Merge pull request #25 from and-marsh/pr-add-main-uk-geoid

Add uk_os_OSGM15_GB.tif geoid file for ODN height, UK

copyright_and_licenses.csv

@@ -219,6 +219,7 @@ sk_gku_JTSK03_to_JTSK.tif,Copyright 2013 - GKU Slovakia,CC-BY-4.0
 sk_gku_Slovakia_ETRS89h_to_Baltic1957.tif,Copyright 2005 - GKU Slovakia,CC-BY-4.0
 sk_gku_Slovakia_ETRS89h_to_EVRF2007.tif,Copyright 2014 - GKU Slovakia,CC-BY-4.0
 uk_os_OSGM15_Belfast.tif,Ordnance Survey UK,BSD-2-Clause
+uk_os_OSGM15_GB.tif,Ordnance Survey UK,BSD-2-Clause
 uk_os_OSGM15_Malin.tif,Ordnance Survey UK,BSD-2-Clause
 uk_os_OSTN15_NTv2_OSGBtoETRS.tif,Ordnance Survey UK,BSD-2-Clause
 uk_os_README.txt,Disclaimed,Public domain

travis/expected_main.lst

@@ -220,6 +220,7 @@ sk_gku_README.txt
 sk_gku_Slovakia_ETRS89h_to_Baltic1957.tif
 sk_gku_Slovakia_ETRS89h_to_EVRF2007.tif
 uk_os_OSGM15_Belfast.tif
+uk_os_OSGM15_GB.tif
 uk_os_OSGM15_Malin.tif
 uk_os_OSTN15_NTv2_OSGBtoETRS.tif
 uk_os_README.txt

uk_os/OSGM15_GB.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+if [ "$#" -lt 2 ]; then
+	echo "Usage: $(basename $0) source_file.txt output_file.tif"
+	exit 1
+fi
+
+SOURCE_FILE=$1
+TARGET_FILE=$2
+
+ETRS89_BRITISH_NAT_GRID='PROJCS["ETRS89 / British National Grid",
+    GEOGCS["ETRS89",
+        DATUM["European_Terrestrial_Reference_System_1989",
+            SPHEROID["GRS 1980",6378137,298.257222101,
+                AUTHORITY["EPSG","7019"]],
+            AUTHORITY["EPSG","6258"]],
+        PRIMEM["Greenwich",0,
+            AUTHORITY["EPSG","8901"]],
+        UNIT["degree",0.0174532925199433,
+            AUTHORITY["EPSG","9122"]],
+        AUTHORITY["EPSG","4258"]],
+    PROJECTION["Transverse_Mercator"],
+    PARAMETER["latitude_of_origin",49],
+    PARAMETER["central_meridian",-2],
+    PARAMETER["scale_factor",0.9996012717],
+    PARAMETER["false_easting",400000],
+    PARAMETER["false_northing",-100000],
+    UNIT["metre",1,
+        AUTHORITY["EPSG","9001"]],
+    AXIS["Easting",EAST],
+    AXIS["Northing",NORTH]]
+'
+RES_LAT=0.008983192446931791	# RES_NORTHING/(PI*GRS80_RAD/180)
+RES_LONG=0.015839681746927323	# RES_LAT/cos(MID_AREA_LAT)
+# RMSE = 0.0007570669375634179m
+# MAX_ERROR = 0.0019630308326981094m
+
+NO_DATA_VALUE="-32768"
+
+tail -n +2 ${SOURCE_FILE} | awk 'BEGIN {FS=","; OFS=" "} {print $2, $3, $6}' > osgm15_temp
+
+
+gdalwarp -r bilinear -dstnodata ${NO_DATA_VALUE} -tr ${RES_LONG} ${RES_LAT} -s_srs "${ETRS89_BRITISH_NAT_GRID}" -t_srs EPSG:4937 osgm15_temp osgm15_temp.tif
+gdal_translate -mo "AREA_OR_POINT=Point" osgm15_temp.tif ${TARGET_FILE}
+
+rm ./osgm15_temp ./osgm15_temp.tif
+
+# Add metadata with grid_tools of PROJ-data repository
+# ./grid_tools/vertoffset_grid_to_gtiff.py \
+# --description "ETRS89 (EPSG:4937) to ODN height (EPSG:5701). Converted from OSTN15_OSGM15_DataFile.txt" \
+# --type "GEOGRAPHIC_TO_VERTICAL" \
+# --copyright "Derived from work by Ordnance Survey. The 2-Clause BSD License https://opensource.org/licenses/bsd-license.php" \
+# --area-of-use "Great Britain mainland onshore" \
+# --source-crs "EPSG:4937" \
+# --target-crs "EPSG:5701" \
+# ${TARGET_FILE} uk_os_OSGM15_GB.tif

uk_os/uk_os_README.txt

@@ -29,6 +29,23 @@ The Belfast datum is used in the Northern Ireland.
 
 * uk_os_OSGM15_Belfast.tif
 
+### United Kingdom: OSGM15 height, ODN height -> ETRS89 ellipsoidal heights
+
+*Source*: [Ordnance Survey](https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/formats-for-developers.html)
+*Format*: GeoTIFF converted by `OSGM15_GB.sh`
+*License*: [The 2-Clause BSD License](https://opensource.org/licenses/bsd-license.php)
+
+Vertical transformation for Geoid model OSGM15, ODN height (EPSG:5701). Used in
+transformation from OSGM15 orthometric heights to ETRS89 ellipsoidal heights.
+The Belfast datum is used in the Great Britain mainland onshore.
+
+Since the original transformation should have applied to projected coordinates, this geoid model
+was reprojected to suit PROJ requirements in order to be able to apply it to geographic coordinates.
+Due to this fact slight inaccuracy can appear. In accordance to the Ordnance Survey developer pack
+test data max error is up to 0.02 m and RMSE is up to 0.00076 m.
+
+* uk_os_OSGM15_GB.tif
+
 ### United Kingdom: OSGB36 -> ETRS89
 
 *Source*: [Ordnance Survey](https://www.ordnancesurvey.co.uk/business-and-government/help-and-support/navigation-technology/os-net/formats-for-developers.html)