Using Google Maps to Solve an Historical Problem
August 30, 2011 Leave a comment
We have been working closely with Cassini Publishing now for several years and created their award-winning MapMaker historical map browser product and also their automated map production system. So, we were the natural choice to help them with their new Ancestry Maps website.
Ancestry Maps, which is a joint venture between Cassini Publishing and Ancestry.co.uk, is a new take on the successful MapMaker product. Historical maps dating from 1805 to the present day are available for England, Scotland and Wales at a variety of scales and detail. You can enter a place name or postcode, view a large sample map centred on your requested location and then purchase and download the final high quality map.
Although the historical map is correctly centred on the chosen place name or postcode, users wanted the ability to be more precise about how the map is positioned by being able to centre the map on a specific street, building or landmark.
This is especially important when dealing with the more detailed large scale historical maps such as the Ordnance Survey 1:10560 and 1:2500 scale maps. At these scales, individual streets and buildings are clearly visible and easily identifiable and so it becomes more obvious when your map isn’t positioned exactly where you want it.
Users also wanted to be able to position the maps in relation to current day features that often don’t exist on the historical maps, as the landscape of the UK has changed so much over the last 206 years.
The solution was to let the user select a new centre point for the historical map by choosing a point on a current day map.
In order to use the Google Maps API v3 to show the current day map, the centre point of the historical map is converted from UK National Grid coordinates to latitude and longitude. The Google map is then opened in a modal dialog so that the user does not need to navigate away from the historical map sample page.
The user can use any of the Google map layers, including Street View, to zoom and pan and centre their map precisely where they want it. Once they are happy with the positioning, the new Google map centre point is converted from latitude and longitude to UK National Grid coordinates and a new historical map sample is automatically generated.
A neat, simple solution to what was potentially a complex problem!