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https://issues.apache.org/jira/browse/SIS-486?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Martin Desruisseaux updated SIS-486:
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Description:
Some map projections produce a wrong result when the difference Δλ between the
longitude value and the central meridian is greater than 180°. For most map
projections there is no problem because the Δλ value is used directly in
trigonometric functions which perform automatically the range reduction for us.
For example sin(200°) = sin(-160°). However there is a few map projections
where the longitude value is transformed (e.g. multiplied by some factor)
_before_ to be given to a trigonometric function. For such map projections, we
must apply the range reduction ourselves.
Impacted map projection methods in Apache SIS 1.0 are:
* Albers Equal Area (EPSG::9822)
* Lambert Conic Conformal (EPSG::9801, 9802, 9826)
* Oblique Stereographic (EPSG::9809)
* Satellite-Tracking projection
was:
Some map projections produce a wrong result when the difference Δλ between the
longitude value and the central meridian is greater than 180°. For most map
projections there is no problem because the Δλ value is used directly in
trigonometric functions which perform automatically the range reduction for us.
For example sin(200°) = sin(-160°). However there is a few map projections
where the longitude value is transformed (e.g. multiplied by some factor)
_before_ to be given to a trigonometric function. For such map projections, we
must apply the range reduction ourselves.
Impacted map projection methods in Apache SIS 1.0 are:
* Albers Equal Area (EPSG::9822)
* Lambert Conic Conformal (EPSG::9801, 9802, 9826,)
* Oblique Stereographic (EPSG::9809)
* Satellite-Tracking projection
> Some map projections produce wrong results when |Δλ| > 180°
> -----------------------------------------------------------
>
> Key: SIS-486
> URL: https://issues.apache.org/jira/browse/SIS-486
> Project: Spatial Information Systems
> Issue Type: Task
> Components: Referencing
> Affects Versions: 0.8, 1.0
> Reporter: Martin Desruisseaux
> Assignee: Martin Desruisseaux
> Priority: Major
> Fix For: 1.1
>
>
> Some map projections produce a wrong result when the difference Δλ between
> the longitude value and the central meridian is greater than 180°. For most
> map projections there is no problem because the Δλ value is used directly in
> trigonometric functions which perform automatically the range reduction for
> us. For example sin(200°) = sin(-160°). However there is a few map
> projections where the longitude value is transformed (e.g. multiplied by some
> factor) _before_ to be given to a trigonometric function. For such map
> projections, we must apply the range reduction ourselves.
> Impacted map projection methods in Apache SIS 1.0 are:
> * Albers Equal Area (EPSG::9822)
> * Lambert Conic Conformal (EPSG::9801, 9802, 9826)
> * Oblique Stereographic (EPSG::9809)
> * Satellite-Tracking projection
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