On Thu, Feb 28, 2013 at 3:18 PM, Serge Fonville <serge.fonville@xxxxxxxxx>wrote: > well, not exactly. > But I can help you (so can others) to go through code flow (it will > probably be tedious) > > you have a position you start and a certain distance from that point (in a > circle) > From thereon you substract start(x,y) from dest(x,y) by substracting x from > x and y from y the diffence is the amount of degrees between the two points > are apart, if you add instead you determine a point. > > so for example you are currently at long: 75, lat: 31 and you want to know > some point 6.9 miles away. > you start by adding 0 to 75 and 0.1 to 31 you then have one point (both are > degrees and one degree is roughly 69 miles) you can also do the opposite, > add 0.1 to 75 and 0 to 31, you can also add 0.05 to both (again totaling > 0.1), mind though the values that total 0.1 are absolute, even though the > long/lat may be negative. > > The point is that the values added are combined the distance you want to > measure against. > From thereon you can determine if there is an address at the location > (using reverse geo-coding). > when increasing the number you add, you measure further and further > you'll have to do that all arround the point you started from > > more information about how long/lat works: > http://www.nationalatlas.gov/articles/mapping/a_latlong.html > > HTH > > Kind regards/met vriendelijke groet, > > Serge Fonville > > http://www.sergefonville.nl > > Convince Microsoft! > They need to add TRUNCATE PARTITION in SQL Server > > https://connect.microsoft.com/SQLServer/feedback/details/417926/truncate-partition-of-partitioned-table > > <snip /> > You should be careful of statements like "one degree is roughly 69 miles." While this is true for latitude, it is only true for longitude at the equator. To get the distance between two sets of latlon coordinates, you need to use the great circle equation: http://www.movable-type.co.uk/scripts/latlong.html -- --Zootboy Sent from some sort of computing device.
