[gdal-dev] Axis order in the kml driver
cedric.traizet at c-s.fr
Wed Jun 5 05:56:30 PDT 2019
I am trying to use the kml ogr driver in gdal 3.0, but there is
something I find weird with the spatial references:
- When a layer is created (in the constructor), a wgs84 geoCRS is
created, without setting its "Axis mapping strategy" to
OAMS_TRADITIONAL_GIS_ORDER, meaning that it uses latitude first and
longitude second. This spatial reference is then compared to the source
spatial reference, and if it doesn't match, a
OGRCoordinateTransformation is created to convert from the source SRS to
wgs84 (as kml only supports wgs84).
- When opening a kml datasource using the driver, a wgs84 geoCRS is
created, this time with its axis mapping strategy set to
OAMS_TRADITIONAL_GIS_ORDER (longitude first and latitude second). A
layer is then created with this spatial reference and compared with a
lat/long wgs84 as described above. And as they mismatch, a coordinate
transformation is created between the two geoCRS.
I think the wgs84 spatial reference of the layer should also have its
axis set to OAMS_TRADITIONAL_GIS_ORDER.
Or maybe I am not understanding correctly of spatial references work in
this driver ? I am still a bit confused with these axis order issues.
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