[gdal-dev] Transformation of a vertical datum

[OpenDEM]

Hi Even,

 

Thanks for your reply.

 

Unfortunately there are no shift grids available yet, but I contacted
CRS-EU.

They want to discuss this topic at the next EUREF meeting.

 

Best,

 

Martin

 

From: Even Rouault [mailto:even.rouault at spatialys.com] 
Sent: Donnerstag, 16. März 2017 17:22
To: gdal-dev at lists.osgeo.org
Cc: OpenDEM
Subject: Re: [gdal-dev] Transformation of a vertical datum

 

On jeudi 16 mars 2017 16:57:11 CET OpenDEM wrote:

> Hi,

> 

> 

> 

> I would like to transform the vertical datum EPSG:5730 to EPSG:5621

> 

> 

> 

> For more information about the European height reference systems have a
look

> at:  <http://www.crs-geo.eu/> http://www.crs-geo.eu/

> 

> 

> 

> I used gdaltransform, but the z value is not changing:

 

Yes, I you look at the output of gdalsrsinfo on both SRS, you'll see that
there is no explicit vertical shift grid mentionned (+geoidgrids=something
paramet in proj.4 string). Thus no vertical shift is done. So, you should
look if there are vertical shift grids betwen EVRF2005 &/ EVRF2000 and WGS84
ellipsoidal height, so that they can be used with proj.4

 

$ gdalsrsinfo EPSG:3035+5621

 

PROJ.4 : '+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000
+ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +vunits=m +no_defs '

 

OGC WKT :

COMPD_CS["ETRS89 / LAEA Europe + EVRF2007 height",

PROJCS["ETRS89 / LAEA Europe",

GEOGCS["ETRS89",

DATUM["European_Terrestrial_Reference_System_1989",

SPHEROID["GRS 1980",6378137,298.257222101,

AUTHORITY["EPSG","7019"]],

TOWGS84[0,0,0,0,0,0,0],

AUTHORITY["EPSG","6258"]],

PRIMEM["Greenwich",0,

AUTHORITY["EPSG","8901"]],

UNIT["degree",0.0174532925199433,

AUTHORITY["EPSG","9122"]],

AUTHORITY["EPSG","4258"]],

PROJECTION["Lambert_Azimuthal_Equal_Area"],

PARAMETER["latitude_of_center",52],

PARAMETER["longitude_of_center",10],

PARAMETER["false_easting",4321000],

PARAMETER["false_northing",3210000],

UNIT["metre",1,

AUTHORITY["EPSG","9001"]],

AUTHORITY["EPSG","3035"]],

VERT_CS["EVRF2007 height",

VERT_DATUM["European Vertical Reference Frame 2007",2005,

AUTHORITY["EPSG","5215"]],

UNIT["metre",1,

AUTHORITY["EPSG","9001"]],

AXIS["Up",UP],

AUTHORITY["EPSG","5621"]]]

 

On the contrary :

 

$ gdalsrsinfo EPSG:3035+5773

 

PROJ.4 : '+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000
+ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +geoidgrids=egm96_15.gtx
+vunits=m +no_defs '

 

OGC WKT :

COMPD_CS["ETRS89 / LAEA Europe + EGM96 geoid height",

PROJCS["ETRS89 / LAEA Europe",

GEOGCS["ETRS89",

DATUM["European_Terrestrial_Reference_System_1989",

SPHEROID["GRS 1980",6378137,298.257222101,

AUTHORITY["EPSG","7019"]],

TOWGS84[0,0,0,0,0,0,0],

AUTHORITY["EPSG","6258"]],

PRIMEM["Greenwich",0,

AUTHORITY["EPSG","8901"]],

UNIT["degree",0.0174532925199433,

AUTHORITY["EPSG","9122"]],

AUTHORITY["EPSG","4258"]],

PROJECTION["Lambert_Azimuthal_Equal_Area"],

PARAMETER["latitude_of_center",52],

PARAMETER["longitude_of_center",10],

PARAMETER["false_easting",4321000],

PARAMETER["false_northing",3210000],

UNIT["metre",1,

AUTHORITY["EPSG","9001"]],

AUTHORITY["EPSG","3035"]],

VERT_CS["EGM96 geoid height",

VERT_DATUM["EGM96 geoid",2005,

EXTENSION["PROJ4_GRIDS","egm96_15.gtx"],

AUTHORITY["EPSG","5171"]],

UNIT["metre",1,

AUTHORITY["EPSG","9001"]],

AXIS["Up",UP],

AUTHORITY["EPSG","5773"]]]

 

Even

 

 

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Spatialys - Geospatial professional services

http://www.spatialys.com

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