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<body lang=FR link=blue vlink=purple style='tab-interval:35.4pt'>
<div class=Section1>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>Hi Frank<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>I've found in the TIFF specification Rev
6.0 that the X/YResolution tags <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>don't have any default value.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>It's also written that these tags are
required for Bilevel Images, Grayscale <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>images, Palette color images as well as
for RGB images.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>I noticed that applications can display
the images<span style='mso-spacerun:yes'> </span>with no care (!) with <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>these tags but it's not written that
these tags can be absent.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>I'm just trying to find how to get a
default value for these tags (if any <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>but I don'tthink that it's a good idea
to fx one) or a way to calculate it.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
class=SpellE><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>Thank</span></font></span><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'> <span
class=SpellE>you</span><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>Gerald<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>"Frank
<span class=SpellE>Warmerdam</span>" <<span class=SpellE>fwarmerdam</span>@gmail.com>
a écrit dans le message de news: <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>931f8ea90507060759158ca8d2@mail.gmail.com...<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>On 7/5/05, Gérald CLETTE
<gerald.clette@free.fr> wrote:<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> Hi<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> I developped a new driver based on
the GDAL data model to handle a new <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> format with the gdal_warp tool. Then,
I tried to create a GTIFF <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> product but the new file didn't
contain the<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> XResolution, YResolution nor
ResolutionUnit tags. I thought that these <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> tags<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> were not optionnal in the GeoTiff
description.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>Gérald,<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>The XResolution, YResolution and
ResolutionUnit flags are not related to the GeoTIFF specification.<span
style='mso-spacerun:yes'> </span>I am not aware of these being required tags
in the core TIFF specification though it is possible.<span
style='mso-spacerun:yes'> </span>If so, could you <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>provide<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>a reference?<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> My question is : Is it a bug in the
Geotiff library ? Or how can I <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> manage<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> to<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>> product a "full" GeoTiff
product with gdal_warp ?<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>The -mo flag to gdal_translate can be
used to add dataset level metadata which is how the GDAL GeoTIFF<span
style='mso-spacerun:yes'> </span>driver handles the resolution information.<span
style='mso-spacerun:yes'> </span>Something like the following would set a
72dpi (dots per inch) screen resolution:<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>gdal_translate in.tif out.tif \<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><span style='mso-spacerun:yes'>
</span>-mo TIFFTAG_XRESOLUTION=72 \<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><span style='mso-spacerun:yes'>
</span>-mo TIFFTAG_XRESOLUTION=72 \<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><span style='mso-spacerun:yes'>
</span>-mo TIFFTAG_RESOLUTIONUNIT=2<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>See the TIFF tag list for details on
resolution unit values:<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><span style='mso-spacerun:yes'>
</span></span></font><font size=2 face="Courier New"><span style='font-size:
10.0pt;font-family:"Courier New"'><a
href="http://www.awaresystems.be/imaging/tiff/tifftags/resolutionunit.html"><span
lang=EN-GB style='mso-ansi-language:EN-GB'>http://www.awaresystems.be/imaging/tiff/tifftags/resolutionunit.html</span></a></span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>PS. Keep in mind that the x/yresolution
values have nothing<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>to do with geospatial resolution.<span
style='mso-spacerun:yes'> </span>It is screen/print display resolution.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>Best regards,<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>-- <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>---------------------------------------+--------------------------------<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>---------------------------------------+------<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>I set the clouds in motion - turn
up<span style='mso-spacerun:yes'> </span>| Frank Warmerdam, <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>warmerdam@pobox.com<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>light and sound - activate the windows |
</span></font><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'><a href="http://pobox.com/~warmerdam"><span
lang=EN-GB style='mso-ansi-language:EN-GB'>http://pobox.com/~warmerdam</span></a></span></font><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'>and watch the world go round - Rush<span
style='mso-spacerun:yes'> </span>| Geospatial Programmer for Rent <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span lang=EN-GB style='font-size:10.0pt;font-family:
"Courier New";mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
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