optimised gshhstograss

[Simon Cox]

I posted a notice earlier today about a program I wrote to extract
gshhs data into grass.  It works fine, but as I noted v.support and v.build
take a long time to run (~24 hours on my fast DEC Alpha on the full resolution
data for a rectangle including Australia!) and plotting can be slow for
large files.

I have found that the problem is that GRASS vector programs
scale very poorly for lines containing a large number of nodes.
I have now modified gshhstograss so that large lines are split into 5001
node chunks.
This has increased the speed of v.support by about x1000 for my test area,
and (probably more importantly as it is used more often) has increased the
speed of plotting using d.vect by about x20.

Version 2 of ghhstograss incorporating these changes is available at
ftp://ftp.ned.dem.csiro.au/pub/gshhstograss.tar.gz
I have also put a note in moon/grass/incoming about this.

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Dr Simon Cox                        __  \
CSIRO Exploration & Mining       ,~'  L_|\    Australian
39 Fairway, PO Box 437,       ;-'         \   Geodynamics
Nedlands, WA  6009  Australia (            \  Cooperative
    T:     +61 9 284 8443    +    ___     /  Research
    F:     +61 9 389 1906     L~~'   "\__/   Centre
simon at ned.dem.csiro.au                   W
http://www.ned.dem.csiro.au/AGCRC/people/CoxSimon/
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