# README.us_usgs

The files in this section result from the conversion of datasets originating
from USGS

TODO: Aren't they coming from NOAA instead ?

## Included grids

### USA: NAD27 -> NAD83

*Source*: USGS  
*Format*: GeoTIFF converted from CTable2  
*License*: Public Domain

* alaska.tif - Alaska
* conus.tif - Conterminous U.S.
* hawaii.tif - Hawaii
* prvi.tif - Puerto Rico, Virgin Is.
* stgeorge.tif - St. George Is, Alaska
* stlrnc.tif - St. Lawrence Is., Alaska
* stpaul.tif - St. Paul Is., Alaska

### USA: NAD83 -> NAD83 (HARN/HPGN)

*Source*: USGS
*Format*: GeoTIFF converted from CTable2
*License*: Public Domain

Grid data for high precision conversion of geographic coordinates from
the original NAD83 (1986) (EPSG:4269) to NAD83 High Precision Geodetic Networks
(HPGNs) (EPSG:4152), also referred to as High Accuracy Reference Networks (HARNs).
NAD 83 coordinates based on the HPGN/HARN surveys changed approximately 0.2
to 1.0 meter relative to the original NAD 83 (1986) adjustment.

* FL.tif - Florida
* MD.tif - Maryland
* TN.tif - Tennessee
* WI.tif - Wisconsin
* WO.tif - Washington, Oregon, N. California