基于小波变换的数字地图数据压缩技术研究

Study on Wavelet Transform Based on Digital Map Data Compression

针对数字地图数据的特点 ,提出了一种基于小波变换的数字地图压缩方法。文中主要研究了小波滤波器的选取、标量量化、自适应算术编码、压缩文件存储格式等问题 ,并就在给定精度要求的前提下如何获得最大压缩比的问题进行了深入研究。文末应用该方法对 5种不同类型的数字地图数据进行了压缩与解压缩测试。结果表明 ,该方法与其他方法相比较 ,能够在相同失真的情况下产生更大的压缩比。

The digital map data compression technique is one of the keys to digital map technique. In this paper, a wavelet transform based digital map data compression algorithm, according to the characteristic of elevation data, is presented. And some relevant key techniques including choice of wavelet, uniform quantizer with dead zone, adaptive arithmetic coding and compression file structure are also emphatically studied. This paper also proposes a new error allocation algorithm, capable of efficiently allocating a given quota of root of mean square (RMS) error to a set of different quantizers, which is very important for the practice of digital map data compression. Finally, the compression and the decompression tests are carried out for five different kinds of digital maps. Experimental results show that the technique can achieve higher compression ratio with the same given quota of RMS error compared to other compression algorithms.