[Proj] Problems with EOV for Hungary (1972 Egyseges Orszagos Vetuleti)

[Roger Oberholtzer]

I am trying to use proj (C API) to project WGS84 lat/longs in EOV for
Hungary (1972 Egyseges Orszagos Vetuleti). I am trying to match some
user data. The are using ArcGis with the following definition:

        PROJCS["HD_1972_Egyseges_Orszagos_Vetuleti",
        GEOGCS["GCS_Hungarian_1972",
        DATUM["D_Hungarian_1972",
        SPHEROID["GRS_1967",6378160,298.247167427]],
        PRIMEM["Greenwich",0],
        UNIT["Degree",0.0174532925199432955]],
        PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],
        PARAMETER["False_Easting",650000],
        PARAMETER["False_Northing",200000],
        PARAMETER["Scale_Factor",0.99993],
        PARAMETER["Azimuth",90],
        PARAMETER["Longitude_Of_Center",19.048571778],
        PARAMETER["Latitude_Of_Center",47.14439372222],
        UNIT["Meter",1]]

I have set this up as:

   from = pj_init_plus(
                "+proj=latlong "
                "+ellps=WGS84");

   to = pj_init_plus(
                "+proj=somerc "
                "+lat_0=47.14439372222222 "
                "+lon_0=19.04857177777778 "
                "+k=0.99993 "
                "+x_0=650000 "
                "+y_0=200000 "
                "+ellps=GRS67 "
                "+units=m "
                "+no_defs");

     pj_transform(to, from, 1, 0, &le, &ln, &la);

When I run some test data, I am always 80 some meters away. For example:

   Ref:    Latitude:   47.7656110000 Longitude:   18.9532900000
   Ref:    Easting:       642942.000 Northing:       269097.700
   Calc:   Easting:       642857.473 Northing:       269067.872

   89.636 meters from Ref

The two Ref. lines are the user data. The Calc. line is what I get with
the pj_init_plus.

I have tried other mercator proj= statements, but it seems to make no
difference. Does "Hotine_Oblique_Mercator_Azimuth_Center" have a
counterpart in proj?

Perhaps the GRS67 definition they use is not the same as proj's default?

The user claims that the WGS84 definition they use is:

        GEOGCS["GCS_WGS_1984",
        DATUM["D_WGS_1984",
        SPHEROID["WGS_1984",6378137,298.257223563]],
        PRIMEM["Greenwich",0],
        UNIT["Degree",0.017453292519943295]]

Isn't this the standard definition?

-- 
Roger Oberholtzer

OPQ Systems / Ramböll RST

Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden

Office: Int +46 8-615 60 20
Mobile: Int +46 70-815 1696