$LastChangedDate: 2017-06-14 17:11:54 -1000 (Wed, 14 Jun 2017) $ $Revision: 679 $ Note: If you are adding the gshhg-gmt-x.x.x BEFORE you install GMT then make sure to set the GSHHG_PATH setting in cmake/ConfigUser.cmake before building GMT. If you are adding gshhg-gmt-x.x.x AFTER installing GMT then you need to specify its path via gmt.conf's DIR_GSHHG setting. -------------------------------------------------------------------- Global Self-consistent Hierarchical High-resolution Geography, GSHHG Version 2.3.7 June 15, 2017 Distributed under the Lesser GNU Public License Updates the Northern Mariana Islands with CUPS data from NOAA, adds two missing islands to northern Norway, and adds in the missing Kosovo-Serbia boundary. Earlier GSHHG Version-specific comments: ==================================================================== Version 2.3.6 August 19, 2016 Fixed 11 crossings in Antarctica grounding line and one in the ice front. Added missing islands Georgetown and MacMahan, ME, and updated Jan Mayen, Norway [thanks to Norwegian Polar Institute] ==================================================================== Version 2.3.5 April 12, 2016 Added missing boundary between Sudan and South Sudan. Fixed non-closure of the Slovenia, Croatia and Hungary borders. ==================================================================== Version 2.3.4 Jan 1, 2015 Corrected formatting error in the binary versions of the borders and rivers files. Added "Lake" Maelaren (Sweden) to the coastline which reverted 11 "lakes" to their proper status as islands. Version 2.3.3 Nov 2014: Removed the obsolete Saudi-Kuwait Neutral Zone diamond-shaped border and replaced with something resembling what Google Earth shows. Version 2.3.2 August 2014: Removed several internal crossovers for the two new Antarctica polygons. All other polygons are unchanged. Version 2.3.1 July 2014: Updated to include Peter I Island near Antarctica which had gone missing during the switch to the Antarctica data source for 2.3.0. Version 2.3.0 Feb 2014: This data set consists of three related components: GSHHS: Global Self-consistent Hierarchical High-resolution Shorelines: These originate as individual polygons at five different resolutions. The ocean-land shorelines derive from WVS (World Vector Shoreline project) [Soluri and Woodson, 1990] while the polygons for lakes, islands-in-lakes, and ponds-in-islands- in-lakes derive from WDBII [Gorny, 1977], which is a much older and lower-quality data product. Our compilation combines these data into a self-consistent product; see Wessel and Smith [1996] for processing details. Over the years we have manually added new data in areas that were poorly represented in the original data set; however, as users zoom in closely they can see that the old data may in places be mis-registered relative to recent data such as used in Google Earth. AC: Starting with release 2.3.0 we have replaced the poor Antarctica polygon and associated islands with newer and more accurate data from Bohlander and Scambos (2007) via Atlas of the Cryosphere. This lets us consider two polygon: ice-line and grounding line. New processing was needed to allow a run-time switch on which polygon to use (since it changes how many islands to include). Antarctic ice-front polygons are given level 5 while Antarctic grounding-line polygons are given level 6. Non-GMT users of these data should skip one of these two levels are reset the other one to level = 1. The next GMT5 release 5.2.0 will allow users to select their Antarctica coastline while older versions will simply use the ice-front line as the single Antarctica coastline; the grounding line data are not visible to those versions. WDBII: CIA World Data Bank II lineaments for borders and rivers. Over the years, political boundaries have changed and we have updated these to reflect realities based on feedback from our users. As mentioned above, WDBII is also used for lakes. GSHHG is distributed in several representations: 1. The binary and shapefile distributions provide the complete GSHHS polygons and WDBII lineaments in their five resolutions (i.e., after our full processing), and differ only in the file formats (native binary data files versus standard GIS shapefiles). These distributions are normally used by users interested to use these data outside the standard GMT-based environment, or GMT users who wish to access the whole GSHHS polygons. 2. The netCDF distribution provides specially processed netCDF representations of GSHHS and WDBII where the polygons and lines have been subdivided and indexed to deliver rapid map- making for GMT. Users who wish to access GSHHG outside of GMT are advised to use the binary and shapefile version of the actual polygons as there is no user documentation for how to access the netCDF files. Many thanks to Tom Kratzke, Metron Inc., for patiently testing many draft versions of GSHHS and reporting inconsistencies such as erratic data points and crossings. References: Bohlander, J. and T. Scambos. 