R help - Apr 2008 - Reading an ArcGIS raster file

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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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
>
> ______________________________________________
> R-help at r-project.org 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.
>

> 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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