Element service display method and system based on Cesium

Abstract

The invention belongs to the technical field of geographic information, and particularly relates to a Cesium-based element service display method and system.The method comprises the steps that an uploaded vector file containing geographic information is received and analyzed, and geometric data obtained through analysis are stored in a database; performing layer class loading at the front end, wherein a layer loading demand is initiated to the rear end according to a request of a user; the rear end queries corresponding geometric data from a database according to the received request, calculates a geometric query range by using a geometric query function, and converts a query result into data in an MVT format through an STAsMVT function; compressing the converted MVT format data, and then sending the compressed data to a front end; and after the front end receives the MVT data, dynamically presenting the MVT data according to the rendering rule. According to the method, dynamic loading and rendering of the vector data are realized in a front-end and rear-end separation mode, the data processing efficiency is improved, the autonomous controllability and safety of the system are enhanced, and the performance of geographic information service and the user experience are improved.

Description

Technical Field

[0001] The present invention belongs to the field of geographic information technology, and specifically relates to a Cesium-based feature service display method and system. Background Art

[0002] With the rapid development of geographic information system (GIS) technology, the acquisition, processing and visualization of geographic data have become an indispensable part of modern urban management, natural resource management, environmental monitoring and other fields. Traditional GIS platforms have strong advantages in data editing and analysis, but in Web applications, especially in three-dimensional visualization and real-time interactive capabilities, there are obvious limitations. For example, traditional WebGIS applications often rely on the front-end to load a large number of static feature services at one time, which not only consumes a lot of computer memory resources, but also increases the burden on the GPU, resulting in poor user experience problems such as slow page loading and operation jams.

[0003] In recent years, Cesium, as a high-performance WebGIS visualization engine, has attracted widespread attention for its support for multiple geospatial data formats, dynamic data loading, real-time rendering, and highly interactive user interfaces. Combined with spatial database technologies such as PostGIS, the above problems can be effectively solved to improve the generation efficiency and user experience of feature services. However, most of the existing Cesium-based feature service solutions rely on third-party GIS services (such as ArcGIS Server, SuperMap Server, etc.), which not only increases the cost of use, but also reduces the autonomy and security of the system. In addition, although static data slices can reduce the burden of front-end processing to a certain extent, their generation and management process is complicated, and data updates are not flexible enough. Summary of the invention

[0004] The purpose of the present invention is to provide a Cesium-based feature service display method and system, which optimizes the data processing process, improves data loading and rendering efficiency, reduces dependence on external services, and enhances the system's autonomous controllability and security through back-end services and front-end dynamic loading technology, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention proposes a Cesium-based feature service display method, comprising the following steps:

[0006] S1: Receive and parse the uploaded vector file containing geographic information, and store the parsed geometric data in the database;

[0007] S2: receiving a layer loading request, and performing layer loading on the front end according to the layer loading request;

[0008] S3: According to the layer loading request, query the target geometric data corresponding to the layer loading request from the database, and convert the target geometric data into MVT format data;

[0009] S4: Send the MVT format data to the front end;

[0010] S5: Receive the MVT format data, and dynamically present the compressed MVT data on the front end according to rendering rules.

[0011] Preferably, the receiving and parsing of the uploaded vector file containing geographic information, and storing the parsed geometric data in a database, includes:

[0012] Receive and use the geotools library to parse the uploaded vector files containing geographic information, and store the parsed geometric data in the database.

[0013] Preferably, the method further includes S6: destroying geometric data that is not within the scope of the layer loading request.

[0014] Preferably, querying the target geometry data corresponding to the layer loading request from a database according to the layer loading request, and converting the target geometry data into MVT format data includes:

[0015] According to the layer loading request, the geometry query range is calculated using the geometry query function, the target geometry data corresponding to the layer loading request is queried from the database, and the target geometry data is converted into MVT format data through the ST_AsMVT function of PostGIS.

