector tile constructor;
labeling an index label: defining the first byte offset of the annotation data written into the vector tile constructor as annotation index occupancy information;
labeling the style labelStyle: defining as marking pattern index occupying information, and writing a first byte offset of marking pattern data in a vector tile constructor;
style data: defining a symbol pattern and the like to be displayed on the layer;
other data areas: other data that the layer needs to carry, such as layer attributes, are defined.
Vector tile load mapping techniques include:
by adopting the vector tile data format, the implementation steps of the quick loading of the vector tile data are as follows:
the first step: according to the display proportion and the display range of the map, calculating the vector tile number to be displayed, constructing a resource link requested by a local (such as a file path) or service (such as a network address), and sending a downloading request; the detailed description is as follows:
vector tile is a pyramid grid organization mode for dividing map according to quadtree rule, and is characterized by that it uses the square of top layer as basis to make bipartite treatment, when the display Scale of top layer of map (Scale) 0 ) Range (xmin) 0 ，ymin 0 ，xmax 0 ，ymax 0 ) After determining, each tile in the tile pyramid has a unique number, generally represented by a level (zoom), a line number (y), and a column number (x), the level representing different map scales, the line number and the column number being the north-south and east-west sequence numbers of the tile grid after the level is fixed. The tile Scale (which is expressed by Scale denominator in calculation) is usually calculated based on the defined top layer range of the pixels of a certain screen area, and can be marked with Scale 0 Corresponding level Z 0 One-time amplification to obtain Scale 1 ，Scale 2 ，Scale 3 ，…，Scale zoom Corresponding level Z 1 ，Z 2 ，Z 3 ，…，Z zoom While the topmost tile has a dimension D 0 (calculated from the topmost Range D) 0 ＝xmax 0 -xmin 0 ) Represented in turn as D 1 ，D 2 ，D 3 ，…，D zoom Etc. When the map scale (scale) and the display range (x) min ，y min ，x max ，y max ) And (2) after that:
firstly, obtaining the nearest hierarchy which is larger than a given scale as a hierarchy (zoom) required by a request by using a query;
second, calculating the dimension D of the tile cell grid according to the hierarchy zoom ＝D 0 /2 zoom ；
Then calculating the rank number of the left lower corner and the right upper corner of the display range
xzoom’ Left side ＝floor((x min -x min0 )/D zoom )
yzoom’ Lower part(s) ＝ceil((y min -y min0 )/D zoom )
xzoom’ Right side ＝floor((x max -x min0 )/D zoom )
yzoom’ Upper part ＝ceil((y max -y min0 )/Dz oom )
Wherein floor function represents a downward rounding and ceil function represents an upward rounding.
Finally, a grid of tiles (x) zoom' left ，y Under zoom' ，x zoom' right ，y On zoom ) The resource link of the tile request can be constructed through the tile grid, and the tile grid (2, 3, 5) of the layer 3 is obtained through calculation in the example of the figure, so that the network service resources of the vector tiles are respectively in the form of http:// server: port/3/2/5, http:// xxxxxx/3/2/5.
And a second step of: obtaining vector tile data through a downloading request in the first step, wherein the data is downloaded into a memory block, an instance of a tile object (OData-like) can be directly created by the memory block of the vector tile data, the construction operation of the tile object is carried out through a construction function (method building) of the tile object, initialization and the like of an index area can be completed in the object, the process does not need to additionally create or destroy a memory, and the vector tile object and a layer object (layers), an element entity (Feature), a geometric object (Geometry), a labeling attribute (label), a display style (Style, labelStyle) and the like are obtained after the completion;
to achieve the goal of this step, the class diagram structure of the vector tile loader is designed based on the vector tile specification to which section "2, vector tile data format definition" belongs.
The specific operation steps comprise:
firstly, receiving a vector tile data block obtained from the first step, and indicating and storing by using a memory block unsigned char;
secondly, creating a tile object OData, wherein data=new OData (bufferData), and a memory block is added to a data instance;
and then, calling a build method of the tile object data to automatically construct, and filling a corresponding object index occupation area according to the data specification of the vector tile to finish the connection of an information area, an index area, a data area and the like in the tile object, so that the attribute of the tile object points to a correct memory address. The core idea of the automatic construction is to construct a vector tile object with a hierarchical structure and random access by utilizing a continuous memory, and the secondary indexes of layers, elements, geometry, patterns and the like are realized by filling a reserved index area, so that the aim of random access is fulfilled.
