[gdal-dev] Problem with file source projection doing a vertical datum reprojection

[Michael Smith]

I have a file with a projection shown, using REPORT_COMPD_CS=TRUE of:

 

COMPOUNDCRS["WGS 84 / UTM zone 17N + unknown",

    PROJCRS["WGS 84 / UTM zone 17N",

        BASEGEOGCRS["WGS 84",

            DATUM["World Geodetic System 1984",

                ELLIPSOID["WGS 84",6378137,298.257223563,

                    LENGTHUNIT["metre",1]]],

            PRIMEM["Greenwich",0,

                ANGLEUNIT["degree",0.0174532925199433]],

            ID["EPSG",4326]],

        CONVERSION["UTM zone 17N",

            METHOD["Transverse Mercator",

                ID["EPSG",9807]],

            PARAMETER["Latitude of natural origin",0,

                ANGLEUNIT["degree",0.0174532925199433],

                ID["EPSG",8801]],

            PARAMETER["Longitude of natural origin",-81,

                ANGLEUNIT["degree",0.0174532925199433],

                ID["EPSG",8802]],

            PARAMETER["Scale factor at natural origin",0.9996,

                SCALEUNIT["unity",1],

                ID["EPSG",8805]],

            PARAMETER["False easting",500000,

                LENGTHUNIT["metre",1],

                ID["EPSG",8806]],

            PARAMETER["False northing",0,

                LENGTHUNIT["metre",1],

                ID["EPSG",8807]]],

        CS[Cartesian,2],

            AXIS["easting",east,

                ORDER[1],

                LENGTHUNIT["metre",1]],

            AXIS["northing",north,

                ORDER[2],

                LENGTHUNIT["metre",1]],

        ID["EPSG",32617]],

    VERTCRS["unknown",

        VDATUM["unknown"],

        CS[vertical,1],

            AXIS["up",up,

                LENGTHUNIT["metre",1,

                    ID["EPSG",9001]]]]]

 

When trying to gdalwarp to EGM2008 using gdalwarp -t_srs epsg:32617+3855, vertical datum reprojection does not occur unless I overwride the source srs with -s_srs epsg:32617. Using GDAL 3.6.2 and proj 9.1.1. With proj_debug, I can see that the PROJ_TRACE: vgridshift: is not occurring unless the srs is overridden. I’m fairly sure that this has worked in the past but I can’t say exactly which version. This is an older geotiff that was written about 7 years ago. 

 

 

-- 

Michael Smith

US Army Corps / Remote Sensing GIS Center

 

 

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