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how can I convert OGC WKT to Proj4 string

http://spatialreference.org/ref/epsg/3052/

PROJCS["Reykjavik 1900 / Lambert 1900",GEOGCS["Reykjavik 1900",DATUM["Reykjavik_1900",SPHEROID["Danish 1876",6377019.27,300,AUTHORITY["EPSG","7051"]],TOWGS84[-28,199,5,0,0,0,0],AUTHORITY["EPSG","6657"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4657"],AXIS["Latitude",NORTH],AXIS["Longitude",EAST]],UNIT["metre",1,AUTHORITY["EPSG","9001"]]]

  • Depending on PROJ.4 version you might be able to use "+axis wnu" but I'm not sure if that's at the command line level or in the library. – mkennedy Mar 14 '16 at 18:33
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GDAL knows the Reykjavik 1900 GCS, with this parameter string:

+proj=longlat +a=6377019.27 +b=6355762.5391 +towgs84=-28,199,5,0,0,0,0 +no_defs

There are no parameters given for the Lambert projection. That might be a reason why EPSG:3052 is not implemented in Proj.4/GDAL.

The EPSG registry notes:

Latitude of natural origin  65° N
Longitude of natural origin 19° 1' 19.65" W

but no information on the projection method. It might be different from lcc and laea which are available in Proj.4/GDAL.

http://www.raunvis.hi.is/~geirf/seg/seg-ind.htm gives some hints:

"maps based on "Reykjavík 1900" datum drawn in Lambert Conformal Conic projection with one standard parallel (65° N) and the center point (x,y)=(0,0) at (65°N, 19.022°W), x pointing West at that point and y North."

So you can try these parameters:

+proj=lcc +a=6377019.27 +b=6355762.5391  +lat_1=65 +lat_0=65 +lon_0=-19.022 +x_0=0 +y_0=0 +axis=wnu +towgs84=-28,199,5,0,0,0,0 +units=m +no_defs

to get this coordinate grid, displayed on a Web Mercator background:

enter image description here

There is an online calculator at http://cocodati.lmi.is/cocodati/cocodat-i.jsp that can transform from and to Lambert 1900. It uses a 7-parameter datum transformation, which might be better than the 3-parms that GDAL uses. The offline manual from http://cocodati.lmi.is/cocodati/cocodati-manual.pdf gives some background on this, but has a typo on the dx parameter.

So lets test with cs2cs:

cs2cs +proj=lcc +a=6377019.27 +b=6355762.5391  +lat_1=65 +lat_0=65 +lon_0=-19.022 +x_0=0 +y_0=0 +axis=wnu +towgs84=-28,199,5,0,0,0,0 +units=m +no_defs +to +init=epsg:4326 -f "%%.8f" <Island-Lambert.txt >Island-wgs84.txt
cs2cs +proj=lcc +a=6377019.27 +b=6355762.5391  +lat_1=65 +lat_0=65 +lon_0=-19.022 +x_0=0 +y_0=0 +axis=wnu +towgs84=556.020,-168.701,942.364,4.154,-0.269,-2.279,-3.729 +units=m +no_defs +to +init=epsg:4326 -f "%%.8f" <Island-Lambert.txt >>Island-wgs84.txt
cs2cs +proj=lcc +a=6377019.27 +b=6355762.5391  +lat_1=65 +lat_0=65 +lon_0=-19.022 +x_0=0 +y_0=0 +axis=wnu +towgs84=556.020,-168.701,942.364,-4.154,0.269,2.279,-3.729 +units=m +no_defs +to +init=epsg:4326 -f "%%.8f" <Island-Lambert.txt >>Island-wgs84.txt

on a test point at 150000 -100000 which delivers:

-22.09304048    64.07190553 -1053.88158670
-22.09839453    64.06973810 62.39101574
-22.09264623    64.07046456 62.60636384

The online converter computes 64.070464568(N) 22.092771204(W) so the last parameter set fits best:

+proj=lcc +a=6377019.27 +b=6355762.5391  +lat_1=65 +lat_0=65 +lon_0=-19.022 +x_0=0 +y_0=0 +axis=wnu +towgs84=556.020,-168.701,942.364,-4.154,0.269,2.279,-3.729 +units=m +no_defs

The offset is about 5 meters to the East. You might have to consider tectonic moves if you need high accuracy.

  • The projection method is detailed in guidance note 7-2 - PDF as well as in the metadata of the operation method:9826. Same as LCC (1 std parallel) but coordinates are west (positive west), north rather than east, north. – mkennedy Mar 14 '16 at 18:27
  • Thanks mkennedy for the guidance note 7-2 - PDF No link to add comment to Andrej answer :) Thank you for your help Andrej this help me a lot – Sigster Mar 15 '16 at 20:45
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It seems that it is not possible. It should be an easy task for gdalsrsinfo http://www.gdal.org/gdalsrsinfo.html but when I saved the OGC WKT into a text file I got just an empty result.

gdalsrsinfo ogc_wkt.txt -o proj4

PROJ.4 : ''

Propably Proj.4 does not implement some parts of that coordinate system.

  • if it was easy then spatialreferencing.org would have done it :-) – Ian Turton Mar 14 '16 at 13:38
  • Thanks for trying , WKT in Autocad and spatialreference.org are not the same will check this out – Sigster Mar 14 '16 at 14:04

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