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Posted to commits@sis.apache.org by "Martin Desruisseaux (JIRA)" <ji...@apache.org> on 2019/03/08 18:29:00 UTC

[jira] [Updated] (SIS-445) NetCDF store should be robust to localization grid crossing anti-meridian

     [ https://issues.apache.org/jira/browse/SIS-445?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Martin Desruisseaux updated SIS-445:
------------------------------------
    Issue Type: Improvement  (was: Task)

> NetCDF store should be robust to localization grid crossing anti-meridian
> -------------------------------------------------------------------------
>
>                 Key: SIS-445
>                 URL: https://issues.apache.org/jira/browse/SIS-445
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>          Components: Referencing, Storage
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>            Priority: Major
>             Fix For: 1.0
>
>
> NetCDF files often have a "longitude" and "latitude" variables (names may vary) containing longitude and latitude values of every pixels. For raster data in Pacific ocean, the range of longitude sometime cross the anti-meridian, where longitude values suddenly drop from +180° to -180°. This discontinuity breaks our attempt to compute an affine transform approximation in {{LocalizationGridBuilder}}, produces wrong results when interpolating values in this area of the grid, and makes more difficult to converge when performing an inverse transformation.
> The proposed fix is to detect when such discontinuity happens, and add or subtract 360° on one side in order to get continuous values. Inconvenient is that some values become outside the [-180 … 180] range. In some case it can be outside the [0 … 360] range too (i.e. the data may turn around the Earth more than one lap).



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