(Shandong Normal University, Jinan, 2500 14)
With the development of market economy, land price plays an increasingly important role in regulating social economy. Dynamic monitoring and updating of urban land price is an important means to accurately grasp the law of land price. Based on the analysis of related achievements in the field of dynamic monitoring of urban land price, an information system for dynamic monitoring and updating of urban land price based on MapX is designed and implemented. The empirical results in Jinan show that the system improves the construction efficiency of land price information database, realizes the integration of various land price calculation models and the rapid update of land price, and can conveniently query and output the results report, thus improving the scientificity, accuracy and current situation of the results.
Keywords: urban land price; Dynamic monitoring; MapX
The concept of "land price dynamic monitoring" was first put forward in 1999 [1] land resources survey, and in 2002, the Technical Specification for Urban Land Price Dynamic Monitoring System was promulgated. As a technical regulation, this paper has played a great role in the implementation of land price monitoring and land price renewal. At the same time, many scholars have optimized the key links in the establishment of monitoring system, such as the division of land price sections and the selection of land price monitoring points [2], and have done a lot of work in digital land price model [3,4] and land price spatial-temporal analysis. In this process, people gradually have a clear understanding of the significance, concept, working route and application field of dynamic monitoring of urban land price. The purpose of dynamic monitoring of land price is to monitor and warn the land market, serve the government's decision-making and adjust the market economy. At present, there is little research on the development of urban land price dynamic monitoring system in China. In view of this, it is necessary to establish a dynamic monitoring and updating information system of urban land price based on technical process. This paper aims to build such a platform, improve the operability, scientificity, accuracy and actuality of dynamic monitoring of urban land price, and better provide a basis for the work of land and resources departments and the government's macro-control decision-making.
1 demand analysis
The state has clear requirements for the establishment of dynamic monitoring system in cities. The dynamic monitoring system of urban land price is based on the specific parcels in the city, from the establishment of land price monitoring points, data collection, summary and collation to land price analysis, the application of monitoring data and the maintenance and update of the system [5]. Land price dynamic monitoring, land grading and benchmark land price evaluation are mutually beneficial and complementary [6].
The dynamic monitoring system of urban land price focuses on the dynamic monitoring of land price and the rapid update of benchmark land price. This system mainly aims at these two aspects to improve related technologies, improve work efficiency and accuracy, provide a basis for the government's macro-decision more scientifically, and improve the government's macro-control ability in the market economy.
The first-hand data of dynamic monitoring is the relevant data of monitoring points, which mainly comes from the real-time survey data and transaction sample data of the selected parcel monitoring points. How to improve work efficiency and ensure the accuracy of data is very important. In this link, two requirements are put forward for the design of the system. First, the system is required to realize the report output function of the monitoring point questionnaire and realize the rapid entry of monitoring point data, in which it is an important technical measure to let the system automatically obtain some on-site information of monitoring points; The second is to directly call the existing transaction sample data to realize the rapid storage of information. The system construction based on GIS can greatly improve the work efficiency, and has a strong support function for the attribute inspection of graphic elements and the calculation of land price results.
From the technical process of dynamic monitoring, the division of land price sections and the selection of land price monitoring points are also an important link. There is a lot of research in this field, and it is also clearly stated in the specification. According to the rules, it is easy to realize in GIS software, so it is not considered in this system for the time being. The key point of this link is to update the monitoring data in time.
The renewal of benchmark land price refers to the process of comprehensive or partial adjustment of benchmark land price with land income, market land price or land price index on the basis of land grading or homogeneous regional division [7]. There are three methods to update the benchmark land price [8]. The design of this system is based on workflow, which can automatically update the land price of monitoring points, lots and grades. Because the dynamic monitoring and updating of land price needs continuity and cohesion, the bottom-up benchmark land price updating method based on monitoring point land price updating-section land price updating-grade land price updating has the advantages of short cycle, high efficiency, cost saving and strong operability.
In view of the above analysis, the system plans to adopt component-oriented development technology, that is, embed GIS components into a general development environment. It can not only give full play to the query and spatial analysis functions of GIS, but also realize various land price calculation models and methods through programming language, thus realizing various report functions and achieving the purpose of efficient and seamless system integration. This paper decided to use MapX, a component product of MapInfo Company, for secondary development [9, 10], and chose the object-oriented VB platform as the development platform, with simple language and convenient system maintenance.
Design of Urban Land Price Dynamic Monitoring and Updating Information System Based on MapX
The main functional modules of the system are designed as shown in figure 1.
Figure 1 system function module diagram
2. 1 GIS database editing module
This module is used to realize the functions of inputting, modifying, saving, adding, deleting and backing up the basic space and attribute information of GIS database [1 1], which is the premise of the follow-up work.
The database of the system is mainly composed of three sub-databases: water level information database, section information database and monitoring point information database. Because of the small amount of data, it is stored in file format. At the same time, it supports the binding of Access database to meet the needs of attribute data calculation and analysis. The system can conveniently draw monitoring point primitives and input attribute information, and data input can be carried out in two operation modes: card type and recording type. The interactive query of attribute information and spatial information is realized, and the monitoring points are automatically numbered according to the input time, and the default information of monitoring points, such as land level, is automatically input by the computer. There are also two ways to edit information: cards and records. The system automatically records the modification time and backs up the original records, which need to be used in the calculation of land price index.
2.2 Land price information retrieval query and thematic analysis module
Spatial query and analysis, as the basic function of GIS, is an important means to query and analyze land prices. Monitoring points, sections and other information can be cross-queried by spatial information and attribute information [12], and then important rule information can be mined by SQL query. By analyzing the thematic maps of monitoring points and generating three-dimensional thematic maps such as histograms, we can visualize the distribution law of land prices, study the spatial distribution law of qualified monitoring points, and provide intuitive basis for decision-making.
