[gdal-dev] Corner Coordinates for GeoTIFF/GeoPDF

[Greg Troxel]

You didn't say, but presumably the geopdf is in some projected
coordinate system, and you are working in a projected coordinate system
also.   Or perhaps the geopdf is projected but not really aligned to a
particular CRS.  All things to understand.

Pixels have area, and you can talk about the coordinates of the upper
left corner of the pixel, or the coordinates of the center.  You might
consider if the same corner/center is in use.  Also compute distance
between the coordinates obtained from different methods to understand if
you are talking a small fraction of a pixel, about half a pixel, about a
pixel, or many pixels.   I don't have any basis for guessing there are
any issues, but I think your discrepency may have more information in it
than you've extracted so far.