[R-sig-Geo] R Raster to ArcGIS

[Guy Serbin]

Hi list,

I'm going to borrow what I just learned from my other thread.  I'd
export your raster data as an ENVI file, which ArcGIS should be able
to read with the ENVI Reader for ArcGIS installed.

1. Go to www.ittvis.com and download the appropriate version of the
ENVI Reader for ArcGIS (1.1 for ArcGIS 8.3-9.1, 1.2 for ArcGIS 9.2).
You won't need the ENVI reader for ArcGIS 9.3 as support for this
format is in the upcoming version.
2. Get the caTools package for R and load it.
3. Export your data from R using write.ENVI
4. Read data into ArcGIS using usual means.

You could also see if one of the other packages, e.g., RPyGeo, allows
you to directly interface between R and ArcGIS for your purposes.

Best of luck,
Guy Serbin

On Tue, Jul 29, 2008 at 2:54 PM, Ashton Shortridge <ashton at msu.edu> wrote:
> Hi Matt (and list),
>
> ArcGIS still (as far as I know) doesn't work with rectangular cells. This
> isn't a problem with the AsciitoGrid function, but I think is more
> fundamentally a problem with Arc's raster data structure.
>
> The trick to getting around this may be to convert your matrix to a point
> object - with x, y, and z values - in R, where x and y correspond to the
> ground coordinates of each cell in the matrix. I think you would have to do
> this with your own code, but if you've programmed with arrays before it would
> not be difficult. Then interpolate these points to a square grid. The
> interpolation could be done in R (using gstat routines for example) or within
> a GIS (that is, write the xyz object to a text file, or perhaps straight to a
> shapefile, import it as a vector point set to a GIS, and then convert that to
> a raster.
>
> Hope this helps,
>
> Ashton
>
>
> On Tuesday 29 July 2008, Matt.Farnsworth at aphis.usda.gov wrote:
>> Dear list,
>>
>> I'm trying to bring an ASCII raster file into ArcGIS that resulted from
>> calling the R function Tsp(), which is in the "fields" library, followed
>> by the use of the function predict.surface() to generate the matrix of
>> predicted values. These functions use many of the same inputs as the
>> Krig() function in R. My problem is that the output is a symmetrical
>> matrix of dimension NxN, however, because R outputs an NxN matrix it
>> necessarily results in having a rectangular grid cell (e.g., x dimension
>> is 50 and y dimension is 30) for any input data set whose spatial extent
>> is not square.
>>
>> My question is; does anybody know how to import a rectangular grid from an
>> ASCII raster file into ArcGIS using something other than the AsciiToGrid
>> function in ArcGIS, which only allows for square grids?
>>
>> Thanks in advance for any help,
>> Matt
>>
>> *************************************************
>> Matt Farnsworth
>> Disease Ecologist
>> Spatial Epidemiology Unit
>> Centers for Epidemiology and Animal Health
>
> --
> Ashton Shortridge
> Associate Professor                     ashton at msu.edu
> Dept of Geography                       http://www.msu.edu/~ashton
> 235 Geography Building          ph (517) 432-3561
> Michigan State University               fx (517) 432-1671
>
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>



-- 
Guy Serbin, Ph.D.
Research Soil Scientist
Hydrology and Remote Sensing Lab
Bldg 007 Rm 104 BARC-West
10300 Baltimore Blvd
Beltsville, MD 20705-2350 USA
+1(301)504-5250 guy.serbin at gmail.com