[Shapelib] Shapefile decimation

David Allen David.A1 at bigpond.com
Mon Nov 13 04:09:31 EST 2006


Mike

 

The easiest solution is probably to get your programming friend to use
Shapelib code to write a decimator - it is very easy for line features.

 

-----Original Message-----
From: shapelib-bounces at lists.maptools.org
[mailto:shapelib-bounces at lists.maptools.org] On Behalf Of
Mike.Sexton at ga.gov.au
Sent: Monday, 13 November 2006 1:07 PM
To: shapelib at lists.maptools.org
Subject: [Shapelib] Shapefile decimation

 

Hi,

 

I have another query.

 

Last time I asked about making shapefiles from ASCII X,Y files. I followed
up on the suggestion of modifying shpadd.c to read from an input file and a
friend modified the code and in virtually no time produced a very good
result

 

In fact too good.

 

The files are very large. I would like to decimate the shapefiles. I have
scanned the web looking for a program that might achieve this. I found the
program fshape and to my utter amazement got it too work. I need to play
with the parameters a bit (my first attempt was a bit severe). But since the
various shapes in the shapefiles are ships tracks, it would probably be just
as valid to accept only every 10th point (or even less). I could go back to
the original datafiles and decimate them (although they were in a myriad of
formats and I kept altering my script to pull out the bits I need). This is
not an attractive option when the 2000 odd shapefiles are in a standard
format already.

 

I was wondering if a shapefile decimator existed?

 

Otherwise I might have to go back to my friend

 

Thanks

 

 

Mike Sexton

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