From 204ed7ff3ee4462bf4c0ffa327683bcaabe13eff Mon Sep 17 00:00:00 2001 From: Even Rouault Date: Mon, 16 Dec 2019 20:27:09 +0100 Subject: Add README files --- us_nga/.github/README.md | 1 + us_nga/README.us_nga | 30 ++++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) create mode 120000 us_nga/.github/README.md create mode 100644 us_nga/README.us_nga (limited to 'us_nga') diff --git a/us_nga/.github/README.md b/us_nga/.github/README.md new file mode 120000 index 0000000..a728266 --- /dev/null +++ b/us_nga/.github/README.md @@ -0,0 +1 @@ +../README.us_nga \ No newline at end of file diff --git a/us_nga/README.us_nga b/us_nga/README.us_nga new file mode 100644 index 0000000..5050916 --- /dev/null +++ b/us_nga/README.us_nga @@ -0,0 +1,30 @@ +# README.us_nga + +The files in this section result from the conversion of datasets originating +from [US NGA](http://earth-info.nga.mil) + +## Included grids + +### Worldwide: EGM96 geoid model + +*Source*: [NGA](http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html) +*Format*: GeoTIFF converted from GTX +*License*: Public Domain + +15 minute worldwide geoid undulation grid that transforms physical heights to WGS84 ellipsoidal heights. + +* egm96_15.tif + +### Vertical grid: EGM2008 geoid model + +*Source*: [NGA](http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/egm08_wgs84.html) +*Format*: GeoTIFF converted from GTX +*License*: Public Domain + +2.5 minute worldwide geoid undulation grid that transforms physical heights to WGS84 ellipsoidal heights. + +This file has been produced by [GeographicLib](https://geographiclib.sourceforge.io/html/gravity.html) +using the EGM2008 gravity model and can be regenerated with the +[build_egm08_25_gtx.sh](https://raw.githubusercontent.com/OSGeo/proj-datumgrid/master/world/build_egm08_25_gtx.sh) script. + +* egm08_25.tif -- cgit v1.2.3