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Dear Tom:
2 parts to your question:
There's the .tif containing the raster, and there's the associated .tfw
containing the georeferencing information.
Geotiffs are typically compressed tiff files. Idrisi prior to I32 (and I
believe the 4th patch to I32 is required) did not read compressed tiffs. If
you can open the .tif in Photoshop or another package and save as an
uncompressed tiff or .bmp and get it into Idrisi that way. The raster data
itself should retain its spatial integrity but you may need to look into the
possible transformation of pixel values to make sure you get the numerical
values you expect if it's quantitative data. If it's a 256-color geotiff,
you should try to keep it as a 256-color (8-bit) image thru the
transformation.
The .tfw file is a small straightforward ascii text file containing, I
believe, something like 5 lines with the upper left x and y coordinates,
the pixel spacing in x, the pixel spacing in y, and, perhaps the rotation.
You should be able to do a web search and find the format/interpretation of
the .tfw. (I have in the past.) It's just a matter of modifying your .doc
file to the parameters in the .tfw after importing the 8-bit .tif or .bmp.
Regards,
Chris Allen
-----Original Message-----
From: Tom Albright [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, August 22, 2000 11:45
To: [EMAIL PROTECTED]
Subject: Idrisi-L : reading Geotiff in old versions of Idrisi for
Windows
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Hello,
We are working with some folks overseas and want to know if they can read
GeoTIFF files with an older version of Idrisi for Windows (don't know the
version number - around the first release though (NOT IFW32)).
I'm sorry I don't have my manual here, so I can't consult it. Can someone
please guide me on whether that version of IFW could read GeoTIFFs and if
not, what freeware solutions might exist to allow them to load such images.
My understanding is the GeoTIFFs have embedded information, making it hard
to import with a generic binary importer. Is this assumption correct?
thanks,
Tom
***************************************************************
Tom Albright <[EMAIL PROTECTED]>
Senior Scientist
Raytheon
International Program - Science & Applications Branch
USGS/EROS Data Center
Sioux Falls, SD 57198
tel: (605)594-6061 fax: (605)594-6529
http://edcintl.cr.usgs.gov/ip
***************************************************************
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