GRASS GIS manual: v.in.gshhs

Note: This document is for an older version of GRASS GIS that is outdated. You should upgrade, and read the current addon manual page.

NAME

v.in.gshhs - Imports Global Self-consistent Hierarchical High-resolution Shoreline (GSHHS) vector data.

KEYWORDS

SYNOPSIS

v.in.gshhs
v.in.gshhs help
v.in.gshhs [-rt] input=string output=name [--overwrite] [--verbose] [--quiet]

Flags:

-r: Limit import to the current region
-t: Do not build topology for output vector
--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

input=string: Name of GSHHS shoreline file: gshhs_[f|h|i|l|c].b
output=name: Name for output vector map

DESCRIPTION

v.in.gshhs imports GSHHS shorelines as available on http://www.soest.hawaii.edu/wessel/gshhs/

GSHHS shorelines are in latlon but can be imported to any location with any projection apart from unreferenced XY projection. Reprojection is done on the fly during import.

Shorelines are imported as lines, not boundaries.

The categories in layer 1 refer to the type of shoreline: 1 = land, 2 = lake, 3 = island in lake, 4 = pond in island in lake. The field type is set to these descriptions. All lines of the same type have the same category. The categories in layer 2 refer to the GSHHS ID of each imported line. Each line has as category value the GSHHS ID in layer 2, that may be useful for further processing. An attribute table for layer 2 is not created.

The -r flag restricts the import to the current region, otherwise the full dataset is imported. With the -r flag, any line that falls into or overlaps with the current region is imported. Lines are not cropped.

NOTES

The GSHHS shorelines are in files named gshhs_[f|h|i|l|c].b where the letter in brackets indicates the resolution.

The 5 available resolutions are:

f: full resolution
h: high resolution
i: intermediate resolution
l: low resolution
c: coarse resolution

Recommended are the full and high resolution data.

The generated table for layer 1 allows a fast query of the shoreline type. If needed, a table for layer 2 can be added with v.db.addtable. The new table can be populated with category values from layer 2 (GSHHS line ID) with v.to.db. Shoreline type can be uploaded from layer 1 to layer 2 with v.to.db.

Lines can be converted to boundaries with v.type. Boundaries can be converted to areas with v.centroids.

To create a land mask, extract all lines with category = 1 in layer 1, convert them to boundaries, add missing centroids, convert area vector to raster. Accordingly for lakes, islands in lakes, and ponds in islands in lakes.

Import of world borders and world rivers also included in the zip archive is currently not supported but works, just ignore the attribute table. These world borders and rivers may be not very accurate.

REFERENCES

The processing and assembly of the GSHHS data is described in

Wessel, P., and W. H. F. Smith, 1996. A Global Self-consistent, Hierarchical, High-resolution Shoreline Database. J. Geophys. Res., 101(B4), 8741-8743.

AUTHORS

The gshhstograss tool was written by Simon Cox and Paul Wessel.
The original version of v.in.gshhs was written by Bob Covill based on gshhstograss.
Modifications and updates by Markus Neteler and Markus Metz.

Last changed: $Date: 2011-11-08 13:56:45 -0800 (Tue, 08 Nov 2011) $

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