Research On Key Technologies Of WebGIS Based On Vector Tiles

With the development of geographic information system and Internet technology,the network geographic information system(WebGIS)is developing rapidly.In the big data era,the network of traditional geographic information system faces many shortcomings,figure out the low efficiency and slow rendering,how to achieve efficient data transmission using the problems that hinder the further development of network geographic information system.The emergence of HTML5 technology,especially Canvas and other new technologies,has brought forward a new solution for the development ofgis.Tile based transmission mode,effectively improve the efficiency of data transmission in WebGIS,tile data mainly includes two kinds of grid tiles and vector tiles.The use of a wide range of grid tile technology.When using the grid tile technology,the client is the processed picture,can not be further analyzed.Vector data can meet the client’s data analysis and interaction.This research adopts the transmission mode vector tiles in WebGIS,through the study of vector tiles in WebGIS storage,visualization,indexing,caching strategy to construct the overall solution vector tiles based on WebGIS program,the whole process,to achieve vector tiles in WebGIS efficient transmission and visualization.Compared with the WebGIS based on the grid tile,the tile can realize the tile map interaction on the basis of the transmission efficiency.Based on the solution,HTML5 and VUE framework are used to build an application example of WebGIS.In this paper,we focus on the problem of cache replacement strategy of the tile on the client side when the data is too large and the response time is too long.In this paper,a cache mechanism is built on the client side,and the tile cache index is constructed.The GUH cache replacement algorithm and VEAT cache replacement algorithm are proposed.Compared with the experimental results,the two algorithms proposed in this study have a great advantage over the traditional algorithms in terms of tile hit rate and byte hit rate.Among them,the GUH algorithm is more suitable for small and medium scale Pyramid tile map operation,VEAT algorithm in the case of small cache capacity advantage.