Sunday 11 August 2013

Comparing layers

About three years ago I created a simple map using OpenLayers to display a base layer and overlay some layers on it. It features layers useful to some GB mappers. From the logs I can see that it is used quite a lot.  All of the slippy maps I've created recently have used Leaflet rather than OpenLayers so I thought I should update my comparison map in Leaflet. You can see the result here.

It has base layers of MapQuest open, the Standard OSM layer or MapQuest roads. For overlays you can choose from the ITO World tiles of OS OpenData Locator anomalies, the OS OpenData StreetView or my tiles showing the Office of National Statistics postcode centroids. Whichever of the overlays are shown you can move the slider (top-left) to change the opacity to make the base or overlay readable.

The browser address line shows the constantly-updated location and zoom, in the new style of the OSM landing page. This makes bookmarking the position easy. There is also a lat / lon display bottom right which shows you the location the mouse is currently pointing at.

I intend to leave the existing oscompare unchanged and maintain this new leaflet-based one in the future. If anyone would like any other layers or if there is any problem please comment.

Thanks to MapQuest and ITO World for their map tiles and their processes for updating them, thanks to Ordnance Survey for their OpenData and thanks to the OSM admins who manage the OS StreetView tiles.

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