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Frank Warmerdam wrote:
<blockquote cite="mid45ACFF67.2000201@pobox.com" type="cite">Zoltan
Szecsei wrote:
<br>
<blockquote type="cite">Hi,
<br>
Is there an easy utility (linux commandline preferable, but windows OK)
to de-skew a geo-referenced scanned map?
<br>
Typically the TFW files look like this:
<br>
<br>
0.317469
<br>
0.001049
<br>
0.000994
<br>
-0.317666
<br>
-19902.462151
<br>
-3208549.358736
<br>
<br>
<br>
Why is the row-rotation different from the column rotation?
<br>
</blockquote>
<br>
Zoltan,
<br>
<br>
The gdalwarp utility will produce a nice "north up" image from a
rotated
<br>
or skewed tiff+world (or geotiff).
<br>
<br>
eg.
<br>
<br>
gdalwarp skewed_input.tif northup_output.tif
<br>
<br>
The FWTools suite includes the gdalwarp command.
<br>
<br>
<a class="moz-txt-link-freetext" href="http://fwtools.maptools.org/">http://fwtools.maptools.org/</a>
<br>
<br>
Best regards,
<br>
</blockquote>
Hi Frank (and All),<br>
I have version GDAL 1.2.6.0, released 2005/03/13 of gdalwarp so I
haven't downloaded from the pointer above. (I loaded gdal some time
back but have not had the time to investigate it yet, which is why I
didn't realise I had the tools already)<br>
<br>
My problem is that my images are 1-bit and the output image is 8-bit.
How can I keep it as 1-bit and which of the interpolation methods
should I use in order to have minimum"damage" to the resampled pixels?
(which represent 1:10000 scanned contours)<br>
<br>
I also need a TFW file - but I could probably create my own using
tiffinfo and a bit of parsing, so it is not a train-smash.<br>
<br>
I've been trying to find help-docs on writing 1-bit tiffs, but no luck
yet. Maybe you could provide some pointers, please?<br>
<br>
Thanks,<br>
Zoltan.<br>
Tiffinfo before & after gdalwarp is:<br>
<br>
zls@gl0:/home/gisphoto/wgs84/cdsm/con5m/r2v_2006/vectorised$
/usr/bin/tiffinfo <b>2916ba05.tif_r2v</b><br>
TIFFReadDirectory: Warning, 2916ba05.tif_r2v: unknown field with tag
33922 (0x8482) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_r2v: unknown field with tag
34735 (0x87af) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_r2v: unknown field with tag
34737 (0x87b1) encountered.<br>
TIFF Directory at offset 0x37684<br>
Subfile Type: (0 = 0x0)<br>
Image Width: 19843 Image Length: 25037<br>
Resolution: 800, 800 pixels/inch<br>
Bits/Sample: 1<br>
Compression Scheme: CCITT Group 4<br>
Photometric Interpretation: min-is-white<br>
Samples/Pixel: 1<br>
Rows/Strip: 6<br>
Planar Configuration: single image plane<br>
Make: Able Software Corp.<br>
Artist: R2V for Windows<br>
HostComputer: PC/MS WINDOWS<br>
Tag 33922:
1337.712036,4258.659180,0.000000,-29143.206259,-3209262.684856,0.000000,16680.531250,4275.675781,0.000000,-24271.341171,-3209250.944041,0.000000,16671.224609,21724.287109,0.000000,-24259.748502,-3214792.945296,0.000000,1317.020996,21703.632813,0.000000,-29128.942523,-3214804.706201,0.000000<br>
Tag 34735: 1,1,0,3,1024,0,1,1,1025,0,1,1,1026,34737,22,0<br>
Tag 34737: Able Software GeoTIFF|<br>
zls@gl0:/home/gisphoto/wgs84/cdsm/con5m/r2v_2006/vectorised$ <br>
<br>
<br>
zls@gl0:/home/gisphoto/wgs84/cdsm/con5m/r2v_2006/vectorised$
/usr/bin/tiffinfo <b>2916ba05.tif_north_up</b><br>
TIFFReadDirectory: Warning, 2916ba05.tif_nup: unknown field with tag
33550 (0x830e) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_nup: unknown field with tag
33922 (0x8482) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_nup: unknown field with tag
34735 (0x87af) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_nup: unknown field with tag
34736 (0x87b0) encountered.<br>
TIFFReadDirectory: Warning, 2916ba05.tif_nup: unknown field with tag
34737 (0x87b1) encountered.<br>
TIFF Directory at offset 0x1dd82ca2<br>
Image Width: 19915 Image Length: 25124<br>
Bits/Sample: 8<br>
Sample Format: unsigned integer<br>
Compression Scheme: None<br>
Photometric Interpretation: palette color (RGB from colormap)<br>
Samples/Pixel: 1<br>
Rows/Strip: 1<br>
Planar Configuration: single image plane<br>
Color Map: (present)<br>
Tag 33550: 0.317459,0.317459,0.000000<br>
Tag 33922:
0.000000,0.000000,0.000000,-29570.603456,-3207888.676293,0.000000<br>
Tag 34735:
1,1,0,11,1024,0,1,2,1025,0,1,1,1026,34737,22,0,2048,0,1,32767,2049,34737,8,22,2050,0,1,32767,2054,0,1,9102,2056,0,1,32767,2057,34736,1,0,2059,34736,1,1,3076,0,1,9001<br>
Tag 34736: 6378137.000000,298.257224<br>
Tag 34737: Able Software GeoTIFF|unnamed|<br>
zls@gl0:/home/gisphoto/wgs84/cdsm/con5m/r2v_2006/vectorised$ <br>
<br>
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