[GRASS-user] Raster and shape files miss aligned.
hamish_b at yahoo.com
Wed Nov 9 06:47:03 EST 2011
> My guess is that the projection information for one of the
> original files is incorrect. My bet is on the shapefile. You
> can test by importing a 3rd file where you know the
> projection info is good (e.g., something from USGS or an
> SRTM) and seeing which one matches and which one doesn't.
specifically check that the datum is set correctly.
a correct projection but wrong datum typically shows up as a
roughly 100m north-south misalignment, as the ellipsoid is less
or more squashed from the poles to the equator in one vs the
(here I use "datum" and "ellipsoid" interchangably, while
technically in grass a given datum implies its given ellipsoid)
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