Encodes point data into the DGGS JSON schema.

A DGGS JSON dataset consists of a top zone whose boundary encompasses all the point data and a full set of subzones one or more zoom levels down from the top zone. Each subzone conatins a single set of values for that location. This is conceptually similar to raster data, where the top zone is the raster extents, and the subzones are the pixels.

The transformer will group the source points by subzone and calculate the user's choice of mean, median, minimum or maximum to assign to the value of the subzone.

How does it work?

The DGGSJSONEncoder uses the open source dggal library to generate the top zone and subzone cells. To install the library, please follow the instructions on Installing Python Packages to FME Form to run the following install:

fme python -m pip install dggal

This library provides an interface to the following Discrete Global Grids:

GNOSIS Global Grid

Icosahedral Snyder Equal Area Hexagonal 3 (ISEA3H)

Icosahedral Snyder Equal Area Rhombic 9 (ISEA9R)

Icosahedral Vertex-oriented Great Circle Equal Area Hexagonal 3 (IVEA3H)

Icosahedral Vertex-oriented Great Circle Equal Area Rhombic 9 (IVEA9R)

Rhombic Triacontahedron Equal Area Hexagonal 3 (RTEA3H)

Rhombic Triacontahedron Equal Area Rhombic 9 (RTEA9R)

rHEALPix Global Grid

Discrete Global Grids partition the earth into a hierarchical set of polygons which can be denoted by unique identifiers, with the size of the polygon decreasing and the number of polygons incereasing as the level increases. Depending on the grid chosen, polygons can be hexagonal, rectangular or rhomboid.