[Proj] Still trying to get SPCS Alaska Zone 1 working!

Anthony Dunk AnthonyD at rocketmail.com
Thu May 18 20:42:12 EDT 2006


Can anyone explain to me why the US Govt document on NAD83 State Plane
Coordinate System (see link below) says that the origin for Alaska Zone
1 is lat=57N lon=133'40W or Easting=5,000,000, Northing=-5,000,000, but
when I run the Corpscon program with the appropriate setup it projects
this lat/lon to Easting=818676.713, Northing=575097.689 ? I also found
that MapInfo projects it to exactly the same Easting/Northing as

If I use PROJ's cs2cs command (Rel 4.4.7 31 March 2003) to convert
these lat/lon coordinates using the following command:

cs2cs +proj=latlong +a=6378137.0 +rf=298.257222 +to +proj=omerc
+lonc=-133.6666666667 +lat_0=57 +alpha=-36.8698976458 +k=0.9999
+x_0=5000000 +y_0=-5000000  +a=6378137 +rf=298.257222101

Then I get Easting=4999999.80 Northing=-5000000.0.

So, the PROJ command gives results which agree with the NAD83 SPCS
document, but both Corpscon and MapInfo give a consistent but different
result. What is going on, and who is correct ??!


NAD83 SPCS document:

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