The massive multi-temporal land use data stored in the database of the basic land use information system is generally obtained by means of map digitization, and the accuracy and quality of the digitized data directly affect the reliability of the application analysis of the system and the realization of the application target, and affect the land use. Daily management. In the process of map digitization (scan vectorization) and GIS data collection and database construction, the land use area and the legal registration area are different due to the systematic error of the land area measuring instrument and the error in data collection. The area where the land has been registered is also obtained by a certain measurement method, and the area value also has an error. How to eliminate or reduce the impact of these errors and ensure the accuracy of land use area is one of the key issues in the database construction of GIS systems. When the Changchun Municipal Bureau of Land and Resources conducted the land use data GIS to build a database, it encountered a problem of using the digital method to obtain the land area of ​​the land parcel and the legal registration area. If the error processing is not carried out, it will have a certain impact on the daily management work. The role of GIS cannot be fully utilized. In response to this problem, this paper proposes an area processing method and prepares an area error processing software to ensure the accuracy and quality of the database data.
Area error processing:
1. Area Adjustment of Independent Blocks For some independent and single plots, since the plots are not related to each other, the conditional equation can be directly used for adjustment.
2. Overall adjustment of multi-block area In the process of digitizing land use area, a region (a block) is a collection of relatively independent areas composed of many adjacent blocks without gaps. Due to the presence of multiple parcels, multiple area error condition equations are generated and the plots are interrelated. If each plot is individually adjusted, regardless of its correlation, the result of the adjustment is that the boundaries between adjacent blocks are not completely coincident, so that there are gaps or intersections, the adjustment calculation has no use value, and the phase is destroyed. The adjacent relationship between neighboring blocks cannot be sent to the GIS library.
Therefore, it is necessary to carry out the overall processing of multiple parcel areas, form the conditional equations to make the adjustment uniformly, and calculate the correction number of the digital coordinate observations of the vertex of each block and the corresponding flat difference value by the adjustment calculation. When the amount of observation data is particularly large, the land area grading adjustment processing can be employed.
According to the problem of the difference between the area of ​​the digital plot and the legal registration area when the land use data of the Changchun Municipal Bureau of Land and Resources was built, the adjustment model of the area error was established. The calculation and analysis of the example showed that the area error condition was established. The equation is adjusted to eliminate the difference between the land registration area and the digitized area value, and to ensure the consistency of the topological relationship between the blocks. For the treatment of the parcel area by using the known area as the observation value, it is necessary to further explore the difference between the digitized area and the legal registration area.
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