Mountain Grid DEM Data Compression Based on Wavelet Transform and Mixed Entropy Coding

In this paper,through analyzing the grid DEM data of mountain area in the view of informatics, it is discovered that the grid DEM data of mountain area has features of high information entropy and lower redundancy, which makes it impossible to gain high compression ratio(CR) by means of traditional lossless entropy coding method. In order to implement higher efficient compression,the authors put forward biorthogonal wavelet (with linear phase) transformation and mixed entropy coding method (Huffman coding and Run-length coding) for compressing the grid DEM data of mountain area. The experimental results prove that this method which the authors raise can not only ensure the precision of decompressed DEM data but also provide much more higher compression ratio of the DEM data.