Brief introduction of system construction

(A) the basic ideas and principles of design and development

The research work of agricultural land classification in Hainan Province involves a large number of basic data such as spatial geographic data and attribute data. In order to ensure the quality of agricultural land classification data and the reliability of results, improve work efficiency and save work costs, a series of related information systems were designed and developed.

1. Basic idea

The requirements of design and development are constantly improving, which not only ensures the reliability of software and hardware, but also takes into account the upgrade, expansion and inheritance of the future system; We should not only consider the diversity and compatibility of data sources, but also ensure that they are updated in time; The system has good stability, inheritance, repeatability, expansibility, operability and maintainability.

2. Design and development principles

(1) Follow the principle of giving consideration to both laws and regulations and technological innovation. We should not only follow the relevant technical regulations promulgated by the state, but also follow the development of contemporary high technology, rationally apply all kinds of advanced technological achievements and related theoretical methods, innovate in ideas and methods, and improve the technical level and advanced nature of system development.

(2) Object-oriented principle. Object-oriented methods form classes by abstracting entities with the same or similar attributes and encapsulating entities and entity operations. Using encapsulation, inheritance and polymorphism of classes to design modules.

(3) Modular design principle. Using the method of combining structure and modularization in software engineering development, the system is analyzed and divided into modules from top to bottom according to the work requirements. On the basis of investigating users' needs, the system modules are defined, the lowest building module is established, and the application-oriented "upper module" is formed through connection.

④ Consistency principle. Based on the existing technical regulations, we will strive for standardization, standardization and unification, and the phased implementation will be consistent with the overall planning. Organizational style, interface style, operation mode and data interface, as well as the setting of system variables, the call of modules and the relationship between modules should be consistent.

(5) The principle of separating application from data. By separating the system program code from the graphic database and attribute database, the portability and maintainability of the system are improved.

(6) Safety principle. Ensure the safety function of the system operation result data, and the system designs corresponding data backup.

(2) Overview of series information systems

The series information system of agricultural land grading and evaluation in Hainan Province (referred to as "series information system" for short) was designed and developed by the project team based on SuperMap platform, which adopted the integrated management of land and resources spatial database and the C/S architecture of multi-layer system, and used GIS components. The system has the characteristics of powerful function, simple use, full service integration, full network operation mode, support for remote service processing and so on, and has high expansibility and expansibility in management and maintenance. This series of information systems includes Hainan agricultural land classification system, Hainan agricultural land classification and evaluation system, soil digitization software, field survey map printing software, field survey data entry software, field survey sample data verification software, plotting line processing software, plot setting system software, plot setting and positioning system software and drawing.

Figure 3-59 Interface Diagram of Agricultural Land Classification System in Hainan Province

Figure 3-60 Interface Diagram of Agricultural Land Classification and Evaluation System in Hainan Province

Figure 3-6 1 Interface Diagram of Soil Digitization Software

Figure 3-62 Field Survey Diagram Print Software Interface Diagram

Figure 3-63 Interface Diagram of Field Data Input Software

Figure 3-64 Interface Diagram of Field Survey Data Verification Software

Figure 3-65 Interface Diagram of Border Processing Software

Figure 3-66 plot setting system software interface diagram

Figure 3-67 Software Interface Diagram of Sample Setting and Positioning System

Figure 3-68 Drawing Tool Software Interface Diagram

Figure 3-69 Interface Diagram of Land Suitability Evaluation System

Figure 3-70 Interface Diagram of Occupancy Compensation Balance Expert System

(3) the structure of serial information system

Overall structure of 1. series information system

Series information system consists of system construction platform, relational database, system operation platform and business operation series system. As shown in figure 3-7 1.

Figure 3-7 1 Series Information System Construction Platform Schematic Diagram

Based on relational database, this series of information systems integrates metadata, workflow data, business data, spatial data, archive data and file data. Based on information network, the system construction platform composed of metadata definition component, map application definition component and information exchange definition component is used for unified system maintenance, which realizes the unified construction and maintenance of a series of information systems and has high scalability.

