R help - Sep 2007 - geotiff or tiff files with world files

Hi,
 
I have a matrix of data which i can vizualize as an image - for example. I would
like to save this image as a geotiff file or at a tiff file with a world file
which holds the projection of my data (ultimately the data represent a map of
some sort). I know i can save the data as an ESRI grid, but i am not interested
in that.
 
I wonder if anybody knows about any code which will help me do that.
 
Thanks in advance,
 
Monica
_________________________________________________________________

s. It's easy!

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Monica Pisica <pisicandru <at> hotmail.com> writes:
> 
> 
> Hi,
> 
> I have a matrix of data which i can vizualize as an image - for example.
> I would like to save this image as a
> geotiff file or at a tiff file with a world file which holds the projection
> of my data (ultimately the data
> represent a map of some sort). I know i can save the data as an ESRI
> grid, but i am not interested in that.
> 
> I wonder if anybody knows about any code which will help me do that.
See the writeGDAL() function in the rgdal package, and hints on how to 
turn your matrix into a SpatialGridDataFrame object in the sp package. 
For example:

data(volcano)
str(volcano)
image(volcano)
grd <- GridTopology(c(0.5, 0.5), c(1, 1), c(87, 61))
SGDF <- SpatialGridDataFrame(grd, data=data.frame(volcano=c(volcano)))
image(SGDF, "volcano")

See the proj4string= argument to insert the projection in valid PROJ.4 
format. Then:

writeGDAL(SGDF, "volcano.tif", drivername = "GTiff", ...)

using the options= id needed, to pass through create options as on:

http://www.gdal.org/frmt_gtiff.html

For follow-ups, please consider the R-sig-geo list.

Roger
> 
> Thanks in advance,
> 
> Monica
> _________________________________________________________________
> 
> s. It's easy!
> 
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> 
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