The radiometric normalization of multitemporal Thematic Mapper imagery of the midlands of Ireland - a case study

Abstract

Two Landsat Thematic Mapper (TM) scenes of the same area of the midlands of Ireland were required to be radiometrically normalized. Standard techniques were reviewed and considered unsuitable. A hybrid approach was adopted that used linear transformation functions. As part of this approach, a novel thresholding-based method for extracting reference data from a land cover class with sub-pixel scale elements was developed. This method was shown to be robust with a consistency of ca - 1 digital number (DN) being achievable in the extracted reference data. A procedure for removing pixels influenced by thin cloud and associated shadow was included. The radiometric normalization approach produced acceptable Root Mean Square Errors in the range 0.8-2.5 DN. Whereas the strategies and methodologies developed were appropriate to the particular environment, the developmental process may serve as a template for analysts working in similar environments elsewhere.