[0016] On the other hand, the present invention proposes a Cesium-based feature service display system, comprising:

[0017] The data parsing module is used to receive and parse the uploaded vector files containing geographic information, and store the parsed geometric data in the database;

[0018] A layer loading module, used to receive a layer loading request and load the layer at the front end according to the layer loading request;

[0019] A data processing module, used for querying target geometric data corresponding to the layer loading request from a database according to the layer loading request, and converting the target geometric data into MVT format data;

[0020] A data transmission module, used for sending the MVT format data to the front end;

[0021] The rendering module is used to receive the MVT format data and dynamically present the compressed MVT data on the front end according to the rendering rules.

[0022] Preferably, the data parsing module is used to receive and use the geotools library to parse the uploaded vector file containing geographic information, and store the parsed geometric data in a database.

[0023] Preferably, a resource management module is also included for destroying geometric data that is not within the scope of the layer loading request.

[0024] Preferably, the data processing module is used to calculate the geometric query range using the geometric query function according to the layer loading request, query the target geometric data corresponding to the layer loading request from the database, and convert the target geometric data into MVT format data through the ST_AsMVT function of PostGIS.

[0025] Technical effects and advantages of the present invention: Compared with the prior art, the present invention provides a method and system for displaying element services based on Cesium, which has the following advantages:

[0026] The present invention realizes dynamic loading and rendering of vector data by separating the front-end and back-end, effectively reducing the consumption of front-end memory space and GPU resources. At the same time, through customized layer loading classes and rendering rules, a richer and more flexible geographic information visualization method is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of a method for displaying feature services based on Cesium of the present invention;

[0028] Figure 2 A block diagram of a Cesium-based feature service display system of the present invention;

[0029] Figure 3 It is a schematic diagram of the structure of the terminal device of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The present invention provides a feature service display method based on Cesium, which aims to optimize the data processing process and improve the efficiency of data loading and rendering through self-developed back-end services and front-end dynamic loading technology, while reducing dependence on external services and enhancing the autonomy, controllability and security of the system.

[0032] The professional terms mentioned in this article need to be explained:

[0033] Feature Service: Feature Service is a complete service composed of geometric data and attribute data. It includes not only geometric data, but also related attribute data (such as name, type, etc.), style definition and metadata. In the field of GIS (Geographic Information System), it usually refers to a service that provides access to geospatial data, which allows users to query, browse, analyze and edit geospatial data.

[0034] Geometric data: refers to the spatial attribute part of vector data, that is, the geometric shapes of points, lines, and surfaces.

[0035] Mvt: Mvt stands for Mapbox Vector Tile. As a vector tile specification exclusively defined by Mapbox, it is known for its lightweight data architecture and is designed specifically for carrying vector data in geographic space, such as point sets, lines, polygons and other geographic elements. This technical path not only simplifies the data slicing process, but also facilitates the instant rendering of data on the client, providing users with a smooth map interaction experience.

[0036] Cesium: Cesium is a high-performance open source JavaScript library designed for creating rich 3D earth and 2D map visualizations in web browsers. It supports multiple geospatial data formats, provides dynamic data loading, real-time rendering, and a highly interactive user interface, making it an ideal choice for building Web GIS applications.

[0037] PostGIS: PostGIS is an extension of the PostgreSQL database, which transforms PostgreSQL into a powerful spatial database system. It supports the storage, indexing, querying, and analysis of geospatial data, provides a series of spatial functions and operations, and enables users to efficiently manage and query geospatial data. It is an important part of geographic information system development.

[0038] like Figure 1 As shown, in this embodiment, a method for displaying a feature service based on Cesium includes the following steps:

[0039] S1: Receive and parse the uploaded vector file containing geographic information, and store the parsed geometric data, attribute data and coordinate system information in the PostgreSQL database;

[0040] Specifically, vector files include but are not limited to shp, geojson and other formats, and support the storage of various geometric data and their attributes such as points, lines, and surfaces. In addition, the geotools library is used to parse vector files to ensure that the data is accurately stored in the PostgreSQL database.

[0041] Furthermore, the vector file is parsed through the geotools library, and the pg library table is created. The geometric data, attribute data, and coordinate system are stored and managed in the table to facilitate subsequent data processing and query.

[0042] S2: Implement a custom MVTImageryProvider layer loading class on the front end. The layer loading class initiates a request to the back end based on the user's layer request (including layer name, zoom level, X, Y position);

[0043] By dynamically requesting MVT data, only the vector data within the current layer loading request range is loaded, which greatly reduces the memory usage and GPU resource consumption of the front end. Users can select different layer names, zoom levels and locations as needed to achieve personalized map display.

