(1. Shaoxing Land and Resources Information Center, Shaoxing,101400; 2. Shanghai Tongji University)
Using geographic information system (GIS) to construct cadastral management information system can accurately reflect the spatial characteristics of land, and its advantages are beyond doubt. However, the cadastral files are large, the error rate is high and the input intensity is quite large. This paper will focus on the analysis and research on the processing methods of historical ownership information based on GIS cadastral management information system, and put forward a set of efficient processing methods.
Keywords: geographic information system; Cadastral management; Ownership information
Cadastral management information system is the largest and most extensive business in land and resources management, and it is also the most basic business, occupying a very important position. Cadastral management information system is essentially composed of two parts: land spatial attribute and cadastral ownership attribute. Essentially, GIS system solves the expression of spatial attribute data. To build a complete cadastral management information system, cadastral ownership information must be added.
1 general implementation method of cadastral management information system
Cadastral management information system is based on massive land spatial data and attribute data. Cadastral data information is usually obtained through actual cadastral survey, and the relevant departments organize special personnel to investigate the corresponding plots to obtain information such as location, boundary, quantity, quality, ownership and use of the plots. The main steps include land survey, electronic map establishment and attribute data entry.
1. 1 land survey
Surveyors conducted field surveys on the land in this area to obtain first-hand spatial data about the land. Land survey is divided into basic survey and daily survey. Basic survey is a comprehensive survey of the land in the region to obtain complete basic data, which is the basic work of the whole cadastral management information system. However, the basic investigation consumes huge human and financial resources and cannot be carried out frequently. It must be carried out irregularly according to the degree of terrain change to ensure that the basic information can truly reflect the actual terrain. Daily survey is some geographical and cadastral elements that need to be supplemented in land registration and certification, and it is a supplement to cadastral information.
Establishment of 1.2 electronic map
The establishment of electronic map has the following four steps:
(1) Establish a basic electronic map using basic survey data. Using special surveying and mapping software to make and edit surveying and mapping data can initially establish an electronic map based on surveying and mapping standards. However, the electronic map based on surveying and mapping standards is not divided into layers, and points, lines and surfaces all exist, which can not be directly used as GIS spatial data, but constitute the basis of GIS spatial data.
(2) Generate GIS layers from basic electronic maps based on surveying and mapping standards, and extract various layers, which are divided into three categories: points, lines and areas. The most important work is to establish regional map layers and other auxiliary layers.
(3) Cadastral mapping combines cadastral elements with geography to create blocks, streets, boundary points and other elements.
(4) Revision Work According to the actual needs, the GIS layer is revised to make it conform to the cadastral work standards.
1.3 cadastral attribute data processing
Cadastral attribute data processing involves the following two aspects:
(1) Establish the spatial relationship between cadastral map layers.
(2) Enter other attributes of cadastre.
The input of existing attribute data can be synchronized with the issuance of certificates, but the biggest problem is the processing of historical data.
2 problems and countermeasures in the implementation of cadastral management information system
2. 1 Main problems in the implementation of cadastral management information system
(1) Insufficient integrity of cadastral system At the initial stage of the establishment of cadastral management information system, the biggest problem was the insufficient integrity of parcel map layers. Because although a complete parcel map layer has been established, there are few existing cadastral data and cadastral information associated with the layer, most parcels have no cadastral information association, and a lot of historical cadastral information is outside the parcel map layer.
(2) The incompleteness of the parcel map layer brings great inconvenience to the actual work, and it is difficult to find and correct the incorrect and conflicting geographical information by manual operation.
(3) It is very difficult to process cadastral historical information. The historical information of cadastre is mainly stored in cadastral files, and the number of files in cities and counties (cities) will generally reach hundreds of thousands of volumes. At the same time, it is also very serious to solve the problem of data errors in historical data. According to actual statistics, the error rate is as high as 40%.
2.2 Several aspects that should be paid attention to when solving problems
(1) Pay attention to the historical information processing of cadastre. In the process of establishing cadastral management information system, we must pay attention to the construction of cadastral historical ownership information besides the construction of spatial database.
(2) Research on processing methods to improve the processing efficiency of cadastral historical information.
3 Cadastral historical data processing method and practice
Efficient cadastral historical data processing includes three stages, as shown in figure 1.
Figure 1 cadastral historical data processing flow
The first stage is to digitize files, extract and establish preliminary basic data; The second stage is data cleaning, which exports basic data from the archive database, carries out necessary processing and establishes an index; The third stage imports the cleaned data into the cadastral database.
3. 1 file digitization
Archives are the source of cadastral historical data, but paper archives are not suitable for automatic and efficient information processing, and must be digitized, but the focus of processing is not to scan documents into pictures, but to extract valuable attribute data.
Archives digitization is the forerunner and basic project to process historical cadastral information, mainly to extract valuable attribute data; On the other hand, we can check and proofread the correctness of the data and unify the data format. Because of historical reasons, the standards of many data have changed greatly and must be revised.
Archives digitization itself has a huge workload, and the establishment of high-quality archives database is of great significance to cadastral management information system, and to some extent, it is the leading work of cadastral management information system.
3.2 data cleaning
Archives data cannot be directly used as cadastral attributes, and cadastral attribute data must be absolutely correct, because it will directly affect the correct rate of issuing certificates. Therefore, there must be a strict proofreading system, and even when issuing certificates, it is checked by computer, so it must be cleaned up. Therefore, the archived data is exported to the intermediate database, which facilitates data cleaning.
(1) Graph number combination mainly checks and converts the format of ground numbers, which are the link between attribute data and spatial data. The accuracy of ground figures is very important, which directly leads to the correct matching of attribute data and spatial geographic data. At the same time, make full use of GIS system, and use the method of combining figures and numbers to check the spatial correctness.
(2) Making extended cadastral attributes means that the obligee has the same economic indicators in the same parcel, and then extracts and standardizes them separately, thus making sub-parcel attributes.
3.3 The use of cadastral attribute database
After importing the cleaned data into the cadastral attribute database, the use of the cadastral attribute database is also very important.
(1) Establish a cadastral index. Through the cadastral index, the staff can conveniently retrieve and view the development, ownership, use and other attribute information of the corresponding plots according to the number and other information of the investigated plots; At the same time, cadastral index can also be used as the basis of historical cadastral registration information, thus greatly reducing the time and energy spent on cadastral information search and verification in the specific operation process.
(2) Establish a parcel ledger.
Cadastral is the foundation of land management, and the establishment of cadastral management system based on GIS plays a decisive role in the scientificity and accuracy of land management. However, due to various reasons, people always pay more attention to the construction of spatial data, but often ignore the construction of attribute data, and attribute management is the core of cadastre. The above practice is actually a verification of the work of Shaoxing Land and Resources Information Center in the construction of cadastral management information system in recent years, hoping to play a role in attracting jade.
refer to
Editor-in-Chief Wu Lun. Geographic information system-principles, methods and applications. Beijing Science Press 2004.
Editor ye. Cadastral management. Beijing China Agricultural Press 2002.
Fan Zhiquan. Cadastral survey. Beijing: China Agricultural Publishing House, 2004.
Zhan Changgen, Tang Xiangyun, Liu Li. Cadastral survey. Wuhan: Wuhan University Press, 2005.