OGR/EPSG problem with California State Plane?

Ben Discoe 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
incorrect results.

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

That is:
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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