wrong proj4text for epsg 31467

[klemensp]

In table spatial_ref_sys for srid 31674 srtext and proj4text do not match.

Proj4text has different ellipsoid than srtext definition.

Check epsg.io register.

​http://epsg.io/31467-1777

[pramsey]

In spatial_ref_sys, the definition is

+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +datum=potsdam +units=m +no_defs

The "datum" parameter embeds an implicit ellipse, whereas the epsg.io representation uses an explicit ellipse. Here's the code from proj.4 defining the "potsdam" datum

src/pj_datums.c:
"potsdam",  "towgs84=598.1,73.7,418.2,0.202,0.045,-2.455,6.7",  "bessel",  "Potsdam Rauenberg 1950 DHDN",

This looks the same as what epsg.io is using. Having an explicit datum allows proj.4 to apply datum shift grids, where they exist, so this representation is preferable.

[klemensp]

Hello!

Thanks for explanation!

Klemen