These files contain the Nested Hexagon Framework (NHF) developed by Mike Houts at the University of Kansas, along with NatureServe's extensions. The NHF is a fishnet grid of one square mile hexagons covering most of North America. It aggregates hexagons together to create 7 square mile "cogs" and 49 square mile "wheels". We have extended the geographic coverage to include northern Canada, the Caribbean, Central America, Hawaii, and Bermuda. We have also created additional hexagon layers that further aggregate these features to broader scales:

Level 1 Summary Hexes - aggregates wheels into 343 square mile features
Level 2 Summary Hexes - aggregates Level 1 Summary Hexes into 2,401 square mile features
Level 3 Summary Hexes - aggregates Level 2 Summary Hexes into 16,807 square mile features


======================
Esri File geodatabase
======================

nested_hexagon_framework_1sqm.gdb.zip contains a file geodatabase with the following layers:

nhf_hexes
nhf_cogs
nhf_wheels
nhf_wheels_smoothed
nhf_hexes_na - our north american extensions
nhf_cogs_na
nhf_wheels_na
nhf_wheels_smoothed_na
nhf_summary_hexes_l1
nhf_summary_hexes_l2
nhf_summary_hexes_l3
grid_5deg_nhf_coverage - this shows the 5 degree grid zones covered by the original framework, our custom extensions, and those which are not covered by either.

These layers were created by exporting data from the postgres database to an Esri file geodatabase and adding attribute indexes for the hexagon/cog/wheel/grid ID fields. grid_5deg_nhf_coverage is an exception; it originated from an Esri file geodatabase and was separately added.

exportNHF.bat is the batch script used to export data.

addIndexes.py is the arcpy script used to add the attribute indexes.

NHF_Extensions.mxd can be used to visualize the geodatabase layers.

NHF_Extensions_wm.mxd is the same map, but projected to web mercator. It is intended to give an idea of how data will look through a web map.

======================
PostGIS database
======================

nested_hexagon_framework.pgdump.bak is a postgres custom-format database dump created using pg_dump which contains the following tables:

nhf_hexes
nhf_cogs
nhf_wheels
nhf_wheels_smoothed
nhf_summary_hexes_l1
nhf_summary_hexes_l2
nhf_summary_hexes_l3
grid_5deg
grid_5deg_nhf_coverage

Postgres was used to extend the core framework. See https://softwaredev.natureserve.org/confluence/display/NSX2/Extending+the+Nested+Hexagon+Framework+coverage for details.

The grid_5deg table contains the 5 degree grid zones projected to 102039 (USA_Contiguous_Albers_Equal_Area_Conic_USGS_version). However, prior to projecting the geometry, vertices were inserted every 200 meters in order to better preserve the true boundaries of the zones.

select
  objectid, st_transform(st_segmentize(geography(shape), 200)::geometry, 102039) as shape, latitude, longitude, id, shape_area
  into grid_5deg
  from grid_5deg_nhf_coverage;

In order to restore these tables into a table, the following prequisites must be met:
* The postGIS extension must be installed.
* Custom SRID 102039 must be defined in the spatial_ref_sys table. Note that you might need to authorize the database owner to be able to do so.

create extension postgis;

-- If the following insert fails, try running this.
--alter table spatial_ref_sys owner to dbowner;

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 102039, 'ESRI', 102039, '+proj=aea +datum=NAD83 +x_0=0.0 +y_0=0.0 +lon_0=96dW +lat_0=23dN +lat_1=29d30''N +lat_2=45d30''N +towgs84=-0.9956000824677655,1.901299877314078,0.5215002840524426,0.02591500053005733,0.009425998542707753,0.01159900118427752,-0.00062000005129903 +no_defs <>', 'PROJCS["USA_Contiguous_Albers_Equal_Area_Conic_USGS_version",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Albers"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-96.0],PARAMETER["Standard_Parallel_1",29.5],PARAMETER["Standard_Parallel_2",45.5],PARAMETER["Latitude_Of_Origin",23.0],UNIT["Meter",1.0],AUTHORITY["ESRI","102039"]]');


The database dump is a custom-format archive file, and can be restored to a database using the following command:

pg_restore -U postgres -d databasename nested_hexagon_framework.pgdump.bak > load-nested_hexagon_framework.txt 2>&1

The database dump was created by running:

pg_dump -d nsx -h localhost -U nsxadmin -F c -t nhf_hexes -t nhf_cogs -t nhf_wheels -t nhf_wheels_smoothed -t nhf_summary_hexes_l1 -t nhf_summary_hexes_l2 -t nhf_summary_hexes_l3 -t grid_5deg -t grid_5deg_nhf_coverage -f nested_hexagon_framework.pgdump.bak