gshhs_dp(1)

1GSHHS_DP(1)                  Generic Mapping Tools                 GSHHS_DP(1)
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NAME

6       gshhs_dp - Line reduction using the Douglas-Peucker algorithm
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SYNOPSIS

9       gshhs_dp input.b tolerance output.b [-v]
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DESCRIPTION

12       gshhs_dp  reads  the  binary coastline (GSHHS) or political boundary or
13       river (WDBII) files and and reduces  the  complexity  of  the  line  by
14       applying the Douglas-Peucker algorithm.  It automatically handles byte-
15       swabbing between different architectures.
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17       input.b
18              GSHHS or WDBII binary data file as distributed  with  the  GSHHS
19              data supplement.  Any of the 5 standard resolutions (full, high,
20              intermediate, low, crude) can be used.
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22       tolerance
23              tolerance is maximum mismatch in km.  The larger the  value  the
24              more reduction will take place.
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26       output.b
27              The reducted data set.
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OPTIONS

30       -v     Reports progress and statistics while running.
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EXAMPLES

33       To  simplify  the  full GSHHS data set with a custom tolerance of 2 km,
34       try
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36       gshhs_dp gshhs_f.b 2 gshhs_2km.b
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REFERENCES

39       Douglas, D. H., and T. K. Peucker, Algorithms for the reduction of  the
40       number  of points required to represent a digitized line of its carica‐
41       ture, Can. Cartogr., 10, 112-122, 1973.
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AUTHOR

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