Correction of Radiometric Steps at Dual-Sensor Imaging Spectrometer Detector Joints.

Airborne and spaceborne hyperspectral imaging typically relies on dual-sensor systems in order to cover the visible and near-infrared (VNIR) range and the short-wave infrared (SWIR) range simultaneously. One often overlooked imaging side effect of such systems is the spectroradiometric step at the joint of the VNIR and SWIR detectors: the magnitude of such a step varies depending on the target but is particularly noticeable after reflectance retrieval. This spectral discontinuity becomes a source of error when conducting a full-spectrum analysis such as spectral unmixing based on continuous laboratory endmember spectra. We show that a step correction is preferable by comparing the goodness of fit and the Spectral Angle Mapping (SAM) of two data sets before and after applying the correction. We also demonstrate that it is necessary to apply the radiometric correction after atmospheric compensation rather than correcting the effect on the raw radiance data.