Processing description

The service takes as input SWH-1A product and generates standard ortho-rectified on DEM product (SWH-2A-Carto products) where the altitude and spatial resolution are set up by the processing in a cartographic projection. A metadata file is added to the product. If a pair of SPOT 5 THR images is provided as input, a supermode processing (fusion of two images at 5 m GSD to compute a more resolved image at 2.5m GSD) followed by a deconvolution (reduction of blur) processing are performed. (Latry C. and Rougé B., 1998)
Ortho-rectification takes only a few seconds to process, supermode+deconvolution takes between 3 and 4 minutes.Processing
Christophe Latry and Bernard Rouge "SPOT5 THR mode", Proc. SPIE 3439, Earth Observing Systems III, (3 October 1998); https://doi.org/10.1117/12.325654

Product description

Input product: SPOT Level 1A

Radiometry:
· Detectors normalization applied (dark current offset and sensitivity gain)
· 8 bit coded – instrument digital counts (no calibration)
Geometry:
· No geometrical correction
· Each line corresponds to a full detector array acquisition (square image)
· Pixel resolution not consistent in the field of view (specially for oblique viewing)

Output product: SWH Level 2A-Carto

Radiometry:
· 8 bit coded – instrument digital counts (no calibration)
Geometry:
· Data is projected in UTM projection using a world DEM (1km GSD)
· Product orientated with respect to the geographic North
· Pixel resolution is fixed, defined by the sensor and the satellite

SatelliteChannelSpatial resolution
SPOT 1 to 4PAN10 m
XS20 m
SPOT 5PAN5 m
XS10 m
THR (supermode)2.5 m

· As no GCPs are used in the processing location, performance corresponds to the initial one of the products:
· About 500 m (RMS) for SPOT 1/2/3
· About 200 m (RMS) for SPOT 4
· About 50 m (RMS) for SPOT 5

Metadata description

Metadata file in xml format contains:
· Data georeferenced Product characteristics (satellite, sensor, acquisition date product level…),
· Image Georeferencing in cartographic projection frame,
· Corners coordinates in cartographic projection and geographic frames (WGS84),
· Solar (SZA) and View (VZA) zenith and azimuth angles,
· Gains and offsets for reflectance conversion.