CN103927374B - A Method of Creating Web GIS Map Layer Based on SharpMap - Google Patents

Abstract

The present invention relates to a kind of system that local Mobile GI Service is provided based on GPS locating information, comprise wireless communication networks, GPS locating device and mobile terminal, and the Internet and server, by the analysis to a kind of Web GIS product-Sharpmap engine map of increasing income, exploitation SharpMap identity function, be applied in vehicle monitoring system, simultaneously for problems such as existing map loading velocity are slow, effective result scheme is proposed, and utilize the scheme of third party's engine map, the engine map that third party is provided and the collaborative work of this vehicle monitoring system, jointly complete vehicle location, describe the functions such as track.

Description

A Method of Creating Web GIS Map Layer Based on SharpMap

technical field

The invention relates to a geographic information system, in particular to a SharpMap-based Web GIS map.

Background technique

The vehicle monitoring system combines GPS technology, GIS technology and wireless communication technology, these three cutting-edge technologies in the world today, see Figure 1, and can remotely track and monitor vehicles anytime and anywhere. Among them, GPS technology, GIS technology and wireless communication technology are the core technologies of the vehicle monitoring system, and each technology plays an irreplaceable role in the vehicle monitoring system. As the positioning part of the vehicle monitoring system, GPS (GIobal Positioning System) technology is mainly responsible for the collection of information such as the position of the moving vehicle. GPS positioning technology is a high-precision, all-weather and global system established with the development of modern science and technology. It uses 24 artificial satellites located more than 20,000 kilometers above the earth to continuously transmit satellite positioning signals to the earth. Any GPS receiver on the earth, as long as it receives more than or equal to 4 positioning satellites The transmitted positioning signal can be used to calculate the motion state of the measured carrier, such as longitude, latitude, altitude, time, speed, etc. As the information release part of the vehicle monitoring system, the Geographic Information System (GIS for short) integrates computer graphics and databases to collect, process, transmit, store, manage, query, retrieve, analyze, express and apply geographic data. The computer system mainly includes computer hardware, software, geographic data and users, etc. It presents geographical location and related attribute information to users in a true and accurate manner with pictures and texts, and uses its unique spatial analysis ability and visual expression ability , to meet the needs of users for geographic information. Applying the electronic map under the condition of GIS to the vehicle monitoring system can provide a visual carrier for vehicle monitoring, and each Internet user can easily query the relevant geographic information and vehicle information through the electronic map. The wireless communication technology builds a data communication bridge between GPS and GIS, making remote monitoring possible. Through accurate positioning technology, communication technology and electronic map under GIS, the vehicle monitoring system can realize the positioning, tracking and monitoring of vehicles, and effectively manage the vehicles, thus making the vehicle management on a scientific and regular basis the way.

With the development and maturity of Web GIS, its application in the field of intelligent vehicle monitoring and navigation is becoming more and more extensive. In the vehicle monitoring system, the positioning data of each mobile vehicle is transmitted to the monitoring center through the communication network, and the monitoring center accurately and intuitively displays the position and driving track of each controlled vehicle through the electronic map under Web GIS. Visit the monitoring center website to inquire about the information they want to know, and implement corresponding control over the vehicle. Wqu GIS, as the main information display medium of the vehicle monitoring system, combines geographical features to display vehicle information intuitively and accurately, which is more in line with people's habits and is an indispensable part of the vehicle monitoring system. In addition, after GIS entered the Internet, changes have taken place in its implementation principles, data organization and management, system application mode, software development, user interface, etc. GIS data has also changed the traditional release mode and spread through the Internet. It will inevitably be affected by the speed of network transmission. The solutions to these problems determine the success of the system to a certain extent. At the same time, the development speed and cost of the Web GIS system are also issues that developers are concerned about. It can be seen that in the face of fierce competition, it is very important to choose a Web C platform with comprehensive functions, high speed, high reliability and low development cost to build a vehicle monitoring system.

