Rasterization (ie interpolation on image grid) from geolocation needs homogeneization among params

[agrouaze]

the geolocationGrid annotations contains several fields: ['longitude', 'latitude', 'height', 'azimuth_time', 'slant_range_time','incidence','elevation'] Currently they all use a method for decoding : geolocation_grid expcet elevation & incidence that use annotation_angle method. These methods don't return the same type of object. It is something that is important at the rasterization step in sentinel_dataset.py. This issue has already been addressed in PR #38 but it will be effectively merge from a future PR dedicated to this rasterization step.

• [ ] change func in senitinel_xml_mappings.py for elevation and incidence
• [ ] add elevation and incidence in the s1meta.geoloc xarray
• [ ] homogeneize the method in sentinel1_dataset.py to get the HR variables described in geolocationGrid annotations.

[oarcher]

from work done in #46, related to #42