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  1. Spatial Information Systems
  2. SIS-486

Some map projections produce wrong results when |Δλ| > 180°

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    Details

    • Type: Task
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.8, 1.0
    • Fix Version/s: 1.1
    • Component/s: Referencing
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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

      This problem impacts in particular the cases when one of above projections is used in an area crossing the anti-meridian (±180°).

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              • Assignee:
                desruisseaux Martin Desruisseaux
                Reporter:
                desruisseaux Martin Desruisseaux
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                • Created:
                  Updated:
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