2007. Antarctic coastlines and grounding line derived from MODIS Mosaic of Antarctica (MOA), Boulder, Colorado USA: National Snow and Ice Data Center. Gorny, A. J. (1977), World Data Bank II General User GuideRep. PB 271869, 10pp, Central Intelligence Agency, Washington, DC. Soluri, E. A., and V. A. Woodson (1990), World Vector Shoreline, Int. Hydrograph. Rev., LXVII(1), 27–35. Wessel, P., and W. H. F. Smith (1996), A global, self-consistent, hierarchical, high-resolution shoreline database, J. Geophys. Res., 101(B4), 8741–8743. Earlier GSHHG Version-specific comments: ==================================================================== Version 2.2.4 Nov 2013: We added three missing lakes (Mono, Trinity, and Isabella) in California, plus two islands in Lake Mono. Also found a bug in polygon_consistency that failed to find some spikes (~20-25 polygons affected), as well as an incorrect lake in Antarctica. -------------------------------------------------------------------- ==================================================================== Version 2.2.3 July 2013: We eliminated ~120 spikes (< 2m thick excursions) from a few dozen full resolution polygons. Also fixed an old mistake in Baffin Island in all but the crude resolution; this also converted two mislabeled "lakes" into islands in the full and high resolution data. -------------------------------------------------------------------- Version 2.2.2 January 2013: We have removed Sandy Island, Coral Sea (non feature), shifted Society Island polygons ~1 arc minute to the west, and replaced Mehetia Island with better data. Furthermore, 50 islands that were imprecise duplicates of more accurate WVS features were removed. Apart from the Agalega islands, these duplicates were mostly found in the Red Sea, the Persian Gulf, and in the Cook-Austral region. GSHHG is now released under the lesser GNU License, v3 or any earlier version. -------------------------------------------------------------------- Version 2.2.1 July 2012: We have renamed the product GSHHG since it contains more than just shorelines (we distribute political boundaries and rivers as well). The GSHHG building and distribution is now fully decoupled from GMT. We have also changed the name of the netCDF files for GMT to use the more standard extension *.nc. Furthermore, the packages have been renamed for clarity and follow the form gshhg-{gmt,bin,shp}-.{tar,zip} There are no significant changes to the actual data features, other than a glitch in SA-NT border in Australia and removal of 7 zero-length border segments. Following the rebranding to GSHHG the names of the distribution files have changed as well. -------------------------------------------------------------------- Version 2.2.0 July 2011: The area of small (< 0.1 km^2) polygons got truncated to 0. This would cause gshhs to consider them as lines (borders or rivers) instead of polygons. Furthermore, the areas were recomputed using the WGS-84 ellipsoid as the previous area values were based on a spherical calculation. Thanks to José Luis García Pallero for pointing this out. We now store the area with a magnitude scale tuned to each polygon. Also, the greenwich flag is now a 2-bit flag composed of 1 (crosses Greenwich), 2 (crosses Dateline), 3 (both) or 0 (no such crossing). See gshhs.[ch] for details. Finally, the binary gshhs files now store Antarctica in -180/+180 range so as to avoid a jump when dumped to ASCII. Also, the WDBII shapefiles only had the first 3 levels of rivers; version 2.2.0 has all 11. Finally, to be able to detect the river-lake features in the WDBII binary files we set the river flag to 1 if a closed feature. -------------------------------------------------------------------- Version 2.1.1 March 2011: Relatively minor fixes to low-resolution polygons, including editing errors introduced in v 2.1, removing a few spikes from 4-5 polygons, and fixing Germany-Poland border near the Baltic Sea. -------------------------------------------------------------------- Version 2.1 July 2010: Fixes lack of river-lake flag in the binary and shapefile release. Shapefile polygons of level = 2 and with a negative area are river-lakes. Also include WDBII border and river data as shapefiles. -------------------------------------------------------------------- version 2.0 July 15, 2009: Differs from the previous version 1.x in the following ways. 1. Free from internal and external crossings and erratic spikes at all five resolutions. 2. The original Eurasiafrica polygon has been split into Eurasia (polygon # 0) and Africa (polygon # 1) along the Suez canal. 