Hello,
We've found a regression between GeoTools 2.6.3 as compared with 2.7.5 and 8.2
with regard to datum equality.
In GeoTools 2.6.3 (the version used for prj2epsg.org) we can successfully
resolve the following WKT provided with an ESRI sourced shapefile as EPSG:3071:
PROJCS["NAD_1983_HARN_Transverse_Mercator",
GEOGCS["GCS_North_American_1983_HARN",
DATUM["D_North_American_1983_HARN",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",520000.0],
PARAMETER["False_Northing",-4480000.0],
PARAMETER["Central_Meridian",-90.0],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
In GeoTools 2.7.5 and 8.2 the conversion of the above WKT to and EPSG code
fails and I've isolated this the the fact the datum name doesn't match the
expected EPSG datum name of "NAD83 (High Accuracy Regional Network)". The WKT
below with the datum name replaced does resolve to EPSG:3071 in GeoTools 2.75
and 8.2
PROJCS["NAD_1983_HARN_Transverse_Mercator",
GEOGCS["GCS_North_American_1983_HARN",
DATUM["NAD83 (High Accuracy Regional Network)",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",520000.0],
PARAMETER["False_Northing",-4480000.0],
PARAMETER["Central_Meridian",-90.0],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
From my investigation, it appears that datum name is important in comparisons
and I came across the GeoTools DatumAlias factory and the associated
DatumAliasesTable.txt. This factory does have an entry mapping the EPSG datum
name to the ESRI datum name, and the aliases are added to the Datum instance
but this relationship doesn't appear to be used when doing datum comparisons.
I would think that if a datum name doesn't match the datum aliases should then
be consulted. Is this current behavior intended or a regression?
Thanks,
Tom Kunicki
Center for Integrated Data Analytics
U.S. Geological Survey
8505 Research Way
Middleton, WI 53562
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