[0044] Customized rendering rules can better adapt to different types of vector data and provide a smoother user interaction experience. Combined with the backend geometry query function, users can perform complex geometry and attribute queries to meet the needs of diverse application scenarios.

[0045] S3: The backend uses the geometry query function of PostGIS to calculate the geometry query range according to the layer loading request, queries the target geometry data corresponding to the layer loading request from the database, and converts the query result into MVT format data through the ST_AsMVT function;

[0046] Furthermore, the backend logic also includes caching the generated MVT data to speed up the response speed of subsequent identical requests.

[0047] Through the geometric query function of PostGIS, the geometric query range is accurately calculated to ensure that only data within the current layer loading request range is queried, thereby improving query efficiency. The ST_AsMVT function is used to convert query results into MVT format data for efficient front-end rendering.

[0048] The generated MVT data is cached, and subsequent identical requests can be read directly from the cache, significantly improving response speed, reducing the number of database queries, and reducing server load. The backend logic is clear, easy to maintain and expand, and more functions and optimization measures can be added according to actual needs.

[0049] Through the above implementation, the present invention not only improves the query and conversion efficiency of geographic information data, but also significantly improves the system performance and user experience through the cache mechanism.

[0050] S4: Compress the converted MVT format data and send it to the front end; compress the MVT data using GZIP or other compression algorithms. Send the compressed data to the front end as an HTTP response and set an appropriate response header to inform the front end that the data has been compressed.

[0051] Through GZIP compression, the size of MVT data is significantly reduced, reducing network transmission time and bandwidth consumption. Compressed data is transmitted faster, and the front end can receive and render data faster, improving the user experience.

[0052] Compression reduces the bandwidth pressure on the server, especially in high-concurrency scenarios, which can significantly improve the stability and performance of the system. Combined with the cache mechanism, compressed data can be read directly from the cache, further accelerating the response speed.

[0053] S5: After receiving the MVT data, the front end dynamically presents the MVT data according to the customized rendering rules; the front end supports users to query the detailed attribute information of the geometric data through interactive operations (such as clicking), providing a rich user interaction experience.

[0054] The front end receives the MVT data returned by the back end, parses the MVT data, extracts the geometric data and attribute information, and dynamically presents the MVT data according to the customized rendering rules, supporting users to query the detailed attribute information of the geometric data through interactive operations (such as clicking).

[0055] The front end dynamically presents MVT data according to custom rendering rules, and supports the rendering of various geometric figures such as points, lines, and surfaces. Users can query detailed attribute information by clicking on geometric data, providing a rich user interaction experience.

[0056] By dynamically loading and rendering MVT data, the front end can efficiently process large amounts of geographic information data, reducing memory usage and GPU resource consumption. Users can intuitively view and interact with geographic information, enhancing the visualization and practicality of the map.

[0057] S6: Destroy geometric data that is not within the scope of the layer loading request to reduce front-end memory usage and GPU resource consumption. Regularly detect the elements within the current layer loading request range, and adopt a conditional destruction strategy for the elements that are not within the scope of the layer loading request to release related resources to ensure that the destroyed elements do not affect the user experience, and reload them when necessary.

[0058] Through the conditional destruction strategy, the front end can timely release the memory occupied by the elements that are not within the scope of the layer loading request, reducing memory usage. Reducing the rendering of elements that are not within the scope of the layer loading request reduces the burden on the GPU and improves rendering efficiency.

[0059] Regularly execute conditional destruction strategies to ensure that the front end remains efficient when processing large amounts of geographic information data, avoiding freezes and delays caused by insufficient resources. Users can enjoy a smooth interactive experience when browsing maps, and maintain good performance even in the case of large amounts of data.

[0060] This method uses the front-end and back-end separation method to decouple feature services. Different from the traditional front-end directly accessing static server resources for display, this method dynamically loads MVT data through the interface to achieve the rendering effect of vector data. On the other hand, by customizing the feature layer, only feature services within the visible range are rendered, thus saving memory space and GPU resources on the web side.

