[Gdal-dev] Projection definitions for epsg:2391-2393 (Finnish KKJ)

[Rahkonen Jukka]

Hello,

For some reasons there are two versions of Finnish KKJ parameters hanging around in the projection libraries.  I checked that the situation is the same at least in MS4W and FW Tools Windows packages.  In the files "\FWTools1.2.2\proj_lib\epsg" and "\ms4w\proj\nad\epsg" the definition are like this:
<2393> +proj=tmerc +lat_0=0 +lon_0=27 +k=1.000000 +x_0=3500000 +y_0=0 +ellps=intl +units=m +no_defs  <>

In the same directories the corresponding "esri" files include also the towgs84 parameters:
<2393> +proj=tmerc +lat_0=0 +lon_0=27 +k=1.000000 +x_0=3500000 +y_0=0 +ellps=intl +towgs84=-90.7,-106.1,-119.2,4.09,0.218,-1.05,1.37 +units=m +no_defs  no_defs <>

In practice this means that if you re-project something to/from anything else than between the KKJ zones
a) Projections given as epsg:2393 and esri:2393 (or taken from esri .prj file) will lead to different result.
b) If epsg-reference is used the result is always wrong resulting to something like 100-150 metre position error.

I think that the definitions in epsg file should be corrected. Or is there some reason, historical or other, for not including the towgs84 parameters there?

Regards,

-Jukka Rahkonen-