NOTE: as of version 0.67, OpenGuides has switched from the Google Maps API to the open source Leaflet mapping library. Our Google Maps support is out of date and no longer maintained. To ensure you're using the latest mapping code, set use_leaflet = 1 in your wiki.conf. The instructions below are retained for the benefit of legacy users. ---------------------------------------------------------------------- As of 0.52, OpenGuides supports Google Maps using the API. The support has a few rough edges that still need ironing out, mostly relating to ellipsoids, and for that reason they aren't exposed by default. To use Google Maps, you need to get an API key from http://www.google.com/apis/maps/signup.html. When you've put this value into the config file as gmaps_api_key, the maps become available to you in two places. Firstly, if you've set "show_gmap_in_node_display", and if the user has set their preferences to display Google Maps, any node which has location information will get an inset map pinpointing the location. Secondly, the URL http://.../wiki.cgi?action=index;format=map becomes a large map with a list of all nodes (regardless of the user settings). The latter will become very slow on any sizable guide (there is work being done on speeding up indexes in general - please see the mailing list). If you don't get maps displayed when you know that the node has location information, read on. Ellipsoids and map accuracy --------------------------- If you are based in the US and inputting points using latitude/longitude, the values in your database will almost certainly correspond to points on Google Maps. If so, simply change the "ellipsoid" configuration variable to "WGS-84" if it's not already set to this, and your maps will display. If you are using the British Grid system things are more complicated. To display accurate maps, you need to have the optional perl module Geo::HelmertTransform installed (libgeo-helmerttransform-perl in Debian). If this isn't possible, you can still get Google Maps to display by setting the configuration variable force_wgs84 to 1, but points will be offset from where they should be, normally by about 50 metres. This is because the British Grid uses a different ellipsoid from Google Maps. This is not recommended; if you do so, you must make users aware of the flaw and tell them not to try and "correct" location data! You may be unlucky enough to be using the UTM input modes (ie not British or Irish National Grid) but have data entered in a mixture of formats. This is likely if your users are from the UK, as you may find a mixture of WGS-84 and Airy (ie British Grid style) based nodes. In this case, you *do* need to correct any that are offset. Only do this if your users input Lat/long values rather than grid Eastings/Northings.