Bug report #5329
wrong ellipsoid semi-minor axis calculation inside QgsDistanceArea
| Status: | Closed | ||
|---|---|---|---|
| Priority: | High | ||
| Assignee: | - | ||
| Category: | - | ||
| Affected QGIS version: | master | Regression?: | No |
| Operating System: | Easy fix?: | No | |
| Pull Request or Patch supplied: | No | Resolution: | fixed |
| Crashes QGIS or corrupts data: | No | Copied to github as #: | 15030 |
Description
In Qgis the semi-minor axis of the ellipsoid is calculated [1] with:
b = a - (f/a)
where
b = semi-minor axis
a = semi-majot axis
f = inverse flattening
while it should be:
b = a - (a/f)
In Qgis the WGS84 semi-minor axis is 6378136,xxx
while it should be 6356752.xxx
This causes wrong distance calculations on ellipsoid as reported here:
http://lists.osgeo.org/pipermail/qgis-user/2012-April/016535.html
I've done a pull request into master repo: https://github.com/qgis/Quantum-GIS/pull/115
giovanni
[1]
http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsdistancearea.cpp#L153
qgisdistancearea.diff 
- patch
(720 Bytes)
History
#1
Updated by Nathan Woodrow over 12 years ago
- Resolution set to fixed
- Status changed from Open to Closed
Fixed in 55d92681d7eef2
Thanks