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<p class="MsoNormal">Hi<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am a relative newbie to GIS programming so forgive me if I use the wrong terminology or don’t state my problem in the most efficient GIS terms. Anyway, I have inherited a project written by an actual GIS person who is no longer with the
company. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The DTED data consists of 4 <span style="color:#1F497D">GDalDatasets</span> with actual DTED elevation data not reaching the boundaries of
<span style="color:#1F497D">GDalDatasets</span> – i.e., <span style="color:#1F497D">
GDalDatasets</span> are bigger than the actual DTED data. Our program reads the elevation data along a bearing line from a given point to some requested distance, at regular intervals, by repeatedly calling GDALRasterBand->RasterIO for a specified distance.
What I am seeing is that elevation values of 0 are returned for points between the end of the DTED data and the end of the tile.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is there any way I can distinguish between the situation above and an actual elevation of 0? RasterIO always returns CE_None and the returned value is never equal to noDataValue.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal">Mel<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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