| 26 | | If you are using the British Grid system things are more complicated and this |
| 27 | | support is incomplete. If you set the configuration variable force_wgs84 |
| 28 | | to 1, maps will display, but points will be offset from where they should |
| 29 | | be, normally by about 50 metres. This is because the British Grid uses a |
| 30 | | different ellipsoid from Google Maps. We plan to integrate conversion |
| 31 | | routines to fix this in a future release. In the meantime, if you |
| 32 | | advertise the maps you must make users aware of this flaw and tell them |
| 33 | | not to try and "correct" location data! |
| | 26 | If you are using the British Grid system things are more complicated. |
| | 27 | To display accurate maps, you need to have the optional perl module |
| | 28 | Geo::HelmertTransform installed (libgeo-helmerttransform-perl in Debian). |
| | 29 | If this isn't possible, you can still get Google Maps to display by setting |
| | 30 | the configuration variable force_wgs84 to 1, but points will be offset from |
| | 31 | where they should be, normally by about 50 metres. This is because the |
| | 32 | British Grid uses a different ellipsoid from Google Maps. This is not |
| | 33 | recommended; if you do so, you must make users aware of the flaw and tell |
| | 34 | them not to try and "correct" location data! |
