The re-gridding procedure re-maps the measured nadir and along track instrument pixels from their positions on the curved instrument scans to a uniform grid of points in the common quasi-cartesian coordinate system. The procedure uses a nearest neighbour method and retains pixels that are not used (i.e. orphan pixels), enabling retrieval of full instrument scans at Level-1C. The re-gridding procedure uses the ortho-geolocated pixel positions.
During this processing, solar and viewing angles are re-gridded on the full resolution grids for use in cloud flagging.
It should also be noted that computation of the SLSTR time parameters is included in this section. In order to comply with continuity requirements, the SLSTR time annotation file does not provide the acquisition time of each scan but the associated SSP time of each line (i.e. the time at which the satellite passes over each line). In addition, several parameters are computed that allow the retrieval of the acquisition time of each pixel.