Relying on the system operation platform composed of a series of information systems, electronic archives components, map application operation components, information exchange operation components and various business operation components, taking the data center as the hub, and using information collection, analysis and evaluation as the data source, the relevant field basic information such as land basic information, soil basic information, field survey data, topographic map information and basic geographic information. With the unified information standard, relevant policies, regulations and management system, specialization and information management as the guarantee, a series of agricultural land grading and evaluation information systems integrating GIS, GPS and RS are realized.

2. System operation mode

(1) system adopts a unified operation mode, forming a completely networked operation environment.

(2) Unified data specifications and coding standards facilitate data exchange and sharing, and support information exchange with the Provincial Department of Land and Resources and the Ministry of Land and Resources.

(3) Data formats support general exchange standards, DXF, E00, VCT and other formats.

(4) The software and its development tools support spatial database technology, SuperMap SDX+, ArcSDE, ORACLE Spatial and other spatial databases.

(5) Systems at all levels have common data exchange interface definitions, software tools and exchange methods.

(6) There are standardized technical reference documents in the system development process.

3. Data management mode

In data management, it is a centralized data management model because it adopts a unified system organization. Multi-level distributed data management mode emphasizes hierarchical, centralized and decentralized management mode. For different business departments, they can set up their own data centers to manage the spatial data of all management areas in a unified way. Subordinate departments can choose data management mode according to the actual situation, set up their own data center, manage the spatial data and attribute data of agricultural land grading and evaluation in all management areas in a unified way, and access and exchange data through the network.

4. Network logical topology

The network logical topology of the system will adopt the "remote standby cluster structure" to support the system operation mode and data storage mode, as shown in Figure 3-72.

Figure 3-72 Logical Topology Diagram of System Network

The remote backup system is composed of two remote computer rooms and corresponding server systems, and the data between remote servers is synchronized through the private network. Under normal circumstances, the database servers in the local area networks of the two places are running at the same time. When one server fails, the other server can be used to continue working. The structure has the following characteristics:

(1) Disaster tolerance in different places: When a catastrophic accident occurs in one place, the system in another place can still run, and the data will not suffer devastating losses (including redundant storage of data in different places in county-level systems).

(2) High performance: it is beneficial to improve the system performance to realize dual-machine non-redundant backup and make full use of processing power. Because a large number of spatial information access uses local storage, the operation speed is greatly accelerated.

(3) Low bandwidth: Due to the data synchronization of the server, the convergence of network traffic on the key route of wide-area connection is avoided, and the bandwidth requirement for cross-subnet access is effectively reduced.

(4) Low cost: Under the current network conditions, this structure can realize low-cost software and hardware, with simple maintenance and low operating cost. Compared with centralized "dual-computer cluster mode", "remote standby cluster structure" is a loose cluster structure, which not only helps to improve the stability and security of the system, but also greatly improves the performance of the system.

5. Develop the deployment structure

In software design, the system is designed according to three-layer model, namely, data service layer, application logic layer and user interface layer. The application logic layer mainly undertakes various application components to complete the functions of the system. Components have good reusability, and can be upgraded independently, adding new interfaces (properties and methods) without affecting the original system. In addition, reusable components can be used to build new application subsystems, which will be divided according to business functions and institutional composition. Its structure is shown in Figure 3-73.

Figure 3-73 Software Three-layer Model Diagram

This series of information systems is based on the software architecture of GIS mode. The top layer is the user interface, and the middle layer is the application service layer, which is mainly composed of various system components and application service systems to realize the functions of the system and complete the access to the database. The bottom layer is the database layer, which is mainly a large management database system such as SQL Server, and the database system runs on operating systems such as Windows.

(4) Configuration of serial information system

1. Hardware configuration

The network and hardware configuration of the series information system is shown in Figure 3-74.

Figure 3-74 Network and Hardware Configuration Diagram

2. Software Configuration Summary

See Table 3-90 for details.

