[Proj] Alaska State Plane Coordinates (NAD83) - Hotine Oblique Mercator ??

[Anthony Dunk]

Has anyone successfully implemented support for the Hotine Oblique
Mercator for the Alaska SPCS Zone 1 (5001) using PROJ4 ?

If so, can you share your proj command string with me and if possible a
test point in lat/lon and SPCS ?

I have been trying to find this information on the web, but have been
finding conflicting info.

According to a document on the NOAA web
page(http://www.ngs.noaa.gov/PUBS_LIB/ManualNOSNGS5.pdf) the origin of
this projection is 133d40'0"W 57d0'0"N (or 5000000m east, -5000000m
north).

I get these coordinates agreeing when I use what I believe to be the
correct parameters:

+proj=omerc +k=0.9999 +lat_0=57.0 +alpha=-36.8698976458
+lonc=-133.66667 +ellps=WGS84 +units=m

Are these parameters correct ??

But then I have to manually subtract the false easting and false
northing. Stangely I cannot get these automatically handled by proj
using the normal +x_0=5000000 and +y_0=-5000000 parameters. Any ideas
why ? Are these options only available for some projections ?

Thanks for any help you can offer!

Cheers,
Anthony.



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