And a third step of: in the tile object data obtained in the second step, the geometric object of the element can be obtained, and whether to perform proper map projection and display coordinate system transformation is determined according to the map display coordinate system; the specific implementation flow is as follows:
in general, when displaying a map, projection information of the view needs to be set as a geographic coordinate system or a projection coordinate system according to application requirements, when rendering and drawing are performed by using tile objects, firstly, viewing display projection of the map, if original tile projection is the same as display projection, then, directly using geographic geometric objects in vector tiles as geometric data required by drawing, if the original tile data is different from the display projection, then, using the geographic geometric data subjected to projection transformation as geometric data of drawing, and then rendering and drawing are performed by using the drawing data.
Fourth step: after the drawing data are processed in the third step, a style is selected according to the element attribute to carry out drawing rendering; in the tile object data of the scheme, default style information is provided, and geometric data of drawing and the default style information are acquired in a following mode.
If the user has the requirement of customizing the style, the style of the user can be matched by using different codes through acquiring other attribute information of features, such as coding attributes, and then drawing is performed.
Fifth step: and after all the requested vector tile data are sequentially drawn, displaying a vector map.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The application therefore also proposes a computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, implements a method according to any of the embodiments of the application.
Furthermore, the application also provides an electronic device, which comprises a memory, a processor and a computer program stored on the memory and capable of being run by the processor, wherein the processor executes the computer program to realize the method according to any embodiment of the application.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In one typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of computer-readable media.
Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.
Claims (10)
1. A vector mapping method based on vector tile data, comprising:
calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a downloading request link, and obtaining vector tile data;
creating vector tile objects using vector tile data based on the defined vector tile data format;
comparing the vector tile data with the data in the display projection, selecting geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data, and displaying the vector map.
2. The vector drawing method based on vector tile data according to claim 1, wherein the calculating the vector tile number, constructing a resource link, and transmitting a download request according to the display scale and the display range of the map comprises:
a hierarchy of query requests, wherein the hierarchy of scale greater than a threshold is used as the hierarchy of requests;
calculating the size of the vector tile cell grid according to the requested hierarchy;
calculating row and column numbers of a lower left corner and an upper right corner of a hierarchy in a display range;
and obtaining a hierarchical vector tile grid within a display range, constructing a resource link of a vector tile request according to the vector tile grid, searching a request link of network service resources of the vector tile from the resource link, and sending the request resource to a server to obtain vector tile data.
3. The vector tile data-based vector drawing method according to claim 1, wherein the creating a vector tile object using vector tile data based on a defined vector tile data format comprises:
the vector tile data is indicated and stored by a memory block;
creating a vector tile object class, wherein in creating the vector tile object class, a memory block is appended to the class instance;
based on the defined vector tile data format, the method of calling the vector tile object class automatically constructs the vector tile object.
4. The vector graphics method based on vector tile data according to claim 1, wherein said comparing vector tile data with data in a display projection, selecting graphics geometry data from vector tile objects or after transforming the display projection, comprises: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
5. The vector tile data-based vector drawing method according to claim 1, wherein in the rendering of the drawing using geometric data, a style is selected according to element attributes for rendering of the drawing.
6. The vector tile data-based vector drawing method according to claim 5, wherein in the drawing and rendering according to the element attribute selection style, when the selected style information is absent, if the user has a need of a custom style, the drawing is performed by acquiring attribute information of the feature.
7. A vector drawing device based on vector tile data, comprising:
the acquisition unit is used for calculating the number of the vector tile according to the display proportion and the display range of the map, constructing a resource link, sending a download request link and acquiring vector tile data;
a creating unit for creating a vector tile object using vector tile data based on the defined vector tile data format;
and the drawing unit is used for comparing the vector tile data with the data in the display projection, selecting the geometric data of the drawing from the vector tile objects or after the display projection is transformed, rendering the drawing by adopting the geometric data and displaying the vector map.
8. The vector tile data-based vector graphics apparatus of claim 7, wherein comparing vector tile data to data in a display projection, selecting geometric data for a graphic from vector tile objects or after transforming the display projection, comprises: and viewing the display projection of the map, if the vector tile data are the same as the display projection data, taking the geographic geometric objects in the vector tile objects as the geometric data of the drawing, and if the vector tile data are different from the display projection data, performing projection transformation to obtain the geographic geometric data as the geometric data of the drawing.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method according to any of claims 1-6.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any of claims 1-6 when executing the computer program.
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| CN117392331A (en) * | 2023-12-12 | 2024-01-12 | 天津市城市规划设计研究总院有限公司 | Visualization method of CAD file in three-dimensional scene based on vector tile serialization |
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| CN117392331A (en) * | 2023-12-12 | 2024-01-12 | 天津市城市规划设计研究总院有限公司 | Visualization method of CAD file in three-dimensional scene based on vector tile serialization |
| CN117392331B (en) * | 2023-12-12 | 2024-03-12 | 天津市城市规划设计研究总院有限公司 | Visualization method of CAD file in three-dimensional scene based on vector tile serialization |
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