Contents of the invention

A kind of Web GIS map loading method based on SharpMap of the present invention aims at the slow loading speed of GIS map in the prior art, the problem of high operation cost, provides a kind of Web GIS map layer creation method based on open source code SharpMap, its Features: 1) Create map; 2) Create layer: set the data source of the layer: convert other map formats into Shapefile format maps, geographic information is organized in the form of tables, and the map layer can be based on the map table The form is stored in the spatial 3D database. The spatial 3D database stores the 3D coordinate system. Map layers can be stored and displayed in atlases. They can be stored as world atlases, provincial atlases, and city atlases, which are stored in spatial databases 3) Data import: The data import mechanism in SharpMap is implemented by using Provider mode, each layer contains a different aspect of the map, and each layer corresponds to a series of database tables , introduce the map data contained in the table to the corresponding map layer through the data import mechanism, and associate the data information that the user cares about with the map object represented by the layer; 4) Coordinate transformation: the geographic space position coordinates of the map entity and The grid position coordinates in the Shapefile format file are converted, the grid resolution is calculated, and the conversion between the grid position coordinates and the two-dimensional data unit address is completed. Under the conditions of the set grid horizontal and vertical grid unit data, Complete the two-way conversion between the array subscript corresponding to the grid and the two-dimensional array unit address, thereby completing the coordinate conversion; 5) Symbol and text labeling process: the geometric data and attribute data of map symbols and text elements are correspondingly stored in the chart, and At the same time, it is stored in a folder of the spatial database. This folder is different from the above-mentioned folder for storing map data. It provides the access interface of the symbol atlas. After the spatial layer information changes, it is determined that the map symbols and text information need to be updated. Trigger the display module to update the corresponding map symbols according to the map objects that need to be updated, and update the updated symbols and text standard processes to the corresponding map layers; 6) Realization of the basic functions of the SharpMap map: change the Center property of the Map class and Zoom Attribute, which can complete the basic functions of SharpMap map, such as map color setting, outline setting, initial scale, scale setting, zoom setting, compass setting, Center attribute indicates the center point of the map display range, and Zoom attribute refers to the field of view, indicating the current display 7) The synthesis and loading process of map layers, map symbols and text, the loading process of the map can use dynamic AJAX technology to load and display the map in blocks, and complete the creation, drawing and display of the map.

The Sharpmap-based WebGIS map loading proposed by the invention effectively solves the problems of high map cost and slow loading speed.

Description of drawings

The overall structure of the vehicle monitoring system in Fig. 1;

Figure 2 The running process of ASP.NET2.0;

Figure 3 The generation and display process of the map in SharpMap;

Detailed ways

First, the source code structure of Sharpmap is deeply analyzed. The source code of the SharpMap map engine is open and can be downloaded for free from the Internet. The current stable running version is O.9. From the downloaded source code of SharpMap, we can see that the core source code of SharpMap mainly includes two folders: SharpMap and SharpMap.UI. Among them, the SharpMap project is the main body, which includes 14 namespaces, including MAP, layer, data conversion, coordinates, data, style, geometry, rendering, etc., which contain functions that can realize different functions of the map. The call can extend the function of SharpMap and add many required functions. SharpMap.UI is another folder related to user interface, which contains namespaces such as Forms and Ajax, and it provides the realization of functions related to user interface. These two folders containing the map source code are packaged into d11 files through compilation, stored under the development website of ASE.NET2.0, and are automatically called during the implementation of SharpMap. This article analyzes in detail the functions and meanings of the functions under each namespace in these two folders. Only after understanding the functions and meanings of these functions can the functions of Sharpmap be expanded and then applied to the vehicle monitoring system.

Analysis of the operation mechanism of SharpMap, SharpMap is a Map rendering library based on .Net2.0, which adopts ASP.NET, and the implementation of Sharpmap combines the operation process of ASP.NET2.0 and the process of map generation and display, and their synergy The work has completed the generation and display of the Sharpmap map. ASENET is an ISAPI extension under the Web server (usually an IIS server), and it usually exists on the Web server. When the IIS web server receives a request from the browser, it will check the extension of the requested file, and hand the request to the appropriate ASENET (ISAPI extension) according to the file extension to process, and obtain it from the database or other resources. Necessary data, and then ASENET returns the processing result to the IIS Web server, and then returns to the browser side, and its operation process is shown in Figure 2.

The generation and display process of the map in Sharpmap, the generation and display process of the map in Sharpmap is divided into creating a map, creating a layer and setting the data source of the layer, layer style setting, adding a layer to the map, map background, scale, center Several steps such as point setting and drawing and generating map, create map, as shown in Figure 3: its process comprises: a kind of Web GIS map layer creation method based on SharpMap, it is characterized in that: 1) create map; 2) create Layer: set the data source of the layer: convert other map formats into Shapefile format maps. Geographic information is organized in the form of tables. The map layers can be stored in the spatial 3D database in the form of map tables. Spatial 3D The database stores the three-dimensional coordinate system, and the map layers can be stored and displayed in atlases, which can be stored as world atlases, provincial atlases, and urban atlases, which are stored in different folders of the spatial database; 3) Data introduction : The data import mechanism in SharpMap is implemented by the Provider mode. Each layer contains a different aspect of the map, and each layer corresponds to a series of database tables. The map contained in the table is imported through the data import mechanism. The data is imported into the corresponding map layer, and the data information that the user cares about is associated with the map object represented by the layer; 4) Coordinate conversion: the geographic spatial position coordinates of the map entity are converted to the grid position coordinates in the Shapefile format file , calculate the grid resolution, complete the conversion between the grid position coordinates and the two-dimensional data unit address, and complete the array subscript and the two-dimensional Two-way conversion of the unit address of the dimensional array, thereby completing the coordinate conversion; 5) symbol and text labeling process: the geometric data and attribute data of map symbols and text elements are correspondingly stored in the chart, and stored in a folder of the spatial database at the same time, This folder is different from the above-mentioned folder for storing map data. It provides the access interface of the symbol atlas. After the spatial layer information changes, it is determined that the map symbol and text information need to be updated, and the display module is triggered to update according to the map object that needs to be updated. Corresponding map symbols, update the updated symbol and text standard process to the corresponding map layer; 6) Realization of the basic functions of the SharpMap map: change the Center property and Zoom property of the Map class to complete the basic functions of the SharpMap map, such as map Color setting, outline setting, initial scale, scale setting, scaling setting, compass setting, Center attribute indicates the center point of the map display range, and Zoom attribute refers to the field of view, indicating the width of the currently displayed map range; 7) map layer, The synthesis and loading process of map symbols and characters, the map loading process can use dynamic AJAX technology to load and display the map in blocks, and complete the creation, drawing and display of the map.

