
Type: Task

Status: Resolved

Priority: Major

Resolution: Fixed

Affects Version/s: 0.8, 1.0

Fix Version/s: 1.1

Component/s: Referencing

Labels:None
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)
 SatelliteTracking projection
This problem impacts in particular the cases when one of above projections is used in an area crossing the antimeridian (±180°).
 breaks

SIS452 Satellitetracking projections
 Resolved

SIS224 Oblique and Equatorial Stereographic (EPSG:9809)
 Closed

SIS232 Albers Equal Area (EPSG:9822)
 Closed

SIS239 Lambert Conic Conformal 2SP (EPSG:9802)
 Closed

SIS240 Lambert Conic Conformal 1SP (EPSG:9801)
 Closed

SIS241 Lambert Conic Conformal West Orientated (EPSG:9826)
 Closed