Cell Indexing

A DGGS must have a method of uniquely addressing each cell. Hierarchy-based, space-filling curves, and axes methods of indexing can be used. The type of tessellation can limit the choices of indexing while the type of indexing chosen can be exploited to expose useful capabilities. Indices can provide arithmetic neighbor operations, fast linear ordering, parent-child relationships, efficient cell/tree traversal, and implied spatial tiling. Mappings between the two indexing methods is often straight forward when their DGGS models are isomorphic.

a) HEALPix DGGS indexing - Landcare New Zealand                          b) QTM indexing - Geoffry Dutton Spatial FX                                         c) the PYXIS innovation index

The PYXIS DGGS SDK provides 2 indexing methods for the ISEA3H:

  1. the PYXIS Index - a spatially compact indexing with strong parent child relationship resulting in a snowflake like fractal tile.
  2. The Rhombus Index - a UV coordinate indexing that results in a rectilinear ordered tile (rhombus shaped) and thus efficient for GPU texture mapping.