[GRASS-user] Re: grass-user Digest, Vol 51, Issue 71

[Michael Barton]

Hi Bulent,

See some answers below.

Michael
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity 
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University

voice: 	480-965-6262 (SHESC), 480-727-9746 (CSDC)
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On Jul 28, 2010, at 2:04 AM, <grass-user-request at lists.osgeo.org> wrote:

> Date: Wed, 28 Jul 2010 12:04:06 +0300
> From: Bulent Arikan <bulent.arikan at gmail.com>
> Subject: [GRASS-user] patching
> To: grass-user at lists.osgeo.org
> Message-ID:
>        <AANLkTikYu76GGJ_nR2j=L8DUmPAdMJAP011kz98fYOSP at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Dear List,
> 
> I have several ASTER GDEM (originally Latlong) images that I want to
> reinterpolate from 30 to 10 m res. I also need to patch these images. I am
> not sure whether:
> 
> - I should patch them in Latlong using r.series, reproject into UTM and
> interpolate them using r.resamp.rst or

If you patch, use r.patch, not r.series. 

> 
> - reproject images individually into UTM, interpolate individually using
> r.resamp.rst and then patch them using r.series.

IMHO, your first option will be the most accurate. However, the reprojection and resampling will take a long time because you will have a very big map to work with.

Also, read the manual for r.resamp.rst carefully. IIRC, there are a couple tricks you need to remember about how to set the region resolution prior to running r.resamp.rst.

As an alternative, you can create a point file using r.to.vect, so that you get a point for the center of each original raster cell. Then you can set the region to 10m and use v.surf.rst or v.surf.bspline to interpolate a new map.


> 
> So far, I tried the second option. After cubic reprojection and
> interpolation to 10m the tiles have little borders of NULL areas when I
> display them together. They don't go away when patched.

This is because you tried to patch after reprojection. 

> 
> I will appreciate any advice
> Thanks.
> --
> B?LENT ARIKAN, PhD
> School of Human Evolution and Social Change
> Arizona State University
> Tempe - AZ
> 85287-2402