geography

How do you calculate the distance between 2 cities? Dana the Sane If you need to take the curvature of the earth into account, the Great-Circle distance is what you're looking for. The Wikipedia article probably does a better job of explaining how the formula works than me, and there's also this aviation formulary page that covers that goes into more detail. The formulas are only the first part of the puzzle though, if you need to make this work for arbitrary cities, you'll need a location database to get the lat/long from. Luckily you can get this for free from Geonames.org , although there

I am using geography.STDistance() to return the distance between two single point locations. I'm curious as to which measurement is used for the return value? Is it in KM's, miles or perhaps some other? I'm getting results back upwards of 250k but i've no idea if im doing something wrong with my TSQL as these are historical locations(i.e. they no longer exist) so I can't just do a quick lookup. declare @p1 geography declare @p2 geography SELECT @p1 = Location from tblLocations where Id = 1 SELECT @p2 = Location from tblLocations where Id = 2 select @p1.STDistance(@p2) I think the return

I have a geography field stored in my database, holding a linestring path. I want to move a point n meters along this linestring, and return the destination. For example, I want the destination point 500 meters along the linestring starting from its beginning. Here's an example -- what is the YourFunctionHere ? Or, is there another way? DECLARE @g geography; SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656, -122.310 47.690)', 4326); SELECT @g.YourFunctionHere(100).ToString(); Daniel Vassallo This is a little bit tricky, but it is certainly possible. Let's start

Hello, i have the following code in SQL Server, why if i want to calculate the sTArea of @geog fails and with @geom succeed?, how can i convert this polygon from geometry to geography datatype in order to get the STArea?, thank you. DECLARE @geom geometry; SET @geom = geometry::STGeomFromText('POLYGON ((-99.213546752929688 19.448402404785156, -99.2157974243164 19.449802398681641, -99.2127456665039 19.450002670288086, -99.213546752929688 19.448402404785156))', 4326); select @geom.STArea(); DECLARE @geog geography; SET @geog = geography::STGeomFromText('POLYGON ((-99.213546752929688 19

I'm creating a Google map mashup and am using SQL 2008. I will have a large number of points on the earth and will want to perform various calculations on them in SQL - such as selecting all points contained within a particular polygone, or select all points within 10km of XY. I have never used and SQL spatial features before. Should I use the geography or the geometry datatype for this? Geography is the type that is intended for plotting points on the earth. If you have a table that stores Google Maps points like this: CREATE TABLE geo_locations ( location_id uniqueidentifier NOT NULL,

I am trying to use Nhibernate with the Sql 2008 Geography type and am having difficulty. I am using Fluent Nhibernate to configure which I am fairly new to so that may be the problem as well. First, the class I am trying to persist looks something like: public class LocationLog : FluentNHibernate.Data.Entity { public virtual new int Id {get;set;} public virtual DateTime TimeStamp {get;set;} public virtual GisSharpBlog.NetTopologySuite.Geometries.Point Location {get;set;} } The mapping class looks like: public class LocationLogMap : ClassMap<LocationLog> { ImportType<GisSharpBlog

I've written some code that includes a nested loop where the inner loop is executed about 1.5 million times. I have a function in this loop that I'm trying to optimize. I've done some work, and got some results, but I need a little input to check if what I'm doing is sensible. Some background: I have two collections of geographic points (latitude, longitude), one relatively small collection and one relatively huge collection. For every point in the small collection, I need to find the closest point in the large collection. The obvious way to do this would be to use the haversine formula. The