Global Self-consistent Hierarchical High-resolution Shorelin
Добавлено: 26 мар 2010, 23:43
GSHHS Global Self-consistent Hierarchical High-resolution Shorelines
version 2.0 July 15, 2009
Формат: ESRI shapefile format
Distributed under the Gnu Public License
gshhs_f Full resolution data
gshhs_h High resolution data
gshhs_i Intermediate resolution data
gshhs_l Low resolution data
gshhs_c Crude resolution data
GSHHS ("Global Self-consistent, Hierarchical, High-resolution Shoreline Database") is a high-resolution shoreline data set amalgamated from two data bases (the CIA world database WDBII, and the World Vector Shoreline database) in the public domain. The data have undergone extensive processing and are free of internal inconsistencies such as erratic points and crossing segments. The shorelines are constructed entirely from hierarchically arranged closed polygons. The four-level hierarchy is as follows: seashore, lakes, islands within lakes, ponds within islands within lakes.
The data can be used to simplify data searches and data selections, or to study the statistical characteristics of shorelines and land-masses. It comes with access software and routines to facilitate decimation based on a standard line-reduction algorithm.
As of version 2.0 the header structure is
struct GSHHS { /* 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 >> & 255: Values: Should be 7 for GSHHS release 7 (i.e., version 2.0)
* 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) */
}
Offsets have been noted between GSHHS and modern GPS positions.
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 GSHHS lower resolutions over the years. If you use gshhs_dp to
generate your own lower-resolution data set you should expect these problems.
The shapefiles release was made by formatting the GSHHS 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).
Входит в состав Geodata Repository OSGeo
LandcoverDB GSHHS Detail
GSHHS - Potential Datasources OSM
v.in.gshhs - import Global Self-consistant Hierarchical High-resolution Shoreline (GSHHS) data
(GRASS Vector Import Program)
http://www.soest.hawaii.edu/pwessel/gshhs/index.html
Геодезическая привязка изображений от геостационарных спутников по контуру диска Земли и электронным картам
Н.А. Егошкин, В.В. Еремеев, Е.П. Козлов, И.В. Москатиньев, А.Э. Москвитин
version 2.0 July 15, 2009
Формат: ESRI shapefile format
Distributed under the Gnu Public License
gshhs_f Full resolution data
gshhs_h High resolution data
gshhs_i Intermediate resolution data
gshhs_l Low resolution data
gshhs_c Crude resolution data
GSHHS ("Global Self-consistent, Hierarchical, High-resolution Shoreline Database") is a high-resolution shoreline data set amalgamated from two data bases (the CIA world database WDBII, and the World Vector Shoreline database) in the public domain. The data have undergone extensive processing and are free of internal inconsistencies such as erratic points and crossing segments. The shorelines are constructed entirely from hierarchically arranged closed polygons. The four-level hierarchy is as follows: seashore, lakes, islands within lakes, ponds within islands within lakes.
The data can be used to simplify data searches and data selections, or to study the statistical characteristics of shorelines and land-masses. It comes with access software and routines to facilitate decimation based on a standard line-reduction algorithm.
As of version 2.0 the header structure is
struct GSHHS { /* 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 >> & 255: Values: Should be 7 for GSHHS release 7 (i.e., version 2.0)
* 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) */
}
Offsets have been noted between GSHHS and modern GPS positions.
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 GSHHS lower resolutions over the years. If you use gshhs_dp to
generate your own lower-resolution data set you should expect these problems.
The shapefiles release was made by formatting the GSHHS 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).
Входит в состав Geodata Repository OSGeo
LandcoverDB GSHHS Detail
GSHHS - Potential Datasources OSM
v.in.gshhs - import Global Self-consistant Hierarchical High-resolution Shoreline (GSHHS) data
(GRASS Vector Import Program)
http://www.soest.hawaii.edu/pwessel/gshhs/index.html
Геодезическая привязка изображений от геостационарных спутников по контуру диска Земли и электронным картам
Н.А. Егошкин, В.В. Еремеев, Е.П. Козлов, И.В. Москатиньев, А.Э. Москвитин
