Study On Methods Of Gradation Display Of Vector Data

With the development of Internet and information industry, GIS(short for Geographic Information System) has been widely used in variety of areas and plays an important part in people’s daily life.GIS has a variety of data sourses, including the image of remote sensing and photogrammetry, the locating data and navigation data of GPS and GNSS, as well as the product of traditional manual surveying. All these data imported to GIS can be divided into vector data and raster data. With the development of related industries, the speed of data production and updating is accelerating and data precision is becoming higher.GIS data processing system is facing a big challenge caused by big data.Existing GIS software has a mature way to display raster data. The system will produce a pyramid file when loading raster data, which enables the rapid display of zooming and browsing. However, the system cannot work in the same way when it comes to vector data. Loading and displaying large amounts of vector data still costs a lot of time. In response to this phenomenon, a number of domestic and foreign scholars have proposed feasible solutions. Of all these solutions, a typical representation is to split vector data into blocks or tiles and build a multi-level index, speeding up the display progress. With the development of network technology, correlation scholars is paying close attention to embedded GIS and mobile smart client. This paper focuses on the research and exploration of algorithm to display vector data in a gradation way.Based on these efforts, the author proposed a comprehensive way to grade vector data and explained the vector pyramid used in this paper. The vector data grading system includes an explanation of the concept, accompanied by a logical model and the physical implementation process. The following work has been done: designing methods for point, polyline and polygon data respectively, designing and implementing the interfaces and classes using object-oriented technology and the ESRI Arc Engine components, designing an index file to store the result of data classification, which can be used to recover the grading result, building a platform to load and display vector data and then test the function of extraction and grading display using experimental point data on a personal computer.The solution proposed in this paper can reduce the time when loading large amounts of vector data or zooming to a certain extent. The system can display necessary information when scaling is performed. Different grading algorithm should be applied respectively to appropriate areas according to actual needs. The system proposed in this paper can be used in existing GIS software and it may have a promising future, which plays an important role with the background of big data. At last, this paper made a summary of the efforts and achievements and proposed future directions for further research.