gshhs_dp − Line reduction using the Douglas-Peucker algorithm
gshhs_dp input.b tolerance output.b [−v]
gshhs_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 GSHHS 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.
−v |
Reports progress and statistics while running. |
To simplify the full GSHHS data set with a custom tolerance of 2 km, try
gshhs_dp gshhs_f.b 2 gshhs_2km.b
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.
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 ssubroutine forms the basis for this program.
GMT(1), gshhs(1) gshhstograss(1)