Opened 16 years ago

Closed 15 years ago

#77 closed defect (fixed)

Coordinates are off when viewed from Google

Reported by: Ivor Williams Owned by: Earle Martin
Priority: normal Milestone:
Component: london.openguides.org Version: svn
Severity: normal Keywords: geodata
Cc:

Description

Google Maps has highlighted that the Lat/Long? coordinates are offset from the maps.

see The Millenium Dome, for an example: http://www.nurflax.net/cgi-bin/openguides/wiki.cgi?action=index;format=map&long=0.006849&lat=51.503005&zoom=1

Change History (5)

comment:1 Changed 16 years ago by bob

isnt this just an effect of the fact that the page has the wrong coords anyway.

comment:2 Changed 16 years ago by ChristopherSchmidt

London for a long time used a manual converter from OS X/Y coords to GpS Lat/Lon?. This converter used Airy projection. Google Maps uses WGS-84 projection. Although one may be more accurate on the actual planet or somethign (I don't know) many of London's points will not map properly onto Google Maps because of this.

comment:3 Changed 16 years ago by anonymous

As will be included in documentation when the google maps stuff is properly released, there are fudge factors involved at present. I'll include conversion code so that non-wgs84 stored data can be used with google maps.

That said, guides getting lat/long data (rather than os coords) directly from users need to check their data for consistency anyway, and also define what their stored data will be in the edit form.

comment:4 Changed 16 years ago by Dominic Hargreaves

(that last was me, sorry)

comment:5 Changed 15 years ago by nick

Resolution: fixed
Status: newclosed

This should now be fixed, if you have the latest OpenGuides, Geo::HelmertTransform? installed, and you have the following options set:

geo_handler = 1 force_wgs84 = 0

(Any data where you entered a lat/long, and it was badly converted to easting+northing, will still be wrong. However, any entered as a correct easting+northing will work)

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