Hi everyone, GDAL 3.5.0
I have an application written in c# that takes data in WGS84 and transforms the coordinates to the relevant local projected CRS. In the code I use a URN with the EPSG transformation code, for example for ED50 data - urn:ogc:def:coordinateOperation:EPSG::1311 to convert between EPSG:4326 and EPSG:4230 and it works great for going from EPSG:4230 > EPSG:4326 but it doesn't give the correct results the other way. Checking the coordinates with gdaltransform from the command line using the following - gdaltransform -s_srs EPSG:4326 -t_srs EPSG:4230 -ct urn:ogc:def:coordinateOperation:EPSG::1311 I get this - WGS84 (EPSG:4326) 2.25661712354279 56.4136492649363 ED50 (EPSG:4230) 2.25511244583886 56.4129769077511 which are the same coordinates I get through code, which is not right, but with the -i switch - gdaltransform -s_srs EPSG:4326 -t_srs EPSG:4230 -ct urn:ogc:def:coordinateOperation:EPSG::1311 -i I get this - ED50 (EPSG:4230) 2.25812179682132 56.414321584992 which is correct. In the gdal docs there is a bReverseCT boolean parameter for SetCoordinateOperation that is not accessible and is set to always be false in the SWIG interface. I set the correct Axis mapping on the spatial reference within code. I'm no doubt missing something, what am I doing wrong? thanks very much, -Gordon
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