(click anywhere on an info box to hide it)
Using Grab a Grid Reference - dual map version
The maps below provide Ordnance Survey (OS) grid references and a range of site boundaries for use with surveying and recording wildlife in the Somerset. The maps are based on the Grab a Grid Reference site by Keith Balmer at
Bedfordshire Natural History Society and adapted for use in Somerset by SERC (see Acknowledgements, below).
On devices with GPS and newer browsers - e.g. smartphones - you may be able to use the device's built-in geolocation. Check out the
using geolocation button below for more details. Otherwise you can proceed without using the geolocation facility.
Drag the
red marker on the left-hand map to where you want a grid reference (
see below for more about grid refs). The
blue marker on the right-hand map tracks the red marker and cannot be dragged. It also tracks the zoom level - but note that the Google map on the left will zoom in closer than the OS maps. The grid references will appear in the grey box below and the corresponding size and colour of grid square is drawn on both maps.
Tick your choice(s) of grid reference from the grey box. Click the "About grid references" button for more information. Note that the grey box also has a full digital Easting/Northing option, plus a Lat/Long option, for checking e.g. against GPS readings.
Clicking on
"Get the marker" will bring it to the centre of the map. If you pan away from the marker, click
"Go to marker" to get back to it.
Additional
boundary layers can be ticked on and off. These only show on the left map. Note that the more detailed layers may load slowly and take a while to appear, especially on older systems or slower internet connections.
The right-hand map shows Ordnance Survey maps of different scales according to the zoom level. This includes the nice OS Landranger maps familiar to walkers and tourists. Ordnance Survey limits the number of map tiles that may be accessed per day, so their map will stop working if this is reached.
The right-hand map copies the position of the left-hand map whenever it is zoomed, panned or the marker moves, but the right map can be can be zoomed and panned on its own. If you've found the place you wanted using the right map, you can move the left map to it using the "Match Left Map to Right Map" button. The "Get The Marker" button moves the marker to the centre of the
left map, so you may want to match the maps first.
The right-hand map also has a
coordinates tracker in the bottom left corner. You can use this to get a quick idea of your changing OS grid reference, by substituting the main letter prefixes for the first number of each coordinate - for example, Easting:2xxxxx,Northing:4xxxxx lies within the SC 100km square, so a reading of E:228600, N:470000 is equivalent to SC286700. Likewise NX=2-5-
The
Search for: box can be used to search for locations, either by a Grid reference (e.g. SC340959), postcode (e.g. IM5 1AU), or a placename - but note that it currently goes to the first matched placename rather than a choice, so you might prefer to use postcodes where available.
Troubleshooting
As with most online maps, you will need to have
Javascript enabled to get the benefit of this page. Without it the maps will be blank, the info boxes won't hide on clicking and the tools won't work. It won't normally be a problem, as most browsers have Javascript enabled by default. If not, you should be able to enable it in the Settings menu of your browser.
Grab a Grid Ref has been tested on a range of browsers and found to work on all except earlier versions of Internet Explorer (v9 and earlier). Earlier versions are functional but the site layout may be a bit sketchy-looking. Mobile browsers will work but may look a little cramped on a small screen.
(click to hide)