[0061] This method is cost-saving and self-controllable. It does not use third-party GIS services such as acgisserver and supermap server for forced binding, but uses Java language and related open source ecology for self-research and development, which can reduce the cost of use to a certain extent and improve the security of self-controllable data.

[0062] This method is different from the traditional one-time loading method. It reduces request pressure and speeds up interface request response and front-end rendering loading through front-end dynamic slicing and server-side cache processing technology, thus comprehensively improving the map usage experience.

[0063] The feature service generated by this method provides users with the function of dynamically modifying the map data style, which enhances the degree of map customization. From the perspective of granularity, the MVT service is managed by geometry, which enhances the ability to render map details and improves the map usage experience.

[0064] This method converts and stores the uploaded vector data into a postgis database through a series of automated processing flows. According to the layer zoom level, X, Y position requested by the GIS engine front end, an mvt vector geometry data file is generated. By setting the style, the corresponding feature service can be loaded in cesium, thereby achieving efficient and smooth geographic information visualization. The back end provides the ability of geometry query and attribute query, thereby realizing the query capability of feature services and meeting the needs of diverse scenarios.

[0065] This method optimizes the data processing process, improves data processing efficiency and front-end rendering performance through a self-developed feature service generation method, and provides users in different usage scenarios with a richer and more flexible way to visualize geographic information.

[0066] On the other hand, this embodiment provides a Cesium-based feature service display system, such as Figure 2 As shown, including:

[0067] The data analysis module is used to receive and parse the uploaded vector files containing geographic information, and store the parsed geometric data in the database; the data analysis module supports multiple vector file formats to ensure the diversity of data sources.

[0068] A layer loading module, used to receive a layer loading request and load the layer on the front end according to the layer loading request;

[0069] The data processing module is used to query the target geometry data corresponding to the layer loading request from the database according to the layer loading request, and convert the target geometry data into MVT format data; the data processing module is integrated with a cache mechanism for quickly responding to repeated data requests.

[0070] A data transmission module, used for sending the MVT format data to the front end;

[0071] The rendering module is used to render and display the MVT data received by the front end according to custom rules;

[0072] The resource management module is used to adopt a conditional destruction strategy to save resources for feature services that are not within the scope of the layer loading request.

[0073] Offline deployment module for making the system function normally without internet connection.

[0074] The query module is used to implement the functions of geometric query and attribute query, and supports users to perform complex geospatial query operations. Through the click interaction mechanism, users can easily query the attribute information of geometric data. At the same time, with the powerful functions of PostGis, the system supports complex geometric query operations, such as geometric equality, intersection, inclusion, coverage and other relationship queries. These functions provide strong support for further geospatial analysis and mining work (such as spatial query, statistical analysis, etc.). The front end clearly presents the query results to the user through intuitive visualization, realizing deep insight and utilization of data.

[0075] The above-mentioned data parsing module, layer loading module, data processing module, data transmission module, rendering module, resource management module, offline deployment module, and query module are also used to implement other steps of the above-mentioned Cesium-based feature service method when executed, which will not be described one by one here.

[0076] In addition, the present invention also provides a terminal device. The Cesium-based feature service method involved in this embodiment is mainly applied to the terminal device, which can be a PC, a portable computer, a mobile terminal, or other device with display and processing functions.

[0077] Specifically, the terminal device may include a processor (such as a CPU), a communication bus, a user interface, a network interface, and a memory. The communication bus is used to realize the connection and communication between these components; the user interface may include a display screen (Display), an input unit such as a keyboard (Keyboard); the network interface may optionally include a standard wired interface, a wireless interface (such as a WI-FI interface); the memory may be a high-speed RAM memory, or a stable memory (non-volatile memory), such as a disk memory, and the memory may optionally be a storage device independent of the aforementioned processor.

[0078] Among them, the memory stores a readable storage medium, the readable storage medium stores a service program, the processor can call the service program stored in the memory, and execute the Cesium-based feature service method provided by an embodiment of the present invention.

