[gdal-dev] Transformation of a vertical datum

[Even Rouault]

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/
> 
> 
> 
> 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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