Sorry Even,
I should have done more research on my end up front before sending this. A
client told us his WKT 2.0 BAG was created with GDAL. Looking at it some more,
it was the vertical CRS that was WKT 2.0.
Their vertical CRS looked as follows:
<gco:CharacterString>VERTCRS["ellipse",VDATUM["NAD83(2011) / UTM zone 10N +
ellipse"],CS[vertical,1],AXIS["ellipsoid height
(h)",up,LENGTHUNIT["metre",1]]]</gco:CharacterString>
Cheers,
André
From: Even Rouault <even.roua...@spatialys.com>
Sent: April 22, 2022 13:22
To: Vautour, André (INT) <andre.vaut...@teledyne.com>; gdal-dev@lists.osgeo.org
Subject: Re: [gdal-dev] BAG CRS
External Email
André,
I don't confirm this trying:
$ gdal_translate autotest/gcore/data/byte.tif byte.bag
$ gdalinfo byte.bag -mdd xml:BAG | grep PROJCS
<gco:CharacterString>PROJCS["NAD27 / UTM zone
11N",GEOGCS["NAD27",DATUM["North_American_Datum_1927",SPHEROID["Clarke
1866",6378206.4,294.978698213898,AUTHORITY["EPSG","7008"]],AUTHORITY["EPSG","6267"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4267"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-117],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","26711"]]</gco:CharacterString>
This is WKT1
I'm wondering if the confusion might come from looking at the CRS reported by
gdalinfo, which will always be WKT2 in recent GDAL versions whatever the
encoding in the source dataset itself ?
Or perhaps you try to write a Geographic 3D CRS ? in which case WKT2 will be
used since there's no WKT1 representation for this
$ gdalwarp -overwrite autotest/gcore/data/byte.tif byte.bag -t_srs EPSG:4979
-ot float32
$ gdalinfo byte.bag -mdd xml:BAG | grep GEOGCRS
<gco:CharacterString>GEOGCRS["WGS 84",ENSEMBLE["World Geodetic
System 1984 ensemble",MEMBER["World Geodetic System 1984
(Transit)"],MEMBER["World Geodetic System 1984 (G730)"],MEMBER["World Geodetic
System 1984 (G873)"],MEMBER["World Geodetic System 1984 (G1150)"],MEMBER["World
Geodetic System 1984 (G1674)"],MEMBER["World Geodetic System 1984
(G1762)"],MEMBER["World Geodetic System 1984 (G2139)"],ELLIPSOID["WGS
84",6378137,298.257223563,LENGTHUNIT["metre",1]],ENSEMBLEACCURACY[2.0]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],CS[ellipsoidal,3],AXIS["geodetic
latitude
(Lat)",north,ORDER[1],ANGLEUNIT["degree",0.0174532925199433]],AXIS["geodetic
longitude
(Lon)",east,ORDER[2],ANGLEUNIT["degree",0.0174532925199433]],AXIS["ellipsoidal
height (h)",up,ORDER[3],LENGTHUNIT["metre",1]], [... snip ....]
,ID["EPSG",4979]]</gco:CharacterString>
(I see that gdalinfo also issues a "ERROR 1: PROJ: proj_create_compound_crs:
components of the compound CRS do not belong to one of the allowed combinations
of http://docs.opengeospatial.org/as/18-005r4/18-005r4.html#34"; when reading
this, which I suspect comes from the fact that it tries to create a CompoundCRS
from this 3D GeogCRS and the "VERT_CS["unknown", VERT_DATUM["unknown", 2000]]",
so writing 3D GeogCRS isn't really appropriate for BAG)
Even
Le 22/04/2022 à 18:01, Vautour, André (INT) a écrit :
Hi all,
It has just come to my attention that the BAG driver in GDAL is writing the CRS
with a WKT codeSpace and a WKT 2.0 string as the code. While I am fairly sure
we started that incorrect practice here at CARIS with a WKT 1.0 string, this is
the first time I’ve seen a WKT 2.0 string written in there, and I am therefore
concerned about interoperability.
I think we can all agree that what makes the most sense is to write an EPSG
codebase with the EPSG code if we have it, and I think falling back to a WKT
1.0 string if it is not EPSG is a reasonable fallback if it is not EPSG, given
how it has been used in the past, but I am worried that older software won’t
recognize the WKT 2.0 string.
Would you be willing to take a pull request that does that? Worst-case, would
you be fine with changing that WKT 2.0 string to a WKT 1.0 string?
Regards,
André
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