Spatial Tessellations

Here you can download software, references, and documentation for generating regular tessellations of hexagons and other shaped cells for the earth as a whole, or for parts of it, as well as a tessellation used in the USGS Gap Analysis Program. These materials are for the geometric and cartographic components of such grids. There are no materials here for designing statistical samples using these grids.

The DGGRID global grid system. This software will generate tessellations of hexagons, triangles, or diamonds (pairs of triangles) for the entire earth or parts of it using a hierarchical subdivision process. This system uses C++ programs that need to be compiled and run on Unix/Linux or Apple Mac OS.

Original EMAP hexagon tessellation generating system. This system, developed starting in 1989, uses a large hexagon face of the truncated icosahedron placed on the earth to generate hexagon tessellations of various sizes. The tessellations generated by this system are limited in extent to an area of about 4500 kilometers in diameter. A large number of tessellations have been generated with this system. The programs should be compiled in C.

Original EMAP hexagon tessellation of 648 square kilometers. This equal area hexagon tessellation was originally used in the US Environmental Protection Agency EMAP program and then used in the USGS Gap Analysis Program and related applications. This grid is provided as a shapefile of polygons.  Environmental data are also available. A 40 square kilometer tessellation derived from the 648 square kilometer tessellation is available through the USGS ScienceBase Catalog.


Web Pages for Denis White
Corvallis, Oregon
email:  whitede #at# oregonstate $.$ edu