Accuracy of geologic maps produced from Landsat data

Remote sensing techniques are now being applied to space-acquired data for use in preparing geologic maps, at least at the reconnaissance level, when maps produced from Landsat multispectral scanner data are compared with those made by conventional ground/aerial techniques, accuracies of the Landsat maps fall in the 40-60 percent range relative to their conventional counterparts. A study of map accuracy achieved with Landsat-4 Thematic Mapper (TM) data indicates a 10-15 percent improvement in this range. Results from TM scenes for Death Valley, California and the Waterpocket Fold, Utah are evaluated in this paper. While accuracy values should improve even more when corrections for topographic effects are made, there appears to be an upper limit to accuracy (not yet determined), owing to a fundamental difference between geologic maps (which show stratigraphic unit distribution below the regolith) and Landsat-derived rock units maps (which identify rock and regolith types at the surface). However, preliminary results from the Utah study indicate a marked improvement and accuracy to better than 80 percent when high spatial resolution TM-equivalent data from an aircraft mission are used.