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<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>Dear All,</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>I am a GDAL
beginner, and I have a very basic question.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>(It is probably a
FAQ)</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>I have some TIF
file defined in UTM (zone 19N), NAD27.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>I can retrieve
from those tif :</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> - The ProjectionRef
(PROJCS["NAD27 / UTM zone 19N",GEOGCS["NAD27", … and
so on…)</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> - And the
6 affine transformation coefficients </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>I would like to
implement to raster projection: Converting a pixel coordinate (in the bitmap)
into a position in Lat/Lon coord system (in WGS84 for example)</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>I guess the way
to do it is:</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>1) Convert from
pixel coordinate to the geotiff file coordinate system, ie in my case UTM zone
19, in meters. (There is no problem for that, I will use the affine
coefficients)</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>2) Convert from
the geotiff file coordinate system to lat/lon system.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>(u,v)Pixel
---------1----------> UTM(x,y) meters ---------2----------> (Lat,Lon)radians</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>How to do 2) ??</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>Am I on the right
way?</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>Do you have a
sample doing this kind of projection?</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'>Note : I have
tried to create a OGRCoordinateTransformation with my file's OGRSpatialReference
and a simple lat/lon OGRSpatialReference. It does not work, even if the
transformation seems to be well created.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
lang=EN-GB style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=EN-GB style='font-size:
10.0pt;font-family:Arial'> </span></font></p>
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