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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SIS-318) Support PassThroughTransform directly into AbstractMathTransform
Date Thu, 29 Nov 2018 10:42:00 GMT

     [ https://issues.apache.org/jira/browse/SIS-318?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Martin Desruisseaux reassigned SIS-318:
---------------------------------------

    Assignee: Martin Desruisseaux

> Support PassThroughTransform directly into AbstractMathTransform
> ----------------------------------------------------------------
>
>                 Key: SIS-318
>                 URL: https://issues.apache.org/jira/browse/SIS-318
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>          Components: Referencing
>    Affects Versions: 0.5, 0.6, 0.7, 0.8
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>            Priority: Minor
>              Labels: performance
>
> Move the {{firstAffectedOrdinate}} and {{numTrailingOrdinates}} fields from {{PassThroughTransform}}
to its {{AbstractMathTransform}} parent class. Every {{AbstractMathTransform}} subclasses
should then take those fields in account. We expect no performance penalty on {{AbstractMathTransform}}
subclasses since it would just change the value in an addition which is applied anyway. On
the other hand, it may provide significant performance gain by reducing the need for the {{PassThroughTransform}},
which can hardly implement the {{transform}} method in an efficient way.
> It would also make easier to concatenate the matrices of linear transforms. In the current
implementation we lost a concatenation opportunity if one linear transform is the last {{MathTransform}}
(in a chain of a concatenated transforms) inside the {{PassThroughTransform}}, while the other
linear transform is the first {{MathTransform}} outside the {{PassThroughTransform}}. We could
move the former linear transform outside the {{PassThroughTransform}}, but it cause confusing
WKT to be formatted if the transforms inside the {{PassThroughTransform}} have a {{ContextualParameters}}.
We expect that this problem would be solved with the fix proposed in this issue.



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