Compressed Storage and Publishing Method for Tiled Raster Maps

Abstract

The invention discloses tile type grid raster map compression storage and release methods. The compression storage method comprises the steps of displaying a feature type for a tile image, and dividing the tile image into an incompressible tile containing a ground object and a feature tile only with land or water surface; when a map rendering tool cuts the image to generate the tiles, performing image detection, feature classification and marking on each tile, and storing the tiles as index files; and storing the map tiles, directly outputting and storing the incompressible tile, and not outputting and storing the feature tile. The release method comprises the steps of quickly retrieving and reading out feature codes corresponding to the tiles from the index files; and releasing the feature tile by directly adopting the land feature tile or the water surface feature tile, and releasing the incompressible tile by using corresponding original tile image data. According to the methods, a feature index table is established; a large amount of repeated redundant tile data is deleted; the tile quantity and the storage space required for map display are greatly reduced; the release efficiency is effectively improved; and the display performance is almost not influenced.

Description

technical field [0001] The invention relates to a method for compressing, storing and publishing tiled grid maps. Background technique [0002] WebGIS (Web Geographic Information System) is the combination of the Internet and GIS technology. WebGIS technology enables users to obtain a large number of practical personal location services through web browsers, and can transmit spatial information to thousands of households through the network. The basic core function of WebGIS technology is fast and exquisite map browsing and display. [0003] Online map services usually use tiled raster images of 256x256 or 300x300 pixels, and commonly published raster images are in PNG, JPG, or GIF format. Tiles and tile images are small images of uniform size and format cut by a special agreed method, and the width and height of tile images are generally 256 pixels. The tile data of the grid map ranges from 0 to n levels (n is usually 17 to 23, that is, the grid map has 18 to 24 scale lev...

AI Technical Summary

Problems solved by technology

[0019] However, no matter the image compression method or the image color reduction method is for the processing of the tile image data itself, the number of tiles will not change before and after processing, so the existing technology partially solves the problem of the size of the tile data transmission, but for Solving the storage space problem of tile data on the server side is not effective

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