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<p class="MsoNormal"><span style="font-size:11.0pt">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> I’m trying to track down systematic pixel shift effects observed with warping data using geolocation arrays:
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><a href="https://trac.osgeo.org/gdal/ticket/6959">https://trac.osgeo.org/gdal/ticket/6959</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Essentially, the same data (image and location) provided as geolocation arrays is warped to a different output depending on how the arrays are laid out – WESN, WENS, EWSN, EWNS.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Gdalwarp produces least shift in warped data when the input arrays themselves are oriented WENS.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Is there a definitive definition for interpretation of lat,lon,value when geolocation arrays – i.e, are the lat/lon representative of pixel center (which I think should be the intent)?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Does GDAL by default assume that the geolocation value corresponds to the top/left of the pixel? Could this confusion result in the observed systematic shift?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Alternately, could the input arrays be reoriented to WENS using VRTs instead of rewriting large raster files?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Piyush<o:p></o:p></span></p>
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