Table 3-90 Software Configuration Table

sequential

(v) Evaluation of a series of information systems

This series of information system is a set of practical data visualization information system for data processing, calculation, drawing, decision analysis and other applications based on SuperMap component according to the relevant requirements of Agricultural Land Classification Regulations, Agricultural Land Classification Regulations and Agricultural Land Valuation Regulations promulgated by the Ministry of Land and Resources, combined with the actual needs of this research work.

1. General performance evaluation

(1) system efficiency. This series of information systems are developed by visualization technology and SuperMap GIS technology, and run in Windows 2000/XP environment, with good user interface, convenient operation, timely and accurate spatial information and attribute information, complete query functions and fast query speed. The system has good fault tolerance and can properly handle all kinds of capture errors; After the system completes each task, its thread will automatically close, occupying less system resources and using resources more efficiently.

② System reliability. The system runs stably. The system provides data backup and disaster recovery functions. When the user data is wrong or lost, the system can recover the user data in time.

(3) scalability. The system adopts geographic information system technology. In the development process, the system reserved the interface for establishing decision support system and expert system. Therefore, when the function module needs to be added, it can be realized without major changes to the existing system, and it has good scalability.

④ portability. The spatial database of the system can exchange data with ArcInfo, MapInfo and AutoCAD. The system can be transplanted to any computer with Windows 2000/XP operating system. At the same time, the system can be compatible with a large number of other land and resources data.

2. Evaluation of professional performance indicators

(1) data standardization and normalization. The system development mainly adopts the methods, parameters, codes and related mathematical standardization models in Agricultural Land Classification Rules, Agricultural Land Classification Rules and Agricultural Land Valuation Rules promulgated by the Ministry of Land and Resources, which ensures the standardization and standardization of data and is conducive to the sharing of land and resources data and the popularization and application of software in the whole province and even the whole country.

② Data compatibility. The system adopts component GIS software SuperMap as the development platform, which can realize the input of vector data and raster data. At the same time, the system can be common with the data formats of mainstream GIS software such as MapInfo, ArcInfo, ArcView and AutoCAD. It has the function of accepting bmp, grid, mrsid, tif and ecw image files, and realizes the transformation of raster data (such as soil map, land use status map, landform map, topographic map, etc.). ) is converted into vector data through the screen digitization function provided by the system. At the same time, the system can export related data sets (such as soil map, land use status map, town location, town boundary and county boundary) to various information system data sources such as MapInfo, ArcInfo, ArcView, AutoCAD and international vector exchange format.

(3) Spatial analysis function. The system can superimpose vectorized layers such as soil map, land use status map and landform map to obtain the unit map of agricultural land grading and evaluation, and then after a series of spatial data processing and analysis such as buffer analysis, polygon merging, layer copying and copying, the data layers needed by users can be obtained.

④ Map output. Through the layers of agricultural land grading evaluation unit, land use mode, township name and related attribute data, the system provides a variety of thematic map making guides, such as single-value thematic map, segmented thematic map, hierarchical symbol thematic map, point density thematic map, statistical thematic map, title thematic map and user-defined thematic map. In the process of map making, the map can be filled with colors, lines and other styles according to the needs of users, and related map elements can be laid out according to the needs. Through the above settings, you can output related maps such as agricultural land classification, grade and benchmark land price.

(5) Analysis of economic and social benefits. Using component GIS software as the development platform, the system development cost is low and the operation and maintenance cost is low; The system can provide practical computer management tools for management departments and government departments at all levels to quickly and conveniently grade and evaluate agricultural land, save a lot of manpower, material resources and financial resources, and reduce unnecessary duplication of work; It can provide a solid foundation and application examples for the establishment of land resource information database, digital land and digital earth in China, promote the rational management of land in China and solve a series of contradictions in the process of urbanization and industrialization.

The Ministry of Land and Resources spoke highly of the appraisal of scientific and technological achievements in this study, "among which the framing line processing software and soil digitization software are the first in China".