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<P><FONT SIZE=2 FACE="Arial">Hi All,</FONT>
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<P><FONT SIZE=2 FACE="Arial">Have a bit of a mystery:</FONT>
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<P><FONT SIZE=2 FACE="Arial">I am translating some geotiffs to ecw. These geotiffs have their geographic information internally in the headers, as well as in a tfw file. They all translate fine, and the coordinate information in the ecw file is recognised in ESRI ArcGIS.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">One TIFF file, however, I have modified in photoshop, so it lost its geographic information in the header, but it still has its tfw file. When I translate it to ecw (using the same command as for the other files), its coordinate information is not recognised by ESRI ArcGIS. However, its internal coordinate information IS recognised by other software (gdalinfo, er viewer, global mapper, etc.). </FONT></P>
<P><FONT SIZE=2 FACE="Arial">So when translating a TIFF with worldfile, the coordinate information seems to exist internally in the ecw file, is recognised by most software, but not by ArcGIS. To make it more interesting: If I translate the same file with the freeware "ecw compressor" from ER Mapper, the resulting ecw file is correctly referenced by ArcGIS.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">In ER Viewer, the image properties are different: the one created by the compressor has a WGS84 Datum, Coordinate System "Local", Coordinate type "UTM (Eastings/Northings)" (which should be latlong). For the Gdal ECW, these properties are set to "RAW".</FONT></P>
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<P><FONT SIZE=2 FACE="Arial">The command I used:</FONT>
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<P><FONT SIZE=2 FACE="Arial">C:\install\gdal\compiling\apps>gdal_translate -of ECW C:\temp\gdal\SRTM4_tasmania_ACRES_trueColour.tif C:\temp\gdal\SRTM4_tasmania_ACRES_trueColour.ecw -co "QUALITY=6"</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Gdalinfo on the TIFF:</FONT>
<BR><FONT SIZE=2 FACE="Arial">------------------------------------------------------------</FONT>
<BR><FONT SIZE=2 FACE="Arial">Driver: GTiff/GeoTIFF</FONT>
<BR><FONT SIZE=2 FACE="Arial">Size is 6150, 5217</FONT>
<BR><FONT SIZE=2 FACE="Arial">Coordinate System is `'</FONT>
<BR><FONT SIZE=2 FACE="Arial">Origin = (143.624867,-39.368522)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Pixel Size = (0.00083333,-0.00083333)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Metadata:</FONT>
<BR><FONT SIZE=2 FACE="Arial"> TIFFTAG_SOFTWARE=Adobe Photoshop CS Windows</FONT>
<BR><FONT SIZE=2 FACE="Arial"> TIFFTAG_DATETIME=2005:06:09 16:18:41</FONT>
<BR><FONT SIZE=2 FACE="Arial"> TIFFTAG_XRESOLUTION=72</FONT>
<BR><FONT SIZE=2 FACE="Arial"> TIFFTAG_YRESOLUTION=72</FONT>
<BR><FONT SIZE=2 FACE="Arial"> TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Corner Coordinates:</FONT>
<BR><FONT SIZE=2 FACE="Arial">Upper Left ( 143.6248668, -39.3685216)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Lower Left ( 143.6248668, -43.7160216)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Upper Right ( 148.7498668, -39.3685216)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Lower Right ( 148.7498668, -43.7160216)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Center ( 146.1873668, -41.5422716)</FONT>
<BR><FONT SIZE=2 FACE="Arial">Band 1 Block=6150x1 Type=Byte, ColorInterp=Red</FONT>
<BR><FONT SIZE=2 FACE="Arial">Band 2 Block=6150x1 Type=Byte, ColorInterp=Green</FONT>
<BR><FONT SIZE=2 FACE="Arial">Band 3 Block=6150x1 Type=Byte, ColorInterp=Blue</FONT>
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<P><FONT SIZE=2 FACE="Arial">Why is the coordinate information written to the header of the ECW file different if a TFW is used? It's not a drama, but it would be nice if it worked in ESRI.</FONT></P>
<P><FONT SIZE=2 FACE="Arial">Regards,</FONT>
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<P><FONT SIZE=2 FACE="Arial">Jacob</FONT>
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