AJAX technology is applied in Sharpmap. AJAX technology is a fashionable and cutting-edge technology known to everyone in the world today. It has changed the traditional interaction mode between browsers and servers, and achieved on-demand requesting data and partially refreshing pages. , Sending requests asynchronously is a powerful way to build a website. The birth of Web2.0 has made Ajax well applied and brought a whole new situation to the construction of websites. At present, Canail, Amazon, and A9.tom search all use Ajax technology, which combines the advantages of desktop applications. Dynamics and rapidity are reflected in web applications, enabling efficient web development. It is very suitable to apply this technology in the GIS field with large amount of data and slow map loading speed. Like Google Earth and Google Maps, they have all made a splash in the GIS field because of the use of Ajax technology. Ajax technology is also introduced into Sharp№ap, which makes SharpMap powerful.

Sharpmap can realize the Chinese display of the map; the database for storing data can be a two-dimensional database; it can realize the function of sub-atlas real map data.

The Sharpmap map can be used to display vehicle positioning information and track vehicles in real time; it can perform vehicle trajectory tracking, dynamic path planning, and vehicle navigation.

The database in Sharpmap can be displayed on the same terminal as the map, or on a remote terminal; tourist information such as standard restaurants and hotels can be displayed on the map.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it still can The technical solutions described in the foregoing embodiments are modified, or some of the technical features are equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (8)

1., based on a Web GIS map layer creation method of SharpMap, it is characterized in that:

1) map is created;

2) create layer: the data source that layer is set: the map other format map being converted to Shapefile form, geography information is organized usually in the form of a table, this map layer can the form of base area chart be stored in space three-dimensional database, space three-dimensional database purchase three-dimensional coordinate system, map layer can divide atlas to carry out storing and showing, atlas of the world, provincial atlas, urban atlas can be stored as, below the different files being stored in spatial database respectively

3) introducing of data: it is take Provider pattern to realize that the data in SharpMap introduce mechanism, each layer contains a different aspect of map, and each layer correspond to a series of database table, introducing mechanism by data is incorporated on corresponding map layer by the map datum comprised in table, is associated by the data message that user pays close attention to the map object that layer represents;

4) coordinate conversion: the grid positions coordinate in the geospatial location coordinate of map entities and Shapefile formatted file is changed, computation grid resolution, complete the conversion of grid positions coordinate and 2-D data element address, under the condition of the horizontal and vertical grid cell data of the grid set, complete the bi-directional conversion of array index corresponding to grid and two-dimensional array element address, thus complete coordinate conversion;

5) symbol and label character process: the geometric data of map symbol and word key element, attribute data corresponding stored are in chart, and under being stored in a file of spatial database simultaneously, this file is different from the file of above-mentioned store map data, the access interface of this symap collection is provided, after space map data mining platform changes, determine to need to upgrade map symbol and Word message, the map object that triggering display module upgrades as required goes to upgrade corresponding map symbol, is updated in corresponding map layer by the symbol after renewal and word;

6) SharpMap map basic function realizes: the Center attribute and the Zoom attribute that change Map class, SharpMap map basic function can be completed, described map basic function comprises the color setting of map, profile setting, initial proportion, engineer's scale is arranged, scaling is arranged, compass is arranged, the central point of Center attribute representation map denotation scope, Zoom attribute refers to the visual field, represents the wide of current display body of a map or chart;

7) synthesis of map layer, map symbol and word and loading procedure, the loading procedure of described map can adopt dynamic AJAX technology piecemeal load and show map, completes the establishment of map, drafting and display.

2. the Web GIS map layer creation method based on SharpMap according to claim 1, can realize the Chinese display of map.

3. the Web GIS map layer creation method based on SharpMap according to claim 1, described database can be 2-D data storehouse.

4. the Web GIS map layer creation method based on SharpMap according to claim 1, can realize a point atlas display map data functional realiey.

5. the Web GIS map layer creation method based on SharpMap according to claim 1, can be used to the locating information, the real-time follow-up vehicle that show vehicle.

6. the Web GIS map layer creation method based on SharpMap according to claim 1, can carry out Vehicle tracing, active path planning, automobile navigation.

7. the Web GIS map layer creation method based on SharpMap according to claim 3, described database with Map Integration in same terminal, also can be arranged on remote terminal.

8. the Web GIS map layer creation method based on SharpMap according to claim 1, can mark food and drink, hotel's travel information on map.