Characterization of Landsat Thematic Mapper radiometry and geometry for land cover analysis

The Landsat 5 Thematic Mapper provides high quality imagery appropriate for a wide array of applications, including land cover characterization and classification, change detection and estimation of ecologically significant biophysical parameters. However, most of the data analyzed by the user community are not corrected for a number of prevalent radiometric or geometric artifacts, nor are the data usually corrected for atmospheric effects. Consequently, the quantitative potential of Landsat Thematic Mapper data may not be fully realized. The primary hypothesis in this project is that improvements in radiometric and geometric calibration will result in improvements in our ability to characterize the Earth´s surface. The radiometric artifacts being assessed include memory effect and scan correlated shift. Both have varying levels of impact on scene quality, depending in part upon the nature and complexity of the landscape. These artifacts have been characterized sufficiently such that they now can be removed from the imagery. While the effects of these artifacts on the imagery are relatively subtle, preliminary results indicate that they may have significant impacts upon the statistical properties of the data, which in turn may modify classification results. The geometric artifacts being investigated include those affecting band to band offsets and locational accuracy of pixels. The former artifact is being characterized in Landsat 5 imagery, and the effect on applications such as classifications and change detection needs to be quantified. It is anticipated that knowledge gained from this study will help in the radiometric and geometric processing of Landsat 7 TM data