Spatial Vector Data Compression Method Based on Integer Wavelet Transform

The curve vector data are characterized by small differences between coordinate values of adjacent points.So in this paper,differences between the coordinate values are converted to the integer offset and then the offset is used as the substitute for coordinates of vector data.The integer offset sequence is processed by integer wavelet transform and then lossless entropy coding is used to compress the wavelet coefficients.Compressing the China's digital geographic map data of SHP files by the presented method generates a compression ratio higher than 11.Experimental results show that,for the vector data lossless compression,the presented compression method can achieve a higher compression ratio than other similar methods.