Speeding up load time for huge SHP files

[Ed McNierney]

Jan -

I would use PostGIS, just as Sebastian suggests!  ArcGIS does offer the
same sort of functionality, but it does take a while for me and I don't
find it easy to automate for multiple files.

	- Ed

Ed McNierney
Chief Mapmaker
Demand Media / TopoZone.com
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: 978-251-4242, Fax: 978-251-1396
ed at topozone.com



-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Sebastian Walter
Sent: Monday, August 20, 2007 7:51 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] Speeding up load time for huge SHP
files

Hi,

Jan Hartmann wrote:
>
> How would you produce that simplified version is none is available
> already?

A very conveniant way of simplifying big shapefiles is dumping them in
PostGis/Postgresql using shape2pgsql, then creating a new geometry
column and fill the data with "UPDATE <table> SET <newcolumn> =
simplify(the_geom,0.01)
where the 0.01 is the tolerance factor, this number works well for me in
longlat units. Then you can dump the table back to a shapefile using
pgsql2shp.

This way, simplifying huge shapefiles is really fast and stable, while
in ArcGIS it's taking hours, and then just crashes.

Regards,
Sebastian