IGEO7 DGGRS Provider

The DGGRS provider IGEO7Provider uses dggrid4py (>=0.5.2) and dggrid (>=8.4.1) to generate hexagonal DGGRS using the IGEO7 indexing schema.

Initialisation parameters

The initialisation parameters parameters provided in the dggrs table are stored in the self.properties object that belongs to the IGEO7MetafileConfig class.

The IGEO7MetafileConfig stores dggrid metafile configuration. Currently, it supports the following parameters(default values) for metafile configurations:

# Z7 index schema setting
input_address_type: str = 'HIERNDX'
input_hier_ndx_system: str = 'Z7'
input_hier_ndx_form: str = 'DIGIT_STRING'
output_address_type: str = 'HIERNDX'
output_cell_label_type: str = 'OUTPUT_ADDRESS_TYPE'
output_hier_ndx_system: str = 'Z7'
output_hier_ndx_form: str = 'DIGIT_STRING'
# initial vertex lon setting
dggs_vert0_lon: decimal.Decimal | float | str = 11.20
# The following parameters are included to let users know what value is used.
# It should not be channged.
dggs_vert0_lat: Final[decimal.Decimal | float | str] = 58.28252559
dggs_vert0_azimuth: Final[decimal.Decimal | float | str] = 0.0

WGS84 Geodetic Coordinates System

IGEO7Provider supports conversion between authalic and WGS84 geodetic coordinates. It is controlled by the crs of the dggrs. The conversion is enable if and only if the crs == wgs84. When it is enabled, the provider performs the conversion for both input coordinates and output returns.

Example of parameter settings

enable WGS84 geodetic conversion and use 11.20 for the dggs_vert0_lon by default

"dggrs": {"1":
     {"igeo7":
        {"title": "IGEO7 DGGRS with z7string",
         "description": "Hexagonal grid with ISEA projection and refinement ratio of 7. z7 space-filling curve",
         "crs": "wgs84",
         "shapeType": "hexagon",
         "definition_link": "https://agile-giss.copernicus.org/articles/6/32/2025/",
         "defaultDepth": 1,
         "classname": "igeo7_dggrs_provider.IGEO7Provider"
         }
    }
}

manually set the dggs_vert0_lon to 11.25 and disable WGS84 geodetic conversion

         "dggrs": {"1":
         {"igeo7":
             {"title": "IGEO7 DGGRS with z7string",
              "description": "Hexagonal grid with ISEA projection and refinement ratio of 7. z7 space-filling curve",
              "crs": "authalic",
              "shapeType": "hexagon",
              "definition_link": "https://agile-giss.copernicus.org/articles/6/32/2025/",
              "defaultDepth": 1,
              "classname": "igeo7_dggrs_provider.IGEO7Provider",
              "parameters": { "dggs_vert0_lon": 11.25 }
             }
         }
     }