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All:<br>
<br>
Here is an example of the problem Frank is talking about:<br>
<br>
The geotiff file is keyed as such:<br>
<br>
ProjLinearUnitsGeoKey (Short,1): Linear_Foot<br>
ProjFalseEastingGeoKey (Double,1): 400000<br>
<br>
So is the false easting 400,000 meters or 400,000 feet?<br>
<br>
Snip from the spec:<br>
ProjLinearUnitsGeoKey = 3076 /* <a
href="http://www.remotesensing.org/geotiff/spec/geotiff6.html#6.3.1.3">Section
6.3.1.3</a> codes<br>
ProjFalseEastingGeoKey = 3082 /* ProjLinearUnits */<br>
<br>
Frank Warmerdam wrote:
<blockquote cite="mid44007610.3020102@pobox.com" type="cite">Folks,
<br>
<br>
What are peoples opinions on how the units of linear quantities
<br>
like false easting and northing should be interpreted in a GeoTIFF
file?
<br>
<br>
Reviewing the specification (ie. the definition of
ProjFalseEastingGeoKey
<br>
in 2.7.2 of the specification) it seems clear that the false easting
and
<br>
northing should be in the units defined by ProjLinearGeoKey.
<br>
<br>
But listgeo's normalized parameter report, GDAL, and a variety of other
<br>
commercial software packages all seem to make the assumption that false
<br>
easting and northing are always in meters.
<br>
<br>
I have created a bug report against the specification about this topic,
though
<br>
it may just be that libgeotiff, GDAL and various other packages need to
be
<br>
fixed. I am worried if alot of packages get it wrong, and no one gets
it
<br>
right (other than OSSIM so far) that we might cause more problems by
changing
<br>
the common convention.
<br>
<br>
<a class="moz-txt-link-freetext" href="http://bugzilla.remotesensing.org/show_bug.cgi?id=1094">http://bugzilla.remotesensing.org/show_bug.cgi?id=1094</a>
<br>
<br>
Best regards,
<br>
</blockquote>
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