OGR/EPSG problem with California State Plane?
ben at v...
Sat Jan 19 04:20:43 EST 2002
I've spent the past day trying to track down a problem with some GIS data
i've acquired from the City of Palo Alto. They say that the data uses
California State Plane, Zone 3, NAD83.
When i use OGRSpatialReference to operate on these coordinates, i get very
I've tracked down the problem to the set of parameters used to describe the
projection. They parameters are looked up by EPSGGetProjTRFInfo() which
consults the file "gdal/data/trf_nonpolynomial.csv", and gets the following
data from the file:
10433 California CS83 zone 3 [..] 36.3 -120.3 38.26 37.04 2000000 500000
standard parallel 1 38.4333333333
standard parallel 2 37.0666666666
center latitude 36.5
center longitude -120.5
false easting 2000000
false northing 500000
But, according to one online reference, the correct values are:
False Easting: 6561666.6666
False Northing: 1640416.6666
This second set of values (easting > 6 million), if correct, would explain
the Palo Alto data coordinates - and would mean that the "gdal/data" table
is very wrong.
Is there a canonical source of the parameters of state plane projections? I
spent some time with Google, and could not find one. Where did the CSV
tables that GDAL/OGR use come from? Could there be a revised or corrected
version in existence?
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