TIF with 3 bands to data frame

Swagath

Mon, May 6, 2013 1:18 PM

Hi Roger,

Thanks for your reply. You are correct, its more similar to my previous 
post. Thanks to help from Barry, i was able to convert the '.grd' file. 
Since there is also a tif file available, i was trying to skip the part 
of downloading the software and use R directly to convert into a data 
frame.

Thanks,
Swagath

On 5/6/13 10:06 PM, Roger Bivand wrote:

On Mon, 6 May 2013, MacQueen, Don wrote:

I don't really know, exactly, but I'm going to guess.

The message says that:

In readGDAL("NArad_U_geog83.tif") : GeoTransform values not available

which is confirmed by running:

$ file NArad_U_geog83.tif
NArad_U_geog83.tif: TIFF image data, little-endian
$ gdalinfo NArad_U_geog83.tif
Driver: GTiff/GeoTIFF
Files: NArad_U_geog83.tif
Size is 5868, 2432
Coordinate System is `'
Metadata:
   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
   TIFFTAG_XRESOLUTION=671
   TIFFTAG_YRESOLUTION=671
Image Structure Metadata:
   INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  (    0.0,    0.0)
Lower Left  (    0.0, 2432.0)
Upper Right ( 5868.0,    0.0)
Lower Right ( 5868.0, 2432.0)
Center      ( 2934.0, 1216.0)
Band 1 Block=5868x16 Type=Byte, ColorInterp=Red
Band 2 Block=5868x16 Type=Byte, ColorInterp=Green
Band 3 Block=5868x16 Type=Byte, ColorInterp=Blue

so the file is just a Tiff image, not a GTiff file. It has no
information on its placing in space or dimensions. The table at:

http://mrdata.usgs.gov/radiometric/

actually says that it is a Tiff file, matched by Geosoft Grid files,
discussed in a thread resolved by Barry Rowlingson:

https://stat.ethz.ch/pipermail/r-sig-geo/2013-April/018157.html

apparently by the same person who is puzzled now. The resolution is
probably the same, so I'm not sure why the question is being repeated.

Roger

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

TIF with 3 bands to data frame

Thread (6 messages)