| Re: Adding a GEOTIFF header to a (large) TIF file [message #47595] |
Tue, 21 February 2006 22:26 |
raval.chintan
Messages: 54
Registered: May 2005
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Member |
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cminton@gmail.com wrote:
> Hello -- Long time reader, first time poster.
>
> I am having a problem that I can't seem to crack in IDL, hopefully
> someone can help.
>
> I have a (non-geo) TIFF to which I'd like to add georeferencing
> information. I can create the GEOTIFF structure, all ready for passing
> to WRITE_TIFF, but...
>
> My problem is that the TIFF file is too large for me to read/load into
> memory, so I can't use the WRITE_TIFF function (because I can't obtain
> the "Image" parameter in the IDL workspace.)
>
> I'm at a loss, and would appreciate any suggestions/ideas,
>
> --Carl Minton
Hi Carl,
Writing the result to disk is a bit tricky The simplest option would
be to dump the TIFF to generic binary and read it using the ASSOC()
function . Then you can treat it as a simple generic binary image
(without headers or anything) and use it in program to convert it to
TIFF again.
While writing Tiff file with ASSOC function you can give the Geotiff
Option.
Hope this helps,
Chintan
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| Re: Adding a GEOTIFF header to a (large) TIF file [message #47596 is a reply to message #47595] |
Tue, 21 February 2006 20:35  |
Jeff N.
Messages: 120
Registered: April 2005
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Senior Member |
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The last time I used geo-tiff's (several years ago), the georeferencing
for a tiff file was stored in what was called a "world file." A world
file is a plain text file that accompanies a regular tif image, and it
had the extension *.tfw . So, if you had a tiff file named
satellite_image.tif, there would be an accompanying file named
satellite_image.tfw. Since you said you already have the tiff file,
and since the world file is just a plain text file, I'd look up on the
web what the format for the world file is, and just write that out like
you would any other text file. *Unless* they've changed the file
formats for geo-tiffs :)
Hope that helps,
Jeff
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