Martin Desruisseaux created SIS-572:
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Summary: Assign GeoTIFF projection 15 to Polar Stereographic
variant B instead of A
Key: SIS-572
URL: https://issues.apache.org/jira/browse/SIS-572
Project: Spatial Information Systems
Issue Type: Task
Components: Referencing
Affects Versions: 1.3., 1.2, 1.1, 1.0, 0.8, 0.7, 0.6
Reporter: Martin Desruisseaux
Assignee: Martin Desruisseaux
Fix For: 1.4
The GeoTIFF projection #15 ({{CT_PolarStereographic}}) is currently mapped to
operation method EPSG::9810 (_Polar Stereographic *variant A*_) because this is
what the
[geotiff.maptools.org|http://geotiff.maptools.org/proj_list/polar_stereographic.html]
does. But it seems to be an error. It should be mapped to EPSG::9829 (_Polar
Stereographic *variant B*_) instead.
This change is based on the observation that existing GeoTIFF files use the
_Latitude of natural origin_ (GeoTIFF::3081) parameter with values such as
70°N, which is illegal for projection variant A. They probably mean _Latitude
of standard parallel_ (GeoTIFF::3078) instead, which is a parameter of variant
B. This problem is described in more details in [GeoTIFF GitHub issue
#110|https://github.com/opengeospatial/geotiff/issues/110].
We may need to add a hack for remapping the _Latitude of natural origin_
parameter to _Latitude of standard parallel_ when the Polar Stereographic
projection is used in a GeoTIFF file, in order to accept legacy (erroneous)
data.
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