GSHHG_DP(1)

NAME
gshhg_dp - Line reduction using the Douglas-Peucker algorithm

SYNOPSIS
gshhg_dp input.b tolerance output.b [-v]

DESCRIPTION
gshhg_dp reads the binary coastline (GSHHS) or political boundary or river (WDBII) files and and reduces the complexity of the line by applying the Douglas-Peucker algorithm. It automatically handles byte-swabbing between different architectures.

input.b
    GSHHS or WDBII binary data file as distributed with the GSHHG data supplement. Any of the 5 standard resolutions (full, high, intermediate, low, crude) can be used.

tolerance
    tolerance is maximum mismatch in km. The larger the value the more reduction will take place.

output.b
    The reducted data set.

OPTIONS

-v  Reports progress and statistics while running.

EXAMPLES

To simplify the full GSHHS data set with a custom tolerance of 2 km, try

gshhg_dp gshhs_f.b 2 gshhs_2km.b

REFERENCES
Douglas, D. H., and T. K. Peucker, Algorithms for the reduction of the number of points required to represent a digitized line of its caricature, Can. Cartogr., 10, 112-122, 1973.

AUTHOR
This implementation of the D-P algorithm has been kindly provided by Dr. Gary J. Robinson, Environmental Systems Science Centre, University of Reading, Reading, UK (gazza@mail.nerc-essc.ac.uk); his subroutine forms the basis for this program.

SEE ALSO
GMT(1), gshhg(1), gshhgtograss(1)