2.3 Land price update module
2.3. 1 Land price evaluation and update of monitoring points
In this sub-module, two links are involved: standardized processing of monitoring point data and land price evaluation by different methods.
(1) Due to the inconsistent land use status of monitoring points, it is necessary to modify the land use period, land development degree, plot ratio, benchmark date, etc. That is, standardize the data and unify the connotation of land price to the standard land price. This is achieved by modifying the coefficient table after inputting the information.
(2) Different methods can be used to evaluate the parcel price, such as income reduction method, market comparison method and cost approximation method.
2.3.2 Calculation and update of land price.
On the basis of monitoring point land price evaluation, the land price of section can be updated. According to the types of section monitoring points, the section land price is calculated by using the average land price of sample points in the region. Firstly, the road section that needs to be updated is selected, and the monitoring points located in this road section are selected through the query function of MapX component. The field value of land price of monitoring points (obtained in the sub-module of land price calculation of monitoring points) is averaged, and the land price of this section is updated by regional average land price method.
Among them, when selecting the land price section to be updated, there are two ways: attribute query selection and direct click on the graphic element selection. In the process of monitoring point selection, the layered method is adopted. SearchWithinFeature is adopted, and the parameter is miSearchTypeCentroidWithin. The central point of the monitoring point parcel determines the ownership of the monitoring point and avoids the duplication of monitoring points in different sections.
2.3.3 Calculation and update of primary land price
Urban land grading and benchmark land price evaluation is an important work. If the factor grading method is used every time the land price is updated, it is not only inefficient, but also difficult to reflect the law of land price change. The construction of this system makes it possible to solve this problem. The working idea of the system is from point to surface. The traditional scoring method is to score factors from top to bottom. The bottom-up thinking adopted by the system can reflect the hot areas of land price changes more comprehensively and realize land price update.
2.4 Land price early warning module
When the monitoring point land price and section land price exceed the normal change range, the land price will be warned. The warning level is divided into five levels: normal, high, high, low and low, which are represented by green, light red, deep red, light yellow and dark yellow respectively. Identifies the alarm as a field [[Warning]].
2.5 Report Design Module
Land price monitoring system involves a large number of forms, such as land price monitoring point registration form (initial/change), land price monitoring point questionnaire (annual/quarterly) and so on. The application of this system can conveniently print tables and summary reports. MapX also provides powerful support functions for map output, which can meet the needs of cartography. After the land price update is completed, it is necessary to analyze the land price law from different angles, and the visualization of map information is very important. Some scholars have done research on drawing three-dimensional land price map [13]. This system uses MapX's own thematic map drawing function to realize histogram, pie chart, density map and other thematic maps, which can intuitively and clearly prompt the law of land price and provide services for decision-making.
3 system implementation
The system is developed in an interface-driven way. The first two modules of the system are the basic functional modules of any GIS system, which mainly realize the mutual query of attribute space information and thematic map analysis through data binding of MapX, so I won't repeat them here.
The following mainly explains the coding implementation process of land price update, and the implementation mechanism of the three sub-modules is similar. Limited by space, I don't introduce the coding of specific sub-modules in detail here, but only take the section of "Land Price Update" as an example:
(1) Select the section to update: There are two methods. You can directly select the section number to update in the ComboBox control or click it from Figure 2. Click the code as follows:
Figure 2 Implementation Table of Land Price Update in Lot
Add the following code in the Plot Price Update dialog box:
Private subcommand selectqd_Click ()
Table 2. Map 1。 CurrentTool = wrong tool selection.
End joint
Add the following code to the Map 1_Selec-tionChanged () event of the main form with MapX control:
Private submap 1_SelectionChanged ()
Dim ftrsA s MapXLib。 characteristic
Dim sel As MapXLib。 select
Set sel =Map 1. Layer (lyrname). select
Set ftrs=sel.
Ftrid=ftrs。 Project (1). FeatureID
qddjupdate。 Combo 1。 Text=Ftrid
End joint
(2) After defining the section to be updated, set the monitoring point type to be selected, such as transfer, transfer and lease. Select from the drop-down box, click OK, and the number of the specified monitoring point type in the selected section will be displayed in the list box. The implementation code is as follows:
Fuzzy key point, the characteristics of ftrsA
Dim regionselin As FindFeature
Dim custLayer as a layer.
Mark I as an integer
Set regionselin=Form2. Map 1。 layers(lyr name). find . search(combo 1。 Text)
If regionselin. FindRC Mod 10 < > 1 then
Msgbox "cannot find the required layer! ″
If ... it will be over.
Set custLayer=Form2. Map 1。 Layer (combination 2. Text)
Set key =custLayer. search within feature(region selin，miSearchTypeCentroidWithin)
Set qdnpoints = key point
For i= 1 to the key point. count
List 1。 Add project points. Item (1). name
then
(3) After the qualified monitoring points in the section are selected, the average method of sample land price can be used to calculate the land price in the section. This process is easy to implement, so I won't repeat the code here.
Generally speaking, the system can realize the basic database management and spatial query analysis of GIS, the model realization of the mathematical method of land price calculation and the vertical generation of reports. According to the way of workflow, the operation of land price update is carried out according to monitoring point, monitoring section and monitoring level in turn. The system has clear hierarchy and reasonable structure, and can provide a friendly and convenient operating platform for the vast number of land management workers. The system has been applied to the dynamic monitoring of urban land price in Jinan and achieved good results.
In order to improve work efficiency and realize data sharing and interoperability, the system can consider the transition to WebGIS in the later stage. The development of e-government comprehensive platform of land and resources management department based on network GIS is an important trend of e-government development and has broad prospects.
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