[GRASS-user] GADM & Polygon files in general

[Thomas, Timothy (IFPRI)]

Thank you for your quick reply!

It leads naturally into a few questions.

1) Do you think whoever has version 1 in GRASS format would be willing
to share?

2)  Since I have over 1,000 hours of computer time in converting using
GRASS 6.4 on Linux with 8GB RAM, what in the world happened in GRASS 7
that it can now do it in only 4 hours???

3)  Would someone be able to tell me whether the commands I have been
using are the most efficient and correct, or whether that was the cause
of the slow speed in the first place?

For importing a shapefile, I used a command like:

    v.in.ogr dsn=gadm1 layer=usa_gadm1 out=usa_gadm1 -o

And if they do not have great boundaries, a command like

    v.in.ogr dsn=gadm1 layer=usa_gadm1 out=usa_gadm1 snap=0.00002 -o

To combine 2 countries, I would use something like

    v.patch -e in=usa_gadm1,can_gadm1 out=namer_gadm1

And to repair the boundaries, something like

    v.clean namer_gadm1 out=namer_cln_gadm1 tool=snap,break,rmdupl
thresh=0.00002

Thanks again for your help!

   Tim

***************************************************************
Timothy S. Thomas, Research Fellow, IFPRI
t.s.thomas at cgiar.org       +1-202-862-4605     skype: timothy.s.thomas
Rm 5035


-----Original Message-----
From: Markus Metz [mailto:markus.metz.giswork at googlemail.com] 
Sent: Monday, August 09, 2010 10:11 AM
To: Thomas, Timothy (IFPRI)
Cc: grass-user at lists.osgeo.org; Nelson, Gerald (IFPRI)
Subject: Re: [GRASS-user] GADM & Polygon files in general

Thomas, Timothy (IFPRI) wrote:
>
> Does anybody already have GADM in GRASS format?

Yes, version 1.

> Second, is there any way to
> import polygon files more efficiently or effectively?

GRASS 7, Linux 64bit, >4GB RAM -> less than 4 hours for complete
import including cleaning, topologically clean result

Alternatively, only import the polygons of your study area with
options where or spatial or flag -r

Markus M