From 204ed7ff3ee4462bf4c0ffa327683bcaabe13eff Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Mon, 16 Dec 2019 20:27:09 +0100
Subject: Add README files

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 us_usgs/.github/README.md |  1 +
 us_usgs/README.us_usgs    | 41 +++++++++++++++++++++++++++++++++++++++++
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 create mode 120000 us_usgs/.github/README.md
 create mode 100644 us_usgs/README.us_usgs

(limited to 'us_usgs')

diff --git a/us_usgs/.github/README.md b/us_usgs/.github/README.md
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+../README.us_usgs
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diff --git a/us_usgs/README.us_usgs b/us_usgs/README.us_usgs
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+# 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
+
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