Configuring Area Definitions

SIFT allows only map projections which are provided by configuration via Satpy. All or some of them must be “activated” for use by configuring area_definitions as follows:

area_definitions:
  [DISPLAY_NAME_AREA_GROUP_1]:
    {
      [DISPLAY_RESOLUTION_IDENTIFIER_1_1] : [AREA_ID_1_1],
      [DISPLAY_RESOLUTION_IDENTIFIER_1_2] : [AREA_ID_1_2],
      ...
    }
  ...
  [DISPLAY_NAME_AREA_GROUP_N]:
    {
      [DISPLAY_RESOLUTION_IDENTIFIER_N_1] : [AREA_ID_N_1],
      [DISPLAY_RESOLUTION_IDENTIFIER_N_2] : [AREA_ID_N_2],
      ...
    }

where DISPLAY_NAME_AREA_GROUP_i is the name to be used in the GUI to refer to the area group. Each DISPLAY_NAME_AREA_GROUP_i represents a group of areas that share the same projection but have different resolutions. Therefore, within a single area group, there are one or more areas organized in a key-value structure. The key denotes DISPLAY_RESOLUTION_IDENTIFIER_i_j, which is used in the GUI to represent resolutions for the selected area group. The value represents AREA_ID_i_j, by which a specific area definition is reached. Area ID AREA_ID_i_j must be provided by according Satpy configuration (unknown area ids are skipped with a warning log message).

The area groups appear in the Projection: picklist in the same order they are listed in the area_definitions configuration, with the first entry selected at application start. The resolution identifiers appear in the Resolution: picklist in the Open File Wizard window based on the selected projection (area group). They are listed in the same order as within a single area group in the area_definitions configuration, and by default, the first resolution identifier entry is selected. In this way, the user has the possibility to select the projection and the resolution and based on that the area ID is determined.

One additional area definition is appended as a fallback by SIFT if no area definition or none with a pseudo lat/lon projection (Plate Carree) is found. This is to make sure there is always a projection showing the whole world selectable in the application, which is useful for examining data of a yet unknown area.

Example:

area_definitions:
  MTG FCI FDSS:
    {
      1km: mtg_fci_fdss_1km,
      2km: mtg_fci_fdss_2km,
      500m: mtg_fci_fdss_500m,
      32km: mtg_fci_fdss_32km
    }

  MSG SEVIRI FES:
    {
      3km: msg_seviri_fes_3km,
      1km: msg_seviri_fes_1km,
      9km: msg_seviri_fes_9km
    }