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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (SIS-427) Improve CRS.suggestCommonTarget(…) by allowing to know Set<FunctionProperty>
Date Sat, 28 Jul 2018 10:12:00 GMT

     [ https://issues.apache.org/jira/browse/SIS-427?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Martin Desruisseaux updated SIS-427:
------------------------------------
    Description: 
The Mollweide projection added by SIS-426 is not _surjective_: not all (_x_, _y_) values can
be mapped to a (_latitude_, _longitude_) values. Consequently current implementation of {{CRS.suggestCommonTarget(…)}},
which is to suggest converting projected coordinates to geographic coordinates, may not work
for Mollweide. For that projection, it may be more reliable to convert geographic coordinates
to projected coordinates.

For allowing {{CRS.suggestCommonTarget(…)}} to make a better choice, we need to know more
about the {{MathTransform}} properties. One approach would be to add a {{MathTransform.getFunctionProperties()}}
method which would return an {{Set<FunctionProperty>}}. This set can tell us if the
function is invertible, injective, surjective or bijective.


  was:
The Mollweide projection added by SIS-426 is not _surjective_: not all (_x_, _y_) values can
be mapped to a (_latitude_, _longitude_) values. Consequently current implementation of {{CRS.suggestCommonTarget(…)}},
which is to suggest converting projected coordinates to geographic coordinates, may not work
for Mollweide. For that projection, it may be more reliable to convert geographic coordinates
to projected coordinates.

For allowing {{CRS.suggestCommonTarget(…)}} to make a better choice, we need to know more
about the {{MathTransform}} properties. One approach would be to add a {{getFunctionProperties()}}
method which would return an {{Set<FunctionProperty>}}. This set can tell us if the
function is invertible, injective, surjective or bijective.



> Improve CRS.suggestCommonTarget(…) by allowing to know Set<FunctionProperty>
> ----------------------------------------------------------------------------
>
>                 Key: SIS-427
>                 URL: https://issues.apache.org/jira/browse/SIS-427
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>          Components: Referencing
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>            Priority: Major
>
> The Mollweide projection added by SIS-426 is not _surjective_: not all (_x_, _y_) values
can be mapped to a (_latitude_, _longitude_) values. Consequently current implementation of
{{CRS.suggestCommonTarget(…)}}, which is to suggest converting projected coordinates to
geographic coordinates, may not work for Mollweide. For that projection, it may be more reliable
to convert geographic coordinates to projected coordinates.
> For allowing {{CRS.suggestCommonTarget(…)}} to make a better choice, we need to know
more about the {{MathTransform}} properties. One approach would be to add a {{MathTransform.getFunctionProperties()}}
method which would return an {{Set<FunctionProperty>}}. This set can tell us if the
function is invertible, injective, surjective or bijective.



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