[Proj] GK31_Tirol (Austria)

[Jens Schwarz]

Hello,

I have to deal with data from Austria which is in GK31_Tirol.
We preprocess our data with ESRI and use postgis (and so proj4)
for our web applications.

Our web application must convert GK31_Tirol to WGS84 for
GPS tracks and kml exports.

We transformed some coordinates succesfully with ESRI's ArcMap.
But proj and cs2cs give me different coordinates.
The coordinates ESRI produces match e.g. Google:
http://maps.google.de/maps?f=q&hl=de&q=47.487218+12.254853&layer=&ie=UTF8&z=16&ll=47.486948,12.254992&spn=0.009295,0.013003&om=1
(street crossing)

The point was digitized with projection GK31_Tirol
and then converted with ESRI.
(GCS Transformation using MGI_To_WGS_1984_3 which lists exactly the same
parameters as the towgs84 parameters used below.)

I'm interested in the transformation GK31_Tirol to WGS84 in postgis.
I always got a significant shift with proj4 (see below).

Thanks for your help.

cheers
Jens Schwarz

######################################################

ESRI:

PROJCS["GK31_Tirol",
    GEOGCS["GCS_MGI",
        DATUM["Militar_Geographische_Institute",
            SPHEROID["Bessel_1841",6377397.155,299.1528128]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",0.0],
    PARAMETER["False_Northing",-5000000.0],
    PARAMETER["Central_Meridian",13.33333333333333],
    PARAMETER["Scale_Factor",1.0],
    PARAMETER["Latitude_Of_Origin",0.0],
    UNIT["Meter",1.0]]

MGI_To_WGS_1984_3=577.326,90.129,463.919,5.1366,1.4742,5.2970,2.4232

Tranformation with ESRI:
47.487218 12.254853
-->
-81220.587815 261502.093597

######################################################

proj4:

proj +proj=tmerc +towgs84=577.326,90.129,463.919,-5.1366,-1.4742,-5.2970,-0.4126774513 +lat_0=0 +lon_0=13.33333333333333 +k=1.000000 +x_0=0 +y_0=-5000000 +ellps=bessel +units=m +no_defs -r &lt;<EOF
> 47.487218 12.254853
> EOF
-81265.99       261441.61

cs2cs:

cs2cs +proj=latlong +datum=WGS84 +to +proj=tmerc +ellps=bessel +lat_0=0 +lon_0=13.333333 +k=1.000000 +x_0=0 +y_0=-5000000 +towgs=577.326,90.129,463.919,5.1366,1.4742,5.2970,2.4232 -r &lt;<EOF
> 47.487218 12.254853
> EOF
-81266.89       261375.36 703.77