Thanks for the help. I am in the process of including a trend with distance to the pond. Alex -----Original Message----- From: Edzer Pebesma [mailto:edzer.pebesma at uni-muenster.de] Sent: Monday, 7 February 2011 5:23 PM To: r-sig-geo at r-project.org Subject: Re: [R-sig-Geo] Incorporating boundaries into kriging
On 02/07/2011 03:58 AM, Alex Lechner wrote:
Hi, I have a number of point measurements of soil electrical conductivity surrounding a large pond (see http://www.flickr.com/photos/32778961 at N04/5423900854/ ) which I am trying to create a kriged surface for. Is there any way of excluding distances across the pond in the variogram calculations (see http://www.flickr.com/photos/32778961 at N04/5423901056/ ).
I guess with a lot of work -- using package rgeos, check every point pair whether the line connecting them crosses the pond, then exclude these pairs from the variogram cloud and bin them. I'm not sure how much it would help you. You'd not be the first if in a next step you'd like to krige and exclude points that cross the pond -- an action that can lead to very weird interpolation surfaces, because points suddenly appear "visible" when turning around a corner. Have you tried including a trend with distance to the pond?
Thanks, Alex Lechner Research Fellow Centre for Mined Land Rehabilitation Sustainable Minerals Institute Level 5, Sir James Foots Building (47A) Cnr Staff House and College Roads University of Queensland ST LUCIA, QLD, 4072 w: +61 (0)7 3346 4021 m: +61 (0)401 233 019 f: +61 7 3346 4056 e: a.lechner at uq.edu.au [[alternative HTML version deleted]]
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Edzer Pebesma Institute for Geoinformatics (ifgi), University of M?nster Weseler Stra?e 253, 48151 M?nster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de http://www.52north.org/geostatistics e.pebesma at wwu.de