3. The original Americas polygon has now been split into North America (polygon # 2) and South America (polygon # 3) along the Panama canal. 4. Antarctica is now polygon # 4 and Australia is polygon # 5, in all the five resolutions. 5. Fixed numerous problems, including missing islands and lakes in the Amazon and Nile deltas. 6. Flagged "riverlakes" which are the fat part of major rivers so they may easily be identified by users. 7. Determined container ID for all polygons (== -1 for level 1 polygons) which is the ID of the polygon that contains a smaller polygon. 8. Determined full-resolution ancestor ID for lower res polygons, i.e., the ID of the polygon that was reduced to yield the lower- res version. 9. Ensured consistency across resolutions (i.e., a feature that is an island at full resolution should not become a lake in low!). 10. Sorted tables on level, then on the area of each feature. 11. Made sure no feature is missing in one resolution but present in the next lower resolution. 12. Store both the actual area of the lower-res polygons and the area of the full-resolution ancestor so users may exclude fea- tures that represent less that a fraction of the original full area. There was some duplication and wrong levels assigned to maritime political boundaries in the Persian Gulf that has been fixed. These changes required us to enhance the GSHHG C-structure used to read and write the data. As of version 2.0 the header structure is struct GSHHG { /* Global Self-consistent Hierarchical High-resolution Shorelines */ int id; /* Unique polygon id number, starting at 0 */ int n; /* Number of points in this polygon */ int flag; /* = level + version << 8 + greenwich << 16 + source << 24 + river << 25 */ /* flag contains 5 items, as follows: * low byte: level = flag & 255: Values: 1 land, 2 lake, 3 island_in_lake, 4 pond_in_island_in_lake * 2nd byte: version = (flag >> 8) & 255: Values: Should be 12 for GSHHG release 12 (i.e., version 2.2) * 3rd byte: greenwich = (flag >> 16) & 1: Values: Greenwich is 1 if Greenwich is crossed * 4th byte: source = (flag >> 24) & 1: Values: 0 = CIA WDBII, 1 = WVS * 4th byte: river = (flag >> 25) & 1: Values: 0 = not set, 1 = river-lake and level = 2 */ int west, east, south, north; /* min/max extent in micro-degrees */ int area; /* Area of polygon in 1/10 km^2 */ int area_full; /* Area of original full-resolution polygon in 1/10 km^2 */ int container; /* Id of container polygon that encloses this polygon (-1 if none) */ int ancestor; /* Id of ancestor polygon in the full resolution set that was the source of this polygon (-1 if none) */ }; Following each header structure is n structures of coordinates: struct GSHHG_POINT { /* Each lon, lat pair is stored in micro-degrees in 4-byte signed integer format */ int32_t x; int32_t y; }; Some useful information: A) To avoid headaches the binary files were written to be big-endian. If you use the GMT supplement gshhg it will check for endian-ness and if needed will byte swab the data automatically. If not then you will need to deal with this yourself. B) In addition to GSHHS we also distribute the files with political boundaries and river lines. These derive from the WDBII data set. C) As to the best of our knowledge, the GSHHG data are geodetic longitude, latitude locations on the WGS-84 ellipsoid. This is certainly true of the WVS data (the coastlines). Lakes, riverlakes (and river lines and political borders) came from the WDBII data set which may have been on WGS072. The difference in ellipsoid is way less then the data uncertainties. Offsets have been noted between GSHHG and modern GPS positions. D) Originally, the gshhs_dp tool was used on the full resolution data to produce the lower resolution versions. However, the Douglas-Peucker algorithm often produce polygons with self-intersections as well as create segments that intersect other polygons. These problems have been corrected in the GSHHG lower resolutions over the years. If you use gshhs_dp to generate your own lower-resolution data set you should expect these problems. E) The shapefiles release was made by formatting the GSHHG data using the extended GMT/GIS metadata understood by OGR, then using ogr2ogr to build the shapefiles. Each resolution is stored in its own subdirectory (e.g., f, h, i, l, c) and each level (1-4) appears in its own shapefile. Thus, GSHHS_h_L3.shp contains islands in lakes for the high res data. Because of GIS limitations some polygons that straddle the Dateline (including Antarctica) have been split into two parts (east and west). F) The netcdf-formatted coastlines distributed with GMT derives directly from GSHHG; however the polygons have been broken into segments within tiles. These files are not meant to be used by users other than via GMT tools (pscoast, grdlandmask, etc). Paul Wessel Primary contact: pwessel@hawaii.edu Walter H. F. Smith