Two-dimensional vector data compression method

Abstract

The method divides original vector data into blocks of vector data. Next, loss compression based on DCT transform is carried out for the blocks of vector data according to one of two modes. Then, entropy coding is carried out for the obtained DCT transform so as to obtain compressed blocks of vector data. Finally, all compressed blocks of vector data are organized as binary bit steam in specific format. Main effects of the invention are: compression ratio near to 20 is reached for vector data formed natural in wide range such as contour line, road network and water system etc; SNR reaches to 60dB; and maximal absolute deformation is about 10-5 order of magnitude of dynamic range of original vector data. Features are: controllable distortion generated in reconstructing error and compression process; providing technical base for asymptotic transmission of vector data flexibly and in high efficiency by combining asymptotic compression technique in space domain and in frequency domain.

Description

technical field [0001] The invention relates to the field of information processing, in particular to a method for compressing two-dimensional vector data. Background technique [0002] 1. The characteristics of two-dimensional vector data in GIS and the necessity of its compression: [0003] Two-dimensional space vector data is one of the main data types managed and applied by the current geographic information system, which has the characteristics of large data volume, uneven distribution, and complex topological relationship. Vector data in GIS is generally expressed in the form of coordinate strings, and the coordinate data is generally in floating-point format. With the improvement of the ability to obtain data and the user's requirements for data accuracy, in order to better express the real geographic world, the amount of GIS vector data It is extremely large and requires a lot of storage and transmission resources. In emerging GIS application fields such as geograp...

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Problems solved by technology

[0012] 3. Quantization and distortion of two-dimensional vector data compression:

For the above problems, researchers have not yet proposed a complete solution. They are only involved in the research on spatial databases, spatial data network services, WebGIS, etc., but no in-depth research has been carried out, let alone a systematic method.

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