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Hi all,

I am using Delphi 2006 and mappoint 2006 Europe. there is a customer table with longtitude latitude, my program will show the customer's pushpin on the map. all the customers are in UK, but sometimes, the customer's longtitude latitude was wrong, and the pushpin will show in the other country. it's wrong. Does any one know how to verify if the customer's longtitude/latitude is in the UK area?

Thanks in advance

David

You could look on a map and come up with a simple box, and then check against that.

West it is going to be something like -10deg; and about 3 deg east (don't take these for granted!)
I don't know if you need Northern Ireland; but watch out for Ardnamurchan and the Hebrides.
The Ardnamurchan peninsular in Scotland is further west than Land's End. (shhh! don't tell the Lands End tourists!)

London is ~51deg N, so about 50deg for the southern boundary.
If you don't need the Orkneys and Shetlands, then 60N is just off the coast of Scotland (I know that one because I remember everyone being impressed by '60N' when I was in Alaska, but I didn't think much of it as I'd been that far north before...)

Richard

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Thanks Richard,


I wrote a function to check the longitude and latitude as below:

function CheckLongLat(Latitude, Longtitude: Double):boolean;
begin
Result := False;
if (Latitude< ?) or (Latitude >?) then
begin
Result := False;
exit;
end;
if (Longtitude < ?) or (Longtitude >?) then
begin
Result := False;
exit;
end;
Result := True;
end;

I don't know the values of the ?, not sure if it's ok for check the longitude/latitude in the UK area.

All it is, is looking the values up on a map or a website (eg. CIA World Factbook; or the Ordnance Survey's own interactive maps).

I actually live in Texas but I do have some national geological maps of the UK.
From these, the northern tip of the Shetlands is about 60.8N
For the south, the Scily Isles are just below 50N, so 49.8N would give a margin.

For the west, the map goes as far west as 7.3W but that does not include all of Northern Ireland. 8W includes all of the Outer Hebrides - this probably gives enough margin for the far west of Northern Ireland. (the map is drawn to the National Grid which is based on a Transverse Mercator System - grid north and true north differ quite a bit in the far NW).

For completeness, Rockall is close to 13.5W and 57.5N; and St Kilda is at 8.5W and 57.8N.

The Eastern margin is within 2E.

Richard

__________________
Winwaed Software Technology LLC
http://www.winwaed.com
See http://www.mapping-tools.com for MapPoint Tools
See the Geoweb Guru for online mapping

Hi,

You can check first if given coordinates are within the country to make a polygon that encasulated more or less roughly. You can check this artikle, written in Delphi to determine what you try to do: Determing Whether A Point Is Located Inside Polygon - MapPoint Articles - MP2K Magazine

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