[0079] It is understood that a readable storage medium can be a tangible device that can hold and store instructions used by an instruction execution device. Computer-readable storage media can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above. More specific examples of computer-readable storage media (a non-exhaustive list) include: portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), static random access memories (SRAM), portable compact disk read-only memories (CD-ROM), digital versatile disks (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or raised structures in grooves on which instructions are stored, and any suitable combination of the above. The computer-readable storage medium used here is not to be interpreted as a transient signal itself, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0080] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0081] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0082] The terms involved in this embodiment are explained as follows:

[0083] GIS (Geographic Information Science) service: an interface that can be used to load and display 3D services on the web.

[0084] Cesium: Cesium is a high-performance open source JavaScript library designed for creating rich 3D earth and 2D map visualizations in web browsers. It supports multiple geospatial data formats, provides dynamic data loading, real-time rendering, and a highly interactive user interface, making it an ideal choice for building Web GIS applications.

[0085] PostGIS: PostGIS is an extension of the PostgreSQL database, which transforms PostgreSQL into a powerful spatial database system. It supports the storage, indexing, querying, and analysis of geospatial data, provides a series of spatial functions and operations, and enables users to efficiently manage and query geospatial data. It is an important part of geographic information system development.

[0086] Mvt: Mvt stands for Mapbox Vector Tile. As a vector tile specification exclusively defined by Mapbox, it is known for its lightweight data architecture and is designed specifically for carrying vector data in geographic space, such as point sets, lines, polygons and other geographic elements. This technical path not only simplifies the data slicing process, but also facilitates the instant rendering of data on the client, providing users with a smooth map interaction experience.

[0087] Feature service: Generate slices in real time through the database, dynamically load them through the front-end 3D engine, and display them visually. It also allows operations such as mouse click interaction and attribute query.

[0088] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Cesium-based feature service display method, applied to Cesium, characterized in that: The following steps are involved: S1: Receive and parse the uploaded vector file containing geographic information, and store the parsed geometric data in the database; S2: receiving a layer loading request, and performing layer loading on the front end according to the layer loading request; S3: According to the layer loading request, query the target geometric data corresponding to the layer loading request from the database, and convert the target geometric data into MVT format data; S4: Send the MVT format data to the front end; S5: Receive the MVT format data, and dynamically present the compressed MVT data on the front end according to rendering rules.

2. According to the Cesium-based feature service display method of claim 1, it is characterized in that: The receiving and parsing of the uploaded vector file containing geographic information, and storing the parsed geometric data in a database, includes: Receive and use the geotools library to parse the uploaded vector files containing geographic information, and store the parsed geometric data in the database.

3. According to the Cesium-based feature service display method of claim 1, it is characterized in that: Also includes: S6: Destroy the geometric data that is not within the scope of the layer loading request.

4. According to the Cesium-based feature service display method of claim 1, it is characterized in that: The step of querying target geometric data corresponding to the layer loading request from a database according to the layer loading request, and converting the target geometric data into MVT format data includes: According to the layer loading request, the geometry query range is calculated using the geometry query function, the target geometry data corresponding to the layer loading request is queried from the database, and the target geometry data is converted into MVT format data through the ST_AsMVT function of PostGIS.

5. A Cesium-based feature service display system, characterized in that: include: The data parsing module is used to receive and parse the uploaded vector files containing geographic information, and store the parsed geometric data in the database; A layer loading module, used to receive a layer loading request and load the layer at the front end according to the layer loading request; A data processing module, used for querying target geometric data corresponding to the layer loading request from a database according to the layer loading request, and converting the target geometric data into MVT format data; A data transmission module, used for sending the MVT format data to the front end; The rendering module is used to receive the MVT format data and dynamically present the compressed MVT data on the front end according to the rendering rules.

6. A Cesium-based element service display system according to claim 5, characterized in that: The data parsing module is used to receive and use the geotools library to parse the uploaded vector file containing geographic information, and store the parsed geometric data in a database.

7. The Cesium-based feature service display system according to claim 5, characterized in that: It also includes a resource management module for destroying geometric data that is not within the scope of a layer load request.

8. The Cesium-based feature service display system according to claim 6, characterized in that: The data processing module is used to calculate the geometric query range using the geometric query function according to the layer loading request, query the target geometric data corresponding to the layer loading request from the database, and convert the target geometric data into MVT format data through the ST_AsMVT function of PostGIS.

Images