Reading an ArcGIS raster file

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Reading an ArcGIS raster file

Juliane Struve
Dear members,

How can I read and plot an ArcGIS raster file into R ? The file has extension .aux and contains floating point bathymetry data. The purpose is to create a spatial model in R that uses ArcGIS map data. I have managed to read and plot various shape files into my R project, but I am stuck with this now. I am new to this list and also to R, so any help would be much appreciated.

Many thanks and best wishes,

Juliane


 
Dr. Juliane Struve
Adjunct Environmental Scientist
Mote Marine Laboratory
Center for Fisheries Enhancement
1600 Ken Thomson Parkway
Sarasota, Florida, 34236
(941)388-4441 Ext. 408


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Re: Reading an ArcGIS raster file

thegeologician
I don't know too much about R myself, but a little about ArcGIS:

As far as I know, the .aux files ArcGIS produces do not hold the actual
data, but metadata. The actual file should have some other extension
(dat, tif, hgz, img, csv... many more), but with rather small datasets
the metadata may be larger than the actual data (thanks, ESRI!).

As for import of rasterdata in R: I only know of the image() function,
which gives an image as tabulated data (which then again may be
displayed colourcoded...). I'd be interested in importing rasterfiles
(in a defined resolution and scaling) myself (like for plotting
rasterfiles on a map), but haven't found a good solution yet (in R, that
is)...

If you'd have access to ArcGIS, I'd go the other way: let R calculate
some rasterdata, import it in the GIS and do the mapping there..?

Sorry I can't help you more, I'm rather new to R myself...
Martin


Juliane Struve wrote:

> Dear members,
>
> How can I read and plot an ArcGIS raster file into R ? The file has extension .aux and contains floating point bathymetry data. The purpose is to create a spatial model in R that uses ArcGIS map data. I have managed to read and plot various shape files into my R project, but I am stuck with this now. I am new to this list and also to R, so any help would be much appreciated.
>
> Many thanks and best wishes,
>
> Juliane
>
>
>  
> Dr. Juliane Struve
> Adjunct Environmental Scientist
> Mote Marine Laboratory
> Center for Fisheries Enhancement
> 1600 Ken Thomson Parkway
> Sarasota, Florida, 34236
> (941)388-4441 Ext. 408
>
>
>       ________
>
> A Smarter Inbox http://uk.docs.yahoo.com/nowyoucan.html
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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Re: Reading an ArcGIS raster file

Liviu Andronic
Hello,

On Fri, Apr 4, 2008 at 8:09 PM, Martin Rittner <[hidden email]> wrote:
> I don't know too much about R myself, but a little about ArcGIS:

Doesn't grass [1] assure some kind of compatibility with ArcGIS, so as
to provide you with a "readable" file? This page [2] may be of
interest.

Liviu

[1] http://grass.itc.it/
[2] http://grass.itc.it/intro/general.php

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Re: Reading an ArcGIS raster file

Roger Bivand
Liviu Andronic <landronimirc <at> gmail.com> writes:

>
> Hello,
>
> On Fri, Apr 4, 2008 at 8:09 PM, Martin Rittner <kmr <at> thegeologician.net>
wrote:
> > I don't know too much about R myself, but a little about ArcGIS:

Come on, please do use a little time to search! An RSiteSearch("Arc raster")
gets you lots of hits on the R-sig-geo list, which has searchable archives.

The Spatial task view on CRAN links to the R-sig-geo list, and to the Rgeo
website - it includes a section on "reading and writing spatial data", which
provides plenty of leads. Reading Arc rasters is most readily done using GDAL
drivers in the rgdal package, and once the raster has been accessed, it can
be analysed at will, including rasters that are too big for ArcGIS to
analyse (by using tiles).

>
> Doesn't grass [1] assure some kind of compatibility with ArcGIS, so as
> to provide you with a "readable" file? This page [2] may be of
> interest.

Grass 6 is interfaced with R using the spgrass6 package.

Roger

>
> Liviu
>
> [1] http://grass.itc.it/
> [2] http://grass.itc.it/intro/general.php
>
> ______________________________________________
>

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Roger Bivand
Department of Economics
NHH Norwegian School of Economics
Helleveien 30
N-5045 Bergen, Norway
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Re: Reading an ArcGIS raster file

Jens Oldeland
In reply to this post by Juliane Struve
 > How can I read and plot an ArcGIS raster file into R ?

Hi Juliane,

I think what you are looking for is something like a function in the
"adehabitat" package called "import.asc". First you need to convert your
raster images in ArcGIS to ascii files. You have to use the conversion
toolbox --> from raster to --> raster to ascii in ArcGIS.

see also:
http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Raster_to_ASCII_(Conversion)

afterwards apply the image.asc function.

this might help you out:
http://finzi.psych.upenn.edu/R/library/adehabitat/html/import.asc.html

this allows to import your raster files and use it for calculations.
are you sure about your floating point data? or are there only "some"
digits after the "." ?

hope this helped?

best,
Jens


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