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Database: tune accuracy of Canadian NTv1 file w.r.t NTv2 #1812

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merged 1 commit into from Dec 26, 2019

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rouault commented Dec 25, 2019

As on import of EPSG, we remove the supersession of Canadian NTv1 file w.r.t NTv2
(because the default behaviour of PROJ is to ignore superseded operations). However
the NTv1 operation is advertized with an accuracy of 1m, whereas NTv2 is advertized
with 1.5m. Consequently on areas where both files are valid, and if both files are
available, NTv1 would be selected. So as a workaround, worsen the NTv1 accuracy to
2m so that NTv2 is used in priority.

As on import of EPSG, we remove the supersession of Canadian NTv1 file w.r.t NTv2
(because the default behaviour of PROJ is to ignore superseded operations). However
the NTv1 operation is advertized with an accuracy of 1m, whereas NTv2 is advertized
with 1.5m. Consequently on areas where both files are valid, and if both files are
available, NTv1 would be selected. So as a workaround, worsen the NTv1 accuracy to
2m so that NTv2 is used in priority.
@rouault rouault added this to the 6.3.0 milestone Dec 25, 2019
@rouault rouault merged commit 6c0b5d9 into OSGeo:master Dec 26, 2019
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