BOA Reflectance Based Dead and Defective Pixel Interpolation in the ENMAP Ground Segment Processing Chain

Kurzfassung

The high-resolution imaging spectroscopy remote sensing mission "Environmental Mapping and Analysis Program" (EnMAP) [1] was successfully launched on April 1st, 2022 and entered operational phase on November 2nd, 2022. The data acquired by remote sensing platforms might be affected by different types of pixel defects, due to aging, degradation of electronic components, mechanical vibrations and data transmission failures [2]. These can produce from missing to low quality data (i.e. low- and high-gain linearity effects, non-uniformity effects (photo-response non-uniformity (PRNU), dark-signal non-uniformity (DSNU)) as well as low and high radiance values outside of the allowed dynamic range). In addition, sensor noise can reduce the quality of the data in some pixels in strong atmospheric absorption spectral regions. In particular in strong atmospheric absorption regions the narrow spectral bands may suffer from low signal to noise values. This paper gives a description of the dead and defective pixel correction algorithm as implemented in the EnMAP L1B processor. Results are evaluated intrinsically by generating artificial dead-pixel maps, masking healthy nominal pixels of an acquired EnMAP datatake in order to be able to compare the interpolated results with valid reference values. Further interpolation results are extrinsically and quantitatively compared to the dead-pixel interpolated processor output of the DESIS hyperspectral sensor, for which dead-pixel correction is conducted by common means of interpolating in spectral dimension on top-of-atmosphere (TOA) radiances and only on hardware-based defects (in contrary to the EnMAP dead and defective pixel masks which includes quality flagging). Additionally, the dataset is artificially damaged to simulate partial loss of the radiance data to present the overall performance of the dead-pixel correction reconstruction capabilities within the frame of the file and data deletion conditions.