The application of wavelets to lossless compression and progressive transmission of floating point data in 3-D curvilinear grids

Many times in computational fluid dynamics (CFD) work very large datasets are produced on remote machines. This vast amount of data must often be moved to a local machine for post processing and visualization. However, this can be time consuming because of the large quantity of data that must be transmitted. Compressing the data can speed up the transmission and save several hours of the researchers' time. Progressive transmission can further increase efficiency of the visualization process by giving researchers an approximation of the data very quickly. They can then make a decision based on this approximation about whether to continue the transmission or, if the data is determined to be undesirable, to abort it. A method of lossless compression using wavelets is presented that enables progressive transmission of CFD data in Plot-3D format, a standard format for CFD data. Given a CFD data set, the floating point data is first converted to double-precision floating point format. Although the conversion to double-precision floating point numbers doubles the size of the data set, most of the extra precision retains the value of zero. It can therefore be compressed very well using Huffman codes.