Swagath,

The raster package works great for manipulating the data into different
structures.  The raster from the link provided does not contain any
projection or extent information.  I'm not quite as familiar with RGDAL,
but perhaps that's what causes the error.  Use the code below to get the
data.frame:

library(raster)

x <- stack('NArad_U_geog83.tif')

df <- as.data.frame(x)

#-Andrew


On Mon, May 6, 2013 at 12:11 PM, MacQueen, Don <macqueen1@llnl.gov> wrote:

> I don't really know, exactly, but I'm going to guess.
>
> The warning message refers to missing "GeoTransform" values. I find that
> suggestive of information about the coordinate system. The website also
> has a link to download a "TFW", which I believe contains coordinate system
> information. This is supported by the absence of proj4string info in your
> summary info. Try downloading the TFW file, putting it in the same
> directory as the tif, and then try reading again with rgdal.
>
> Instead, you might consider reading the file using the raster package;
> conversion to a suitable data frame might be simpler from that point.
>
> -Don
>
> --
> Don MacQueen
>
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
>
>
>
>
>
> On 5/3/13 5:41 AM, "Swagath Navin" <swagathnavin82@gmail.com> wrote:
>
> >Hello all,
> >
> >I am new to rgdal. I downloaded a tif file from
> >'http://mrdata.usgs.gov/radiometric/data/NArad_U_geog83.tif' which i
> >would like to convert into a regular data frame so that i can plot it
> >using ggplot2.
> >
> >when i tried to read the file using readGDAL i get a warning message
> >
> >NArad_U_geog83.tif has GDAL driver GTiff
> >and has 2432 rows and 5868 columns
> >Warning message:
> >In readGDAL("NArad_U_geog83.tif") : GeoTransform values not available
> >
> >What does it mean?
> >
> >Here s the summary of the file:
> >
> >Object of class SpatialGridDataFrame
> >Coordinates:
> >   min  max
> >x   0 5868
> >y   0 2432
> >Is projected: NA
> >proj4string : [NA]
> >Grid attributes:
> >   cellcentre.offset cellsize cells.dim
> >x               0.5        1      5868
> >y               0.5        1      2432
> >Data attributes:
> >      band1           band2           band3
> >  Min.   :  0.0   Min.   :  0.0   Min.   :  0
> >  1st Qu.:255.0   1st Qu.:255.0   1st Qu.:255
> >  Median :255.0   Median :255.0   Median :255
> >  Mean   :222.4   Mean   :231.1   Mean   :226
> >  3rd Qu.:255.0   3rd Qu.:255.0   3rd Qu.:255
> >  Max.   :255.0   Max.   :255.0   Max.   :255
> >
> >Can anyone please tell me which packages i should look into for
> >converting it into a data frame so that i can plot it using ggplot2.
> >
> >Thanks,
> >Swagath
> >
> >_______________________________________________
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> >R-sig-Geo@r-project.org
> >https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
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-- 
*Andrew P. Vitale*
Masters Student
Department of Geography
University of Nevada, Reno
(412) 915-3632
vitale232@gmail.com

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