Hi,

you are right, it can't be done at present.  You are not the first to request this, so it is high on the list of enhancements.  Having already discussed this, we are likely to make it pretty flexible so you can zoom to any part of the country.  We will be doing a formal round of requirements gathering and web service improvements during the summer - this will definately be one of them.

Jon

Yes, that's exactly how we would do it.

Jon

That's great Nicole - thanks very much. I may not get chance to try it out for a day or two but I'll let you know how I get on.

Cheers

Alan

Hi

I was on the verge of trying out this bounding box, and was just grappling with my inability to understand the coordinate systems on offer when I noticed the statement "its maximum area is restricted to 900 km2"

Now, it is a well known fact that this is 0.043 times the size of Wales (see www.sizeofwales.co.uk) so I fear that it is going to serve neither Alan's purpose nor mine.

It is nearly the size of quarter of a million football pitches though so it may be useful. Can anyone explain for me and others how to go from either
- an Ordnance Survey grid reference, like SU6168789671 or
- latitude and longitude like 51.60251747585253N, 1.110716164112091W,
(both of which define the location of my current sitting position in a manner I am familiar and comfortable with,)
to the x,y coordinates of a bounding box as I am not finding the documentation sufficient.

Thanks,
Jim Bacon.

Thanks, Nicole. I now have myself some maps of Wales which is great. Thing is, by using Lat and Long I am ending up with squares which are cut by the bounding box so I would like to use the Ordnance Survey grid to make sure my bounding box falls on 10km boundaries.

How can I turn a grid reference like SU68 (the 10km square I am in) in to a bounding box coordinate?

Jim

Thanks, Nicole.

I now have a map of Wales that I am happy with (see example).

For the benefit of others, there is an all numeric way of representing a location using the Ordnance Survey grid. One way of looking at it is as eastings and northings, in metres, from an origin near the Scilly Isles.

To obtain such coordinates from a normal 6-figure grid reference, e.g. SU616896, first expand it to a 10-figure reference, SU6160089600. The eastings part of this is 61600 and the northings part is 89600. Now SU defines a 100km square which can equally be described by an easting and a northing from an origin. In the map below, the origin is in the bottom left, so that square SV is described as (0,0), square SU as (4, 1), square HP as (4, 12) and so on. These values then prefix the eastings and northings we already have so, ultimately, SU616896 converts to (461600, 189600). In bounding box terms, eastings is the x-coordinate and northings the y-coordinate.

[img]http://upload.wikimedia.org/wikipedia/commons/e/e3/National_Grid_for_Great_Britain_with_central_meridian.png[/img]

The rather untidy looking website Nicole points us to will do this conversion for you. The other vital piece of information is that this form of coordinates is EPSG_27700.

I hope I've got that all right. It seems to work - although not if you're wanting a map of Ireland, of course.

Jim