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Vector data compaction and compression method and corresponding decompression method

A technology of vector data and compression method, which is applied in the field of geographic information systems, can solve the problems of no calculation method, the influence of offset compression effect, and not being widely used, and achieve the effect of effective simplification and compression

Inactive Publication Date: 2009-10-21
CHINESE ACAD OF SURVEYING & MAPPING
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Problems solved by technology

[0007] The downside of Douglas-Peucker's streamlined approach is that the setting of its tolerances cannot be automated, requires human intervention, and there is no convincing calculation of how its tolerances should be set so that there is no "visual error"
In the offset compression method, since it is not "mapped" to the short virtual screen, but directly rounded to an int coordinate, the offset of most adjacent points on the curve may not be within ±127. Therefore, most of the offsets use short type instead of byte type, which greatly affects the effect of offset compression, so it is not widely used

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  • Vector data compaction and compression method and corresponding decompression method
  • Vector data compaction and compression method and corresponding decompression method
  • Vector data compaction and compression method and corresponding decompression method

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Embodiment Construction

[0063] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0064] In a specific embodiment of the present invention, the steps of simplifying and compressing the vector data are as follows.

[0065] (1) After reading in the vector data, determine the size of the virtual screen.

[0066] The user needs to browse the map on the computer, so it is necessary to map the space point coordinates represented by float type or double type in the geodetic coordinate or paper coordinate system to a virtual screen coordinate system represented by short type or int type, namely Including mapping float or double type coordinates to short type or int type virtual screen. Then, after reading in the relevant geographic information vector data, it is necessary to first determine the size of the virtual screen, and then set the corresponding mapping range accordingly. Among them, 65536 is a jump point of the pr...

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Abstract

The invention relates to the technical field of geographical information systems and provides a vector data compaction and compression method based on virtual screen mapping theory as well as a corresponding decompression method. The vector data compaction and compression method includes the following steps of: determining the size of a virtual screen; conducting Douglas compaction on segmental arc coordinate; conducting virtual screen mapping on the coordinate; conducting offset storage and compression on the segmental arc coordinate; and packing data after compaction and compression and conducting general lossless compression. The methods can be widely applied to the vector data compaction and compression in the fields of GIS, Web, GIS, MovingGIS and car navigation, and can compact and compress the volume of vector data dramatically on condition of meeting visual fidelity.

Description

technical field [0001] The invention relates to the technical field of geographic information systems, in particular to a vector data simplification and compression method and a corresponding decompression method based on a virtual screen mapping theory. Background technique [0002] The simplification and compression of vector data is one of the classic technical problems of geographic information science. The simplification and compression of vector data are two different issues that are both different and related. Data reduction refers to extracting a representative subset from the original data set, which can basically express the information expressed by the original data set. Data compression generally refers to a certain transformation of the data set to form a new data set. The new data set has a smaller amount of data, but it can also express the information expressed in the original data set. [0003] Generally speaking, data reduction does not change the organiz...

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Application Information

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IPC IPC(8): G06F17/30
Inventor 李青元刘晓东边丽华宋妍颖刘纪平张福浩陶坤旺王涛
Owner CHINESE ACAD OF SURVEYING & MAPPING
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