Run expression and operation-based map drawing method

Abstract

The invention relates to a run expression and operation-based map drawing method and belongs to the technical field of vector map expression related to computer mapping. The map drawing method comprises the following steps of: (1) extracting data from a spatial database and carrying out layering organization to form a vector layer collection; (2) symbolizing each element in vector layers; (3) converting symbolized map symbols in each layer into a run collection consisting of run units; (4) carrying out superposition operation on the run units positioned on the same map raster line in a superposition order of the layers; and (5) decoding the superimposed run collection to complete map output. The map symbols in the layers of the invention are expressed by the run, thus, the method has the advantages of small occupied resources, rapid superposition operation and high map drawing efficiency; and each layer is converted into a plurality of run collections corresponding to the map symbols one by one respectively so as to improve the access speed of the map symbols in the layers and contribute to inserting and deleting operation of the map symbols.

Description

technical field [0001] The invention relates to a map forming method based on run length expression and operation, and belongs to the technical field of vector map expression related to computer graphics. Background technique [0002] With the increasing popularity of GIS application technology, the application of digital maps is becoming more and more extensive. The corresponding computer mapping methods have changed the traditional manual mapping methods, and can meet various map needs with the support of databases. The vector area map expresses the surface objects by recording the coordinates of the boundary points and the composition of the boundary, which can be regarded as recording the outline of the objects. In the drawing stage, this vector data must be transformed into raster data and output after being symbolized. [0003] The data layer of existing map mapping methods generally consists of two parts: a spatial database and a map symbol library. As the data suppo...

AI Technical Summary

Problems solved by technology

This data structure can effectively compress the raster, but it is quite inconvenient when performing other operations. The positioning, insertion, deletion, and merging under run-length encoding need to traverse the previous run-length units, which makes the efficiency of run-length operations very low. At the same time, run-length The length is expressed as an integer, which will result in low precision of the run length expression

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