Seamless wavelet pyramid construction for raster data
无缝栅格数据小波金字塔构建

A raster data pyramid is a basic data structure in spatial information systems.The boundary issue caused by blocking must be considered in a wavelet-based pyramid construction method.This issue is not mentioned in most existing algorithms or a large amount of calculations is needed to eliminate the border gap in those other methods.This paper presents a wavelet coefficient stitching algorithm for data blocks,which addresses the block boundaries in the wavelet transformation.The key point of our stitching algorithm is that one block coefficients is patched by its adjoining blocks boundary coefficients.The stitching result is equivalent to proceeding wavelet transformation on the whole data.A pyramid construction method is proposed that is named seamless wavelet pyramid construction method (SWPCM).In the SWPCM,the whole data is divided into a large number of blocks and a wavelet transformation is performed on each block.Then,the stitching algorithm is executed on the blocks' wavelet coefficients.The boundary coefficients are eliminated and data seamless organization is achieved with SWPCM.The experiments show that the stitching algorithm can significantly reduce the sizes of high level coefficients and that the proposed method is easy to implement.