[SIS-486] Some map projections produce wrong results when |Δλ| > 180°

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8, 1.0
• Fix Version/s: 1.1
• Component/s: Referencing
• Assignee: Martin Desruisseaux
• Reporter: Martin Desruisseaux
• Created: 21/Dec/19 13:40
• Updated: 20/Aug/22 09:50
• Resolved: 21/Dec/19 16:11

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°).

Issue Links

• breaks: SIS-224 Oblique and Equatorial Stereographic (EPSG:9809)
• breaks: SIS-232 Albers Equal Area (EPSG:9822)
• breaks: SIS-239 Lambert Conic Conformal 2SP (EPSG:9802)
• breaks: SIS-240 Lambert Conic Conformal 1SP (EPSG:9801)
• breaks: SIS-452 Satellite-tracking projections
• breaks: SIS-241 Lambert Conic Conformal West Orientated (EPSG:9826)
• relates to: SIS-547 Mercator projection should wraparound longitude values