Friday, October 17, 2014

Spatial reference systems and transformations in Austria

Transforming data from Austrian local coordinate system to WGS84 should be a no brainer but this is GIS stuff we are talking about and therefor it isn't :)

First I am posting some great references for my own sanity that I find it again and that other GIS, Geoinformatik students find some help.

Link to epsg codes for Austria ESRI Synergis:
  • Für Datumsübergänge von MGI nach WGS 1984 sollte, falls keine genauen Werte für die 7 Parameter Transformation vorliegen, jene der ÖK 50 vom BEV verwendet werden - dies entspricht MGI_To_WGS_1984_3 (EPSG-code 1618).

Link 1: We in Austria DO have a Datum shift in order to move from a Projected Coordinate System to Geographic Coordinate system and the two magic code numbers are in this file below (1618(the rest of us in Austria and 1194(for Steirmark))

BIG NOTE on PROJ4 taken from the homepage:
       The  proj  program  is  limited  to   converting
       between  geographic  and  projection coordinates
       within one datum.

       The cs2cs program operates similarly, but allows
       translation  between any pair of definable coor‐
       dinate  systems,  including  support  for  datum
How to call this from Python using the python implementatino of Proj4 library (code taken from the source code of pyProj4 library) and simplified for your reading pleasure.

This github gist is here

Have fun playing with projections!