Global Slope Data Record (GSDR). The surface meter-scale slopes are derived by fitting altimeter echoes from the fan-beam altimetry antenna as a function of time to Hagfors' radar backscatter model templates. The data are then re-sampled at a resolution of about 5x5 kilometers per pixel. Each GSDR image pixel is represented by a 8-bit unsigned integer. Pixels lying outside the domain of the projection are set to NoData (0). In all images, pixels with unknown or unmeasured values are also set to NoData. The remaining values are related to the slope by the following equation: DN . Original acknowledgement for data: Magellan Team, (processed by Peter Ford, Gordon Pettengill, Fang Liu, Joan Quigley)