Opened 22 months ago

Closed 22 months ago

Last modified 22 months ago

#3487 closed defect (invalid)

wrong proj4text for epsg 31467

Reported by: klemensp Owned by: pramsey
Priority: critical Milestone: PostGIS 2.2.2
Component: postgis Version: 2.2.x
Keywords: proj4text Cc: spruk.klemen@…

Description

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

Change History (2)

comment:1 Changed 22 months ago by pramsey

Resolution: invalid
Status: newclosed

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.

comment:2 Changed 22 months ago by klemensp

Hello!

Thanks for explanation!

Klemen

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