Comparison of tasselled cap components of images from Landsat 5 Thematic Mapper and Landsat 7 Enhanced Thematic Mapper Plus

Use of the tasselled cap transformation (TCT) is widely accepted in the remote sensing community, but there is concern whether the TCT components from each unique tasselled-cap-like feature space from different sensors are directly comparable. This study compared the differences of the TCT components from Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced TM Plus (ETM+) images with different TCT coefficients from paired images. The results demonstrated that time series analysis of Landsat images using the TCT components derived from Landsat 5 TM and Landsat 7 ETM+ digital numbers (DNs) or at-satellite reflectance could introduce errors. Through converting Landsat 5 TM to Landsat 7 ETM+ DNs prior to the TCT transformation, the RMSEs were reduced by >62 percent. Overall, it was better to derive the TCT components from at-satellite reflectance images, normalised by relative radiometric correction, based on the TCT coefficients for Landsat 7 ETM+ at-satellite reflectance.