Could someone explain how GCP's placed into a VRT file work, i was expecting a linear/bi-linear, or polynomial fit between the points for the simplest EPSG:4326 projection.
however that is not what i see, adjusting a single point, effects the projection of all corner points.
for example,
a vrt file that starts...
<VRTDataset rasterXSize="5328.0" rasterYSize="2160.0">
<GCPList Projection="EPSG:4326">
<GCP Id="1" Info="a" Pixel="0.0" Line="2160.0" X="-93.6369420815179" Y="41.9822570038769" />
<GCP Id="2" Info="b" Pixel="5328.0" Line="2160.0" X="-93.636924110907" Y="41.9822308438819" />
<GCP Id="3" Info="c" Pixel="5328.0" Line="0.0" X="-93.6369153669777" Y="41.9822348674463" />
<GCP Id="4" Info="d" Pixel="0.0" Line="0.0" X="-93.636927955436" Y="41.9822605751492" />
</GCPList>
.....
if i adjust the 0,0 point to be further east, when i look at the resulting remaped image, all corner image points have shifted, rather than just the single corner location for 0,0
what am i missing here?
many thanks
Joe
via Newton Mail
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