A DEM can be represented like an image, except that it contains a single channel of information of various shades of grey and can be compressed in a lossy or lossless manner by way of existing imagecompression protocols. Compression has the effect of reducing memory requirements and speed of transmission over digital links, while maintaining the integrity of data as required. In this context, this paper investigates the use of an alternative image pyramid approach for DEM lossless compression referred to as Pyramid Lossless Differential Coding (PLDC).
The effect of the PLDC on floating-point elevation values for 16-bit DEMs of dissimilar terrain characteristics is investigated here. Tests demonstrate that the compression ratios and compression speed achieved with this approach can be comparable to, or better than, lossless proprietary JPEG variants and other image formats (i